Subunit Of DNA-dependent RNA Polymerase Research Articles

First Report of Botrytis cinerea Causing Stem Rot on Hydrangea macrophylla in China.

Hydrangea (Hydrangea macrophylla), commonly referred to as big leaf hydrangea, is a species within the Hydrangeaceae family notable for its ornamental value. Characterized by its vividly colored sepals and lush, striking inflorescences, this species is globally esteemed as both a potted and landscape plant. Notably, in 2022, an alarming incidence of stem rot was observed in approximately 40% of H. macrophylla plants aged between six and twelve months within 16 greenhouses situated in Nanjing City (N 31°14', E 118°22'), Jiangsu Province, China. Initial symptoms of the disease manifested as wet gray-black spots at the base of the seedlings and stems, progressing to a necrotic gray-white discoloration in the stems and accompanied by the growth of gray mold on the affected parts. This infection ultimately led to the wilting of the leaves and the death of the seedlings. For pathogen identification, stem tissues at the interface of diseased and healthy sections were excised, surface-sterilized with 75 % ethanol for 30 s, followed by a 2 - 3 min treatment with 3% sodium hypochlorite, and subsequently rinsed three times with sterile water before air drying. Sections measuring 2 - 3 mm were then cultured on potato dextrose agar (PDA) medium, supplemented with 50 mg/mL rifampicin (RFP), and incubated at 25 ℃ for 3 - 5 d (Zhou et al. 2022). Upon 2 - 3 days of incubation, notable growth of fungal colonies was observed. Mycelial clusters from the periphery of these colonies were subsequently transferred to fresh PDA plates and incubated at 25 ℃ for an additional 5 - 7 d. A particular colony, designated JSNJ2022-2 and now preserved at the Jiangsu Academy of Agricultural Sciences, was selected for detailed examination. This colony exhibited a flocculent texture, with a coloration ranging from grey-white to light brown. It was characterized by the presence of irregularly formed, hard sclerotia within the hyphae. The conidiophores were observed to be slender and erect, featuring dendritic branches at their extremities. The conidia were clustered on the conidiophore like grapes. These conidia were generally colorless or grey, oval in shape, smooth and transparent, and measured between 6.4 - 12.2 × 7.3 - 18.2 μm (n = 50). For genetic analysis, genomic DNA (gDNA) was extracted using the DNA secure Plant Kit (Tiangen Biotech, Beijing, China). Polymerase chain reaction (PCR) amplification was performed using a set of universal primers of ITS1/ITS4 (White et al. 1990), primers corresponding to the specific sequences of glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) (Yang et al. 2020). The resultant PCR products were sequenced, and the resulting sequences were submitted to the GenBank database, under the accession numbers OP131597, OP142320, OP142321, and OP142322, respectively. BLAST analysis of the sequences obtained from the isolate JSNJ2022-2 revealed a high degree of genetic similarity, ranging from 99 to 100%, with known sequences of Botrytis cinerea (accessions MK051124.1, MH796662.1, MH479931.1, and KU760986.1). To elucidate the phylogenetic position of the isolate, a phylogenetic tree was constructed using the maximum likelihood method, supported by 1,000 bootstrap replications, in the Mega7 software (Kumar et al. 2016). The results of this analysis confirmed that the strains under study clustered within the same branch as B. cinerea. To establish the pathogenicity of the isolate, Koch's postulates (Falkow 1988) were employed. Healthy potted H. macrophylla seedlings, approximately three months old, were wound inoculated at the base of the seedlings with a 6 mm diameter mycelium plug of JSNJ2002-2 cultivated on PDA for 3 days, which was subsequently covered with moistened degreasing cotton. Control plants were treated with moistened degreasing cloths minus the pathogen. Post-inoculation, these plants were placed in a growth chamber maintained at 25 ℃ with a relative humidity range of 60 - 80%. After a 3-d incubation period, the inoculated plants displayed symptoms identical to those initially observed in the greenhouse. The pathogen was successfully re-isolated from these inoculated plants and was morphologically re-confirmed as B. cinerea, thus satisfying the criteria of Koch's postulates. To our knowledge, this report represents the first documented incidence of B. cinerea causing stem rot in H. macrophylla in China.

First Report of Chocolate Spot Caused by Botrytis eucalypti on Faba bean in China.

Faba bean (Vicia faba) is one of the characteristic economic crops in Qinghai Province of China, which has multiple uses as grain, vegetable, fodder, fertilizer and medicine. Chocolate spot is a critical disease of faba bean in the world, and it is widely spread in all production areas of Qinghai. In August 2021, a severe occurrence of chocolate spot was found in a faba bean field in Xunhua County, Qinghai Province (35°52'N, 102°22'E, alt. 1890m). All plants in the field were affected by this disease. A voucher specimen was deposited in the Herbarium of Plant Pathology, College of Agricultural and Forestry Sciences at Qinghai University under accession No. PY015. The pathogen infected the leaves and stems, causing small irregular red spots to appear, which later coalesce into larger spots and faded green lesions appear around the spots. Diseased leaf pieces 5 mm2 were surface sterilized with 75% ethyl alcohol for 30s, 1.2% NaOCl for 30s, and rinsed three times with sterile water. They were then plated on potato dextrose agar (PDA) at 22℃ for 10 days in the dark. Fungal colonies are initially white, then gray, and have produced spores by 5 days. Conidia are clusters, ellipsoidal or ovoid, 9-14 × 6-9 μm. The conidiophore is straight, terminally enlarged, septate, 300-1500 μm long, 8-13 μm wide. No sclerotia were observed during culture. DNA of the strain PY015 was extracted by CTAB method. Molecular identification was first performed using the universal region of ITS (ITS1/ITS4). The PCR product was sequenced, the sequence was deposited in GenBank under the accession number OR739575. The results showed 100% similarity to Botrytis spp. (KX301016, MT250940, LC519322) in BLAST search. Molecular characterization was continued using five specific primer pairs: RPB2 (DNA-dependent RNA polymerase subunit II, RPB2-5F/RPB2-7cR), NEP1 and NEP2 (necrosis and ethylene-inducing proteins, NEP1for/ NEP1revB and NEP2forD/NEP2revD), HSP60 (heat-shock protein 60, HSP60for/HSP60rev), G3PDH (glyceraldehyde-3-phosphate dehydrogenase, G3PDHfor/G3PDHrev). The sequences of PY015 were deposited in GenBank (accession numbers: OR731179, OR731180, OR731181, OR731182, OR731183), and all five sequences showed 100% similarity to Botrytis eucalypti YZU171088 (accession numbers: MH614610 MH614611, MH614612, MH614613 MH614614). A phylogenetic tree based on these five genes was constructed using Mega7.0 (1000 bootstrap replicates, neighbor-joining method), and PY015 was placed in the same clade as YZU171088 with 100% bootstrap values. Morphological and molecular biological results confirmed that isolate PY015 was B. eucalypti. To fulfill Koch's postulates, the spore suspension (2 × 105 conidia/ml) was sprayed on healthy faba bean (Yun-122) plants at the 10-leaf stage, while an equal amount of sterile distilled water was applied to controls. After 7 days, the inoculated plants showed symptoms consistent with field infection and B. eucalypti was re-isolated using the same protocol, while the control remained asymptomatic. The pathogenicity test was repeated twice. The same isolates were recovered from symptomatic leaves and identified by NEP1 sequence. B. eucalypti was morphologically and molecularly identical to the original isolates, completing Koch's postulates. Currently, Botrytis fabae, Botrytis fabiopsis, and Botrytis cinerea are the main pathogens of chocolate spot on faba bean that have been identified and reported nationally and internationally. B. eucalypti is a new species discovered from eucalyptus in southern China in 2016, and its current hosts are only eucalyptus and citrus. To our knowledge, the present study is the first report of chocolate spot caused by B. eucalypti on faba bean in China.

First report of Botrytis cinerea causing gray mold on Alternanthera philoxeroides in China.

Alternanthera philoxeroides is a perennial herbaceous plant used as a forage crop (Wang et al. 2005) and is known to have medicinal properties. One of notable active components is flavonoids, which have been found to exhibit anti-Hepatitis B Virus activity (Li et al. 2016). In 2021, a leaf spot on A. philoxeroides was observed in the science and education experimental park of Hebei Agricultural University (38°49'38″ N, 115°26'39″ E). Initial symptoms included leaf tissue water loss, chloro-sis and elliptical lesions scattered across the leaf margin with further development leading to ellipse-shaped disease spots and leaf wilting (Fig. 1A). In the field, 50 plants of A. philoxeroides were randomly selected to investigate and quantify dis-ease. Incidence of leaf disease was approximately 25%, and the infected leaves ex-hibited an average affected area of about 20%. In order to identify the pathogen, three diseased plants were randomly selected from different areas. Stems and leaves of diseased plants were cut into pieces (2 to 3 mm × 5 mm) and disinfested with 1% sodium hypochlorite for 1 minute. After rinsing with sterile water three times, each lesion sample was isolated and purified on PDA at 25°C. Eventually, all samples pro-duced morphologically consistent colonies of pure strains. From the 9 isolates ob-tained, ZLQ-1 was selected as a representative isolate for further study. Colonies were initially white, turning gray from the centre, then gray-brown with cottony aerial hyphae, and finally growing black, stiff, round or irregular sclerotia (0.6 to 4.0 mm × 1.1 to 4.2 mm, n=50) (Fig1. B, C). ZLQ-1 exhibited branched conidia with en-larged apical cells. The conidia of this isolate were unicellular, ovoid or ellipsoid in shape, with dimensions ranging from 5.8 to 16.9 μm × 6.3 to 11.2 μm (n=50) (Fig. 1D). These morphological characteristics were consistent with Botrytis cinerea (Ellis, 1971). The genes of internal transcribed spacer (ITS), heat shock protein (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) were amplified with specific primers ITS1/ITS4, HSP60-F/HSP60-R, RPB2-F/RPB2-R and G3PDH-F/G3PDH-R (Aktaruzzaman et al., 2022). Sequences were deposited into GenBank with accession numbers ON479490 for ITS, ON572246 for G3PDH, ON572248 for HSP60, ON572247 for RPB2. BLASTn analysis showed that the ITS sequence shared 99.62% similarity to B. cinerea (CP009808), and the sequences of the other three nuclear protein-encoding genes (G3PDH, HSP60, and RPB2) showed at least 99.9% identity with the genome of B. ci-nerea (B05.10) (Staats et al. 2005). We have inoculated 10 healthy A. philoxeroides leaves with a suspension of 1x105 spores/mL, and used sterile water treatment as control (Aktaruzzaman et al., 2022). Each leaf was inoculated with 10 μL spore sus-pension. After 7 days in a controlled incubation environment (25℃, 40%RH), the plants inoculated with conidial suspensions displayed lesions covered in a gray-white mycelial layer, resembling those observed in the field (Fig. 1E-G). In con-trast, the plants inoculated with sterile water remained unaffected. Morphological and PCR analysis confirmed that the pathogen responsible for the observed symp-toms was B. cinerea. Koch's postulates were fulfilled as the same pathogen was con-sistently re-isolated from the inoculated leaves and confirmed to be B. cinerea through morphological and molecular methods. This is the first reported case of B. cinerea causing gray mold on A. philoxeroides in China. It is important to monitor and prevent B. cinerea infection during cultivation to ensure the production of healthy Chinese medicine and feed.

First Report of Botrytis californica Causing Gray Mold on Blueberry in China.

Blueberry (Vaccinium corymbosum) is a perennial shrub which grows in acid soil. Its cultivation area has recently expanded rapidly due to its unique flavor and high nutritional value (Silver and Allen 2012). In June 2021, gray mold symptoms (8 to 12% incidence) were observed on harvested fruits of the blueberry cultivar 'Lanmei 1' during storage in Jiangning (31°50'N, 118°40'E), Nanjing, China. The infection started with wrinkles, atrophy, and depressed spots on the fruit surfaces, ultimately resulting in fruit rot. To determine the causal agent, diseased fruits were sampled and rinsed with sterile water (Gao et al. 2021). Small fragments (5 × 5 × 3 mm) of decayed tissues were excised and plated onto acidified potato dextrose agar (PDA) (containing 4 ml of 25% lactic acid per liter). Plates were incubated at 25°C for 3 to 5 days, and edges of fresh culture were transferred onto new plates. This procedure was repeated thrice to obtain pure cultures. Two isolates (BcB-1 and BcB-2) were obtained. Their colonies appeared whitish to gray, with an average daily growth rate of 11.3 ± 0.6 mm (no. of plates = 30). Conidiophores were long and erect, 2560.9 to 4885.3 μm × 10.7 to 13.0 μm in size. Conidia were one-celled, elliptical to ovoid, nearly hyaline, and 9.6 to 12.5 μm × 6.7 to 8.9 μm in size. Sclerotia were gray to black in color and round or irregular in shape. These morphological features were identical to those of Botrytis spp. (Amiri et al. 2018). To further identify the isolates, we amplified four genetic markers including internal transcribed spacer region (ITS), heat-shock protein 60 (HSP60), glyceraldehyde-3-phosphate dehydrogenase (G3PDH), and DNA-dependent RNA polymerase subunit II (RPBII) (Saito et al. 2014; Walker et al. 2011). Sequences of BcB-1 and BCB-2 were deposited in GenBank under accession nos. OP721062 and OP721063 for ITS, OP737384 and OP737385 for HSP60, OP746062 and OP746063 for G3PDH, and OP746064 and OP746065 for RPBII, respectively. BLAST analysis indicated that these sequences shared high identities (99 to 100%) with those of other B. californica isolates. Phylogenetic analysis showed that BcB-1 and BcB-2 clustered with several reference isolates in the B. californica clade. To confirm their pathogenicity, fresh blueberry fruits were surface sterilized with 0.5% sodium hypochlorite, rinsed with sterile water, air-dried, then wounded thrice per fruit using a sterile needle at the equator. Twenty wounded fruits were sprayed with 10 ml conidial suspension (1 × 105 conidia/ml) of each isolate onto the fruit surface. Twenty fruits treated with sterile water were used as controls. Inoculated or non-inoculated fruits were incubated at 25°C with 90% relative humidity. The pathogenicity test was performed twice. After 5 to 7 days, all inoculated fruits developed disease symptoms similar to those observed on the original fruits, while non-inoculated control fruits were asymptomatic. Re-isolated pathogens from the inoculated fruits exhibited identical morphological characteristics to those of BcB-1 and BcB-2. Their identity as B. californica was also verified based on their ITS sequences. Previously, B. californica has been reported to cause gray mold on blueberry in the Central Valley of California (Saito et al. 2016). To our knowledge, this is the first report of B. californica causing gray mold on post-harvest blueberry fruits in China. These results can provide the basis for future studies on the occurrence, prevention, and control of this disease.

Fusarium pernambucanum Causing Leaf Yellow Spot on Melon (Cucumis melo L.), a New Disease in China.

Melon (Cucumis melo L.) is a member of the Cucurbitaceae family, and is an important economic and horticultural crop. In March 2022, melon plants in greenhouses exhibited severe leaf yellow spot symptoms in Changjiang County (109°13'N, 19°28'E), Hainan Province. The incidence of the disease was about 30-50%. Lesions initially appeared as yellow dots on leaves and expanded irregularly. Gradually, brown spots appeared, and finally the whole leaves turned yellow and resulted in blighting and death of foliage (Figure 1.). A total of four symptomatic plants were sampled from about 0.2 ha of an area. Symptomatic leaves were excised, surface disinfected with 2% (w/v) NaOCl, rinsed three times with sterile distilled water, and placed on potato dextrose agar (PDA) followed by incubation at 25°C in the dark for 5 days. The pure cultures were obtained by the hyphal-tip method. A total of eight fungal isolates with similar colony characteristics were recovered from the four symptomatic plants. Three DNA fragments (ITS, TEF1, and RPB2) of the eight isolates showed 100% sequence identity based on the molecular identification methods described below. Therefore, one of the isolates, M2JP-3, was chosen for identification and test of the pathogenicity. The colony of M2JP-3 on PDA at 25°C for 5 days was white with yellow-brown pigmentation in the center (Figure 2A-B). From 10-day-old cultures grown on CLA (Fisher et al. 1982), macroconidia (n = 50) were falcate, slender, curved dorsiventrally, tapering towards both ends, 3 to 7 septate, and measured 24.5 to 52.1 x 3.7 to 4.7 μm. The microconidia (n = 50) were straight or slightly curved, septate 0 to 2, and measured 9.9 to 16.3 x 2.5 to 3.7 μm (Figure 2C-E). For molecular identification, genomic DNA was extracted using the method previously described (Khan et al. 2021),the internal transcribed spacer (ITS), translation elongation factor 1α (TEF1) and DNA-dependent RNA polymerase subunit II (RPB2) were amplified, respectively, using primers ITS1/ITS4 (White et al. 1990), EF1/ EF2 (O'Donnell et al. 1998), and 5F2/7cR (Reeb et al. 2004). The 529 bp (ITS), 723 bp (TEF1), and 965bp (RPB2) sequences were deposited in GenBank with acce. nos. OP303211, OP312675 and OP312674, respectively. A phylogenetic tree was constructed using the concatenated three gene sequences of M2JP-3 and that of the Fusarium incarnatum-equiseti species complex (FIESC) (Xia et al. 2019) based on Maximum Likelihood (Figure 3). M2JP-3 was grouped together with the F. pernambucanum strain NRRL 32864 (accession no. GQ505702 for ITS, GQ505613 for TEF1and GQ505791 for RPB2), and shared 100% concatenated sequence identity. For pathogenicity tests of M2JP-3, seeds of melon cultivar Jinmeiren were surface disinfected and sowed in soil in three replicated pots in a greenhouse at 26 °C under natural light. Healthy leaves of the melon plants were wounded with needles and inoculated with mycelial plugs of M2JP-3 or PDA plugs as control. . Symptoms similar to the original greenhouse symptoms were observed at 7 days after inoculation (Figure 4). The control leaves were asymptomatic. The same fungus was reisolated from the inoculated leaves, as identified based on morphology and molecular evidence, which confirmed the Kochs' postulates. To our knowledge, this is the first time Fusarium pernambucanum has been recorded causing leaf yellow spot disease on melon. Further, findings of the present study will help to develop effective disease management strategies against Fusarium pernambucanum Leaf Yellow Spot on melon in China.

First report of Didymella curtisii causing leaf scorch on spider lily (Hymenocallis littoralis) in China.

Hymenocallis littoralis (Jacq.) Salisb, commonly known as spider lily, is a Amaryllidaceae species widely cultivated in southern China for ornamental and medicinal purposes (Anusha et al., 2016). In 2020, there was a devastating outbreak of leaf scorch of H. littoralis from July to September in Kunming city, Yunnan province of China (E102.8268°, N24.8371°), with 97% disease incidence. The initial spots were small and reddish-brown but gradually expanded to large irregular lesions with yellow centers. The leaves then turned yellow and withered from tip towards the petiole in the severely infected plants. For identification, leaf sections (5 × 5 mm2) cut from the margins of the lesions were surface-sterilized for 3 min with 1% sodium hypochlorite, rinsed three times with sterile distilled water, placed on potato dextrose agar (PDA), and incubated at 28°C at a 12-h photoperiod for three days. One fungus was isolated from 90% of the samples, of which three monosporic isolates were selected using a method of agar dilution lineation separation. After 4 days of incubation, colonies were white-yellowish, and changed to beige-mustard after 7 days. The pycnidia were produced after 10 days incubation on oatmeal agar (OA), and they were black-brown, subglobose, and ostiolate. Chlamydospores mainly formed in the aerial mycelia, globose, often in chains, brown or pale. The conidia were ellipsoidal or clavate, (0-)1-3-septate, 2.1 to 10.8 × 1.0 to 3.2 μm (n=60). The total genomic DNA of three isolates was extracted from mycelia. The nuclear ribosomal internal transcribed spacer region (ITS), the second largest subunit of nuclear DNA-dependent RNA polymerase II (rpb2), the 28S nuclear ribosomal large subunit rRNA gene (LSU), and beta-tubulin gene (tub2) were amplified using the ITS1/ITS4 (White et al., 1990), fRPB2-5F/fRPB2-7cR (Liu et al., 1999), LR0R/LR5 (Schoch et al., 2012), and Btub2Fd/Btub4Rd (Woudenberg et al., 2009) primer pairs, respectively. The amplicons were cloned in the pMD19-T vector (Code No. 6013, Takara, Kusatsu, Japan) and sequenced bi-directionally. These three isolates had the same nucleotide sequences, one of which was submitted to NCBI (ITS, OM279485; rpb2, OM304305; LSU, OP800249; tub2, OQ108870). BLASTn analyses showed that ITS, rpb2, LSU, and tub2 were genetically 100%, 98.49%, 99.89%, and 97.89%, respectively, identical with MN973518, MT018130, MN943724, and MT005618 genes of Didymella curtisii strain CBS 288.29. Phylogenetic tree was constructed with MEGAX based on the nucleotide sequences of ITS, rpb2, LSU, and tub2 using the maximum likelihood method. The fungus isolated from diseased leaves of H. littoralis was grouped into the same clade with D. curtisii. According to the morphology and sequence analyses, the isolate was D. curtisii (Chen et al., 2015) and was named isolate HlDc1. To confirm the causal agent of the disease, a spore suspension with 106 spores of HlDc1/mL was smeared on healthy leaves of six months old with brushes. Leaves in the control group were smeared with sterile water. All inoculated plants were incubated at 28°C under a 12-h photoperiod in a moisture chamber. The pathogenicity tests were conducted three times with six plants each time. Fifteen days post-inoculation, the leaves inoculated with HlDc1 developed red-brown lesions, whereas the control leaves remained asymptomatic. Isolate HlDc1 was re-isolated from infected leaves. To our knowledge, this is the first report of leaf scorch on H. littoralis in Yunnan province, China, caused by D. curtisii. The results laid the foundation for epidemiological forecasting and scientific control of this disease.

First report of Fusarium concentricum as a causal agent of Fusarium leaf blotch on pecan (Carya illinoinensis) in Southeast China.

The economically important nut crop pecan (Carya illinoinensis (Wangenh.) K. Koch) is seriously affected by increasing incidence of fungal disease worldwide (Xiao et al 2021). The top leaves of the pecan variety 'Pawnee' in the orchard of Zhejiang A&F University, Zhejiang, China were damaged by massive dark brown plaques in summer to autumn 2021. The causal agent was isolated from leaves with target plaques following the steps: sterilized with 70% alcohol (30 s × 2), rinsed with sterilized water (3 ×) before and after 5% sodium hypochlorite (30 s), excised the plaques, and placed on PDA medium at 28℃ in a dark incubator for 3-d. The mycelium on the edge of each colony was transferred to fresh SNA medium in dark for 2 weeks to induce conidia formation. A few conidia-germinated mycelia were transferredand inoculated on new plates containing fresh PDA medium to obtain the purified cultures. Koch's postulates were applied to validate the pathogenicity of the purified isolates. Non-woundedly healthy leaves (disinfected with 5% sodium hypochlorite) of 'Pawnee' seedlings were inoculated with 5 mm 7-d old purified cultures. Dark-brown spots appeared on the leaves 2 days post inoculation at 25℃. The spots became larger accompanied by partially cracking and slight deformation of inoculated leaves from day 2 to day 4, while the control leaves remained asymptomatic. A re-isolated strain ZJ-6 from these infected leaves was identified as the pathogenic isolate with the same symptom as the previous one. Morphologically, aerial mycelia of the pathogenic isolate ZJ-6 cashmere and white. The reverse of colony orange. The edge of the colony appeared gradually thinner, the aerial mycelia loose and flocky, and the matrix mycelium whitened. Hyphae were septate, translucent with smooth wall and 1.47-7.14 µm in width. Microconidia (n = 20) obovoid to fusoid, mainly with 0-septate, 4.45-7.78×4.79-16.25 µm. Macroconidia (n = 20) sickle, mainly with 3-5 septa, 5.56-10.28×56.67-114.54 µm. Simultaneous of monophialidic and polyphialidic conidiophores. Conidiophore width 1.47-3.68 µm, slightly smaller than vegetative hyphae. The morphological characteristics matched with previous descriptions of Fusarium species (Nirenberg and O'Donnell 1998; Wang et al 2013). The identity of ZJ-6 was confirmed by phylogenetic reconstruction using the concatenated sequences of the ATP citrate lyase (ACL1), Calmodulin (CaM), the internal transcribed spacer (ITS) rDNA region, ribosomal RNA gene (LSU), the largest subunit of DNA-dependent RNA polymerase II (RPB1), partial translation elongation factor-1 alpha (TEF) and β-Tubulin (TUB). To this end, the genomic DNA of ZJ-6 was extracted by the M5 hipermix-MF859 (Mei5 Biotechnology) and submitted to GenBank under the accession numbers OP933646, OP933647, OP925890, OP925889, OP933396, OP933648, and OP933397, respectively. The obtained sequences of ZJ-6 were used for nucleotide BLAST against thetandard databases, respectively, and the strains with sequence identification values above 98% were selected to construct multiple alignment for building a phylogenetic tree. This analyses allowed the identification of ZJ-6 as Fusarium concentricum Nirenberg & O'Donnell, a species with few reports that can cause serious damage to the fruits and branches of other hosts (Hasan et al 2020; Huda-Shakirah et al 2020; Wang et al 2013). This is the first report of pathogenic F. concentricum on pecan in Southeast China that caused no harvest of infected plants.

First Report of Botrytis cinerea Causing Stem Rot on Pea (Pisum sativum L.) in China.

Pea (Pisum sativum L.) is one of the most important cool season legumes consumed as vegetable in the world. In March 2022, a severe stem rot was observed on pea cultivars in vegetative stage in Wuhan, Hubei Province, China (30°39' N, 114°66' E). The infection started on the lower stems, and the lesions were water soaked, then girdled the stem, resulting in wilting of the leaves. Eventually, the entire plant died, and some necrotic stems were covered with gray conidia. To investigate the causal agent, small pieces cut from diseased stems were surface sterilized with 2% NaOCl for 1 min, then incubated on potato dextrose agar (PDA) at 25°C for 3 days. Pure cultures were obtained by hyphal tip transfer and five isolates were studied further. Colonies initially appeared white, turned gray from the center, then became taupe with cottony aerial mycelia, and finally black hard, round or irregular sclerotia (0.92 to 5.34 × 0.86 to 4.42 mm, n = 20) developed. The sealing film of several plates were removed after 5 days, and abundant conidia were produced 3 days later. The conidia are terminally arranged at the end of long, grayish branched conidiophores, conidia are unicellular, hyaline and round or elliptical, (9.2 to 11.4 × 6.7 to 9.2 μm, n = 50), and the conidiophores are (10.7 to 13.0 μm × 760 to 1080 μm, n=20) in size. The morphological characteristics were consistent with descriptions of Botrytis cinerea (Li et al., 2016). Genomic DNA of the five isolates was extracted, and the internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate dehydrogenase (G3PDH) gene, heat-shock protein 60 (HSP60) gene, and DNA-dependent RNA polymerase subunit II (RPB2) gene were amplified using the primers described by Aktaruzzaman et al. (2018). The sequences were deposited in GenBank (accession nos. ON533694 and ON566787-ON566790 for ITS; ON600613 to ON600617 for HSP60; ON600608 to ON600612 for G3PDH; ON600603 to ON600607 for RPB2). The BLASTn analysis of these sequences showed that the isolates had high similarity (99 to 100%) with other B. cinerea isolates. A phylogenetic tree was constructed by MEGA11, and our isolates clustered in the B. cinerea clade. In pathogenicity test, 2-week-old seedlings of pea cultivar 'Zhongqin1' were inoculated. Mycelial plugs (5 mm diameter) taken from a 3-day-old colony of each isolate were placed on the axil of a stipule at the 4th node of potted pea plants (n=5 per isolate), and PDA plugs were placed on the same location of control (n=3). Inoculated and control plants were kept in a humid plastic box at 23°C for 2 days, and then placed in a glasshouse. Symptoms with water-soaked lesions were observed on the inoculated plants after 2 days, stems showed soft rot and broke off after 3 to 5 days, disease symptoms similar to those in the field, while the controls remained healthy. The pathogen was re-isolated from the affected stems, fulfilling Koch's postulates. B. cinerea had been reported to cause foliar, pod, seed and stem rot of pea after flowering in many pea production regions in the world (Kraft and Pfleger, 2001). Pea was recorded as a host of B. cinerea in Zhejiang, Sichuan and Yunnan Provinces (Tai, F. L. 1979; Zhuang, W.-Y. 2005; Zhang, Z. 2006.), but there has been no detailed disease description and identification of pathogen. To our knowledge, this is the first report of B. cinerea causing stem rot on pea in vegetative stage in China. Since B. cinerea can infect pea at any developmental stage, it could have a high economic impact as green pea production increases in China.

Fludarabine, a Potential DNA-Dependent RNA Polymerase Inhibitor, as a Prospective Drug against Monkeypox Virus: A Computational Approach.

Monkeypox is a zoonotic contagious disease that has recently re-emerged in different countries worldwide. Due to the lack of an effective treatment that eliminates the virus, there is an urgent need to find effective drugs to stop the spread of the multi-country outbreak. The current study aimed to use computational methods to quickly identify potentially effective drugs against the Monkeypox virus (MPXV). Three MPXV proteins were targeted in this study due to their essential role in viral replication (a DNA-Dependent RNA Polymerase subunit (A6R)), a protein involved in cell entry (D8L), and a protein catalyzing the envelopment of intracellular mature virus particles (F13L). We virtually screened a library of 1615 FDA-approved compounds, utilizing different in-silico approaches including computational modeling, molecular docking, molecular dynamic (MD) simulation, and MM-GBSA. The compound Fludarabine was found to have the best docking score (−7.53 kcal/mol) in relation to the MPXV A6R protein. Additionally, Fludarabine showed in-silico activity on the D8L and F13L proteins. During the whole period of the 100 ns MD simulation, the complex of A6R and Fludarabine exhibited the best stability. This stability was reflected in a good score of MM-GBSA, with an average value of −44.62 kcal/mole in a range between −53.26 and −35.49 and a low value of standard deviation (3.76). Furthermore, Fludarabine blocked efficiently the Asn175 residue which has an important role in the attachment of the virus to a host cell. The results of this study recommend more in vitro studies on this compound, as a starting point to develop a novel treatment against MPXV.

Leaf blight in Allium monanthum is caused by Botrytis squamosa in South Korea

In recent years, leaf blight has been observed on dalae (Allium monanthum) leaves at Seosan and Tehan regions in South Korea. Disease symptoms include necrotic spots, lesions, and blight on leaves. The pathogen responsible for the disease was successfully isolated from symptomatic leaf tissue using standard phytopathological procedures and identified. Based on morphological features coupled with sequence analyses of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) genes, fungal isolates were identified as Botrytis squamosa. The pathogenicity was confirmed by artificially inoculating both healthy detached leaves and whole plants of A. monanthum. To the best of our knowledge, this is the first report of leaf blight caused by B. squamosa in dalae in South Korea.

Botrytis cinerea as the causal agent of grey mould on floral tissue of mango in Japan

In March 2016, grey mould disease was observed on mango (Mangifera indica) in Okinawa Prefecture, Japan. During the flowering period, the disease caused a brown coloration of the petals and peduncles accompanied by white aerial mycelium. As the disease symptoms progressed, the rot of panicle parts was accompanied by grey mould, resulting in fruit set failure. A fungus was isolated from the discoloured inflorescence into pure culture. Based on morphology and analyses of glyceraldehyde-3-phosphate dehydrogenase (g3pdh), heat-shock protein 60 (hsp60) and DNA-dependent RNA polymerase subunit II (rpb2) DNA sequences the fungus was identified as Botrytis cinerea. In an inoculation test, the isolate reproduced the symptoms observed on mango petals and peduncles and was reisolated from the flowers. This is the first report of B. cinerea as the causal agent of grey mould (haiirokabi-byo in Japanese) on floral tissue of mango in Japan.

Root Rot of Codonopsis tangshen Caused by Ilyonectria robusta in Chongqing, China.

Codonopsis tangshen Oliv. belongs to the Campanulaceae, it is one of the most important economically medicinal materials in China.Which is used in medical and agricultural applications (Wu Q N, et al. 2020). In August 2019, root rot of C. tangshen was firstly observed in Fengjie, Chongqing city, southwest China (30°45' 59″ N; 109°36'36″ E; ), causing approximately 20% yield loss. At the initial stage of the disease, the above-ground stems and leaves turn yellow, and brown to black spots of different sizes appear at the base or root of the stem. With the further development of the disease, the above-ground leaves gradually turn yellow as the diseased spots rot from bottom to top, so that they die, and the diseased spots on the roots expand and begin to rot. Generally, they gradually rot from the bottom up, but the vascular bundles are occasionally normal. If the symptoms of C.tangshen started too late, and the root has not completely rotted by late autumn (late October to early November), the rest part of C.tangshen root will not continue to rot, and it is called half C.tangshen. In the next spring, the halfC. tangshen can continue to sprout, but it will continue to rot, which will seriously affect the yield and quality. In order to identify the pathogen, 25 samples of diseased plants were collected and symptomatic rhizome tissues were surface disinfected with 0.1% HgCl2 solution for 30s, rinsed in sterilized water 3 times, placed on potato dextrose agar (PDA), and incubated at 25℃±1°C in the dark. On the PDA, after seven days of culture, the center appeared light yellow, the edges were white, and the aerial hyphae were felt-like. The surface of the colony was reddish-brown and the margins were white and regular. The conidiophores were simple, usually born on the lateral or apical sides of aerial mycelium, unbranched, or minimally branched. Conidia were abundant, cylindrical, or rod-shaped, straight or slightly curved, usually with 1-3 septa. Macroconidia varied in size depending on the number of cells as follows: one-septate 15.3-26.3×4.2-7.3 μm（n=50）μm, two-septate 20.5-30.5×4.9-7.8μm (n=50), and three-septate 29.3-38.5×5.5-7.4 μm (n=50), round at both ends. For molecular identification, DNA was extracted from a representative isolate using a fungus genomic DNA extraction kit (Solarbio, Beijing, China). The internal transcribed spacer (ITS)(ITS1/ITS4, White, et al. 1990), beta-tubulin (TUB2)(BT2A/BT2B, O'Donnell and Cigelnik 1997), translation elongation factor 1-a (TEF) （ EF446F/EF1035R, Inderbitzin et al. 2005), DNA-dependent RNA polymerase subunit II gene(RPB2, O'Donnell K., et al. 2010 ) and histone H3(HIS3) (CYLH3F/CYLH3R, Crous, et al. 2004b) were amplified. BLAST results indicated that the ITS, TUB2, TEF, HIS3, and RPB2 sequences (GenBank MW392103, MW386994, MW386995 MW392103, and MW915473) showed 96% to 100% identity with Ilyonectria robusta sequences at NCBI (GenBank KU350726, JF335378, MN833103, MN833113, KM232336). The phylogenetic tree was inferred from the combined datasets (ITS, TEF1, TUB, and HIS3) from members of the I. robusta species complex analyzed in this study (Cabral et al. 2012 ). To complete Koch's postulates, a conidial suspension (106 spores/ml) collected from isolate CQ13 was irrigated onto fifteen annual C.tangshen potted plants. Sterile water was used as a negative control, and the pathogenicity assay was repeated three times. Following inoculation, the plants were cultured for 9 days at 75% relative humidity and 25 ℃. The inoculated plants showed symptoms similar to those observed in the field. In contrast, the negative control plants were healthy and unaffected. I. robusta was re-isolated from the infected tissues and identified by morphological characteristics and DNA sequence analysis. To our knowledge, this is the first report of I. robusta causing root rot disease of C.tangshen in China. Our results may help to take appropriate steps to control the disease in the commercial area ofC.tangshen. The authors declare no conflict of interest.

First Report of Sclerotinia Blight on Peanut Caused by Sclerotinia sclerotiorum in Qinghai Province, China.

Historically, peanut has not been produced in Qinghai province located in Northwest China because of the high elevation and cold climates. However, since 2020 field studies have been conducted to evaluate peanut cultivars for suitability to field production. In 2020, peanut cultivation was successful for the first time in Haidong city, Qinghai province, China. In August 2020, brown, irregular-shaped lesions were observed on peanut stems from Qinghai province in China. In the early stage, the watersoaked spots were formed on the stems, then lesions expanded rapidly and became brown. In advanced stages of the disease, stems became bleached and eventually died. The inside of the stems was rotten and hollow, and the diseased stem wilted and died. White hyphae and black irregular shaped sclerotia were observed on the infected stems. Finally, local or whole plant rotted and died at the end. Approximately 10% of the plants in a field were infected. Symptomatic stems were cut into small pieces, disinfected with 75% ethanol for 1 minute, 0.5% NaClO for two minutes, and sterile water for three times. Pieces then were plated on potato dextrose agar (PDA) media and incubated at 25°C in darkness. Fungal colonies were initially white, becoming gray, then black sclerotia (2.4 to 6.0 mm in diameter) were appeared at the edge of colonies. Genomic DNA of the pure cultures of an isolate (ZHX7) was extracted and PCR was carried out using glyceraldehydes-3-phosphate dehydrogenase gene (G3PDH) region primers G3PDH-F/G3PDH-R, heat-shock protein 60 gene (HSP60) region primers HSP60-F/HSP60-R, and DNA-dependent RNA polymerase subunit gene (RPB2) region primers RPB2-F/RPB2-R (Staats et al., 2005), respectively. G3PDH region (Accession No. MZ388475) showed 99.44% sequence identity (887 bp out of 909 bp) to Sclerotinia sclerotiorum (Accession No. AJ705044, 887 bp out of 887 bp). HSP60 region (Accession No. MZ388476) showed 99.90% sequence identity (972 bp out of 984bp) to S. sclerotiorum (Accession No. AJ716048, 972 bp out of 980 bp). RPB2 region (Accession No. MZ388477) showed 100.00% sequence identity (1096 bp out of 1129 bp) to S. sclerotiorum (Accession No. AJ745716, 1096 bp out of 1096 bp). Phylogenetic analysis was done using Neighbor-Joining (NJ) analysis based on those gene sequences. The isolate was identified as S. sclerotiorum based on molecular analysis and morphological characteristics. For pathogenicity assay, ten-days-old potted peanut (Luhua No.12) seedlings were inoculated with one mycelial plug (8 mm in diameter ) by placing the inoculum on the base of the stem in a growth chamber (30°C in the day and 25°C at night, a 12-h photoperiod and 80% RH). All inoculated seedlings exhibited typical basal stem rot, and root showed different degrees of damage, and wilted 5 days after inoculation. No symptoms were observed on control plants treated with sterile distilled mycelial plugs, and S. sclerotiorum was consistently re-isolated from symptomatic tissue. S. sclerotiorum has been reported on peanut in Northeastern China (Yan et al., 2005). To our knowledge, this is the first report of S. sclerotiorum causing Sclerotinia Blight on peanut in Qinghai province, China. The peanut planting area in Qinghai has been further expanded this year, and S. sclerotiorum has a broad host range (Boland and Hall, 1994), so Sclerotinia Blight is a potential threat to peanut production, and as a result, it is critical for commercial producers to monitor plants for S. sclerotiorum.

First Report of Post-Harvest Gray Mold on Hyacinth Bean (Lablab purpureus) Caused by Botrytis cinerea in Korea.

Hyacinth bean (Lablab purpureus L.) is a highly proteineous legume under the family Fabaceae. It is native to Africa, cultivated throughout the world, and recently introduced vegetable in Korea. In April 2020, approximately 10 to 15% of the total harvested pods showed gray mold rot symptoms after 3-5 days of storage at 4 °C in Jeonju, Jeonbuk province, Korea. The symptoms observed were irregular, water-soaked spots become brown or gray with white hyphae were appeared on the infected pods. Diseased tissue was excised, and surface sterilized by immersing in 1% sodium hypochlorite (NaOCl) for 1 min, rinsed three times with sterilized distilled water, placed on potato dextrose agar (PDA) plates, and incubated at 20 ± 2°C for 7 days. A total of five morphologically similar fungal isolates (HBGM001 to HBGM005) were obtained from diseased samples; isolate HBGM002 and HBGM005 were selected for identification. The fungus produced initially white colonies, after 7 days it changes to gray to dark colonies with dark mycelium that sporulated abundantly on PDA at 20ºC. The conidia (n = 50) were single-celled, ellipsoid or ovoid in shape, and 6.11 to 13.9 × 4.8 to 9.4 μm in size for HBGM001 isolate and 5.81 to 14.1× 4.5 to 9.6 μm in size for HBGM005. Conidiophores (n = 15) arose solitary or in groups, straight or flexuous, septate, with an inflated basal cell brown to light brown, and measured 103 to 420× 7 to 25 μm for HBGM001 isolate and 101 to 415 × 5 to 23 μm for HBGM005 isolate. After two weeks, the fungus formed several black sclerotia (n = 20) ranging from 0.5 to 4.2 × 0.5 to 3.4 mm for HBGM001 isolate and 0.4 to 4.4 × 0.3 to 3.3 mm for HBGM005 isolate near the edge of the Petri dish. Morphological characters were consistent with those of Botrytis cinerea Pers.: Fr. (Ellis 1971). As for molecular identification, the internal transcribed spacer (ITS) and three nuclear protein-coding genes (glyceraldehydes-3-phosphate dehydrogenase gene [G3PDH], heat-shock protein 60 gene [HSP60], and DNA-dependent RNA polymerase subunit gene [RPB2]) were amplified using primer pairs ITS1/ITS4 (White et al. 1990), G3PDH-F/G3PDH-R, HSP60-F/HSP60-R, and RPB2-F/RPB2-R (Staats et al. 2005), respectively. The ITS, G3PDH, HSP60, and RPB2 sequences of HBGM002 and HBGM005 isolates (GenBank accession number MT439648 and MT968495 for ITS; MT439649 and MT968496 for G3PDH; MT439650 and MT968497 for HSP60; MT439651 and MT968498 for RPB2 respectively) were 99% to 100% identical to those of B. cinerea (KY364366, KF015583, KJ018758, and KJ018756, respectively). To determine pathogenicity, five disinfected pods were pinpricked (3 sites per pod) with sterile needles and 50 µl of conidial suspension (1 × 105 conidia/ml) was inoculated by pipetting into the wounds. An analogous five pods, serving as controls, were inoculated with sterile distilled water. All the pods were placed in a growth chamber and maintained a temperature of 20±2ºC and a relative humidity >80%. After 5 days, gray mold symptoms developed on the inoculated pods, whereas no symptoms appeared on control pods. The pathogen was re-isolated from the inoculated pods, fulfilling Koch's postulates. B. cinerea has been reported causing gray mold in Hyacinth bean in China, Taiwan and India (Farr and Rossman 2021). To our knowledge, this is the first report of B. cinerea causing post-harvest gray mold on hyacinth bean in Korea. The disease could represent a threat for hyacinth bean post-harvest and storage and management strategies should be investigated and applied.

Peculiar evolution of the Monkeypox virus genomes

We compare the evolution of 14 genomes of monkeypox viruses including that of May 2022 that is currently spreading among humans in numerous countries outside Africa. Our aim was to discover mutations and other viral evolutions (recombination) of the virus genome that may explain the sudden impact of this epidemic circulating at very low-level and alert on its potential pathogenic character. We have evidenced the presence of a succession of a large number of T bases between the DNA-dependent RNA polymerase subunit rpo132 and the cowpox A-type inclusion protein, progressively rising from the absence of a characteristically long pattern of T-bases found in succession (≤ 10) in the early genomes of 1971, up to the 19 T-base sequence in the Israel 2018 reference strain and the 30 T bases thereafter in the 2022 strains. We find a complementary match for this long sequence of T bases only in the simian hemorrhagic encephalitis virus, at the 3’ end of the genome with a long succession of 28 A-bases after the stop codon. More strikingly, we find that the corresponding 10 phenyl-alanine aa chain is reported as matching uniquely (E≤0.001) a hypothetical protein element in Plasmodium falciparum, Yersinia pestis, Escherichia coli and Penicillium nordicum. We wonder whether this region of the monkeypox genome situated right upstream this long T-repeat may potentially code for a not yet identified polypeptide sequences with a functional role.

First Report of Leaf Spot Caused by Botrytis cinerea on Cardamine hupingshanensis in China.

Cardamine hupingshanensis is a selenium (Se) and cadmium (Cd) hyperaccumulator plant distributed in wetlands along the Wuling Mountains of China (Zhou et al. 2018). In March of 2020, a disease with symptoms similar to gray mold was observed on leaves of C. hupingshanensis in a nursery located in Changsha, Hunan Province, China. Almost 40% of the C. hupingshanensis (200 plants) were infected. Initially, small spots were scattered across the leaf surface or margin. As disease progressed, small spots enlarged to dark brown lesions, with green-gray, conidia containing mold layer under humid conditions. Small leaf pieces were cut from the lesion margins and were sterilized with 70% ethanol for 10 s, 2% NaOCl for 2 min, rinsed with sterilized distilled water for three times, and then placed on potato dextrose agar (PDA) medium at 22°C in the dark. Seven similar colonies were consistently isolated from seven samples and further purified by single-spore isolation. Strains cultured on PDA were initially white, forming gray-white aerial mycelia, then turned gray and produced sclerotia after incubation for 2 weeks, which were brown to blackish, irregular, 0.8 to 3.0 × 1.2 to 3.5 mm (n=50). Conidia were unicellular, globose or oval, colourless, 7.5 to 12.0 × 5.5 to 8.3 μm (n=50). Conidiophores arose singly or in group, straight or flexuous, septate, brownish to light brown, with enlarged basal cells, 12.5 to 22.1 × 120.7 to 310.3 μm. Based on their morphological characteristics in culture, the isolates were putatively identified as Botrytis cinerea (Ellis 1971). Genomic DNA of four representative isolates, HNSMJ-1 to HNSMJ-4, were extracted by CTAB method. The internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate dehydrogenase gene (G3PDH), heat-shock protein 60 gene (HSP60), ATP-dependent RNA helicaseDBP7 gene (MS547) and DNA-dependent RNA polymerase subunit II gene (RPB2) were amplified and sequenced using the primers described previously (Aktaruzzaman et al. 2018) (MW820311, MW831620, MW831628, MW831623 and MW831629 for HNSMJ-1; MW314722, MW316616, MW316617, MW316618 and MW316619 for HNSMJ-2; MW820519, MW831621, MW831627, MW831624 and MW831631 for HNSMJ-3; MW820601, MW831622, MW831626, MW831625 and MW831630 for HNSMJ-4). BLAST searches showed 99.43 to 99.90% identity to the corresponding sequences of B. cinerea strains, such as HJ-5 (MF426032.1, MN448500.1, MK791187.1, MH727700.1 and KX867998.1). A combined phylogenetic tree using the ITS, G3PDH, HSP60 and RPB2 sequences was constructed by neighbor-joining method in MEGA 6. It revealed that HNSMJ-1 to HNSMJ-4 clustered in the B. cinerea clade. Pathogenicity tests were performed on healthy pot-grown C. hupingshanensis plants. Leaves were surface-sterilized and sprayed with conidial suspension (106 conidia/ mL), with sterile water served as controls. All plants were kept in growth chamber with 85% humidity at 25℃ following a 16 h day-8 h night cycle. The experiment was repeated twice, with each three replications. After 4 to 7 days, symptoms similar to those observed in the field developed on the inoculated leaves, whereas controls remained healthy. The pathogen was reisolated from symptomatic tissues and identified using molecular methods, confirming Koch's postulates. B. cinerea has already been reported from China on C. lyrate (Zhang 2006), a different species of C. hupingshanensis. To the best of our knowledge, this is the first report of B. cinerea causing gray mold on C. hupingshanensis in China and worldwide. Based on the widespread damage in the nursery, appropriate control strategies should be adopted. This study provides a basis for studying the epidemic and management of the disease.

Characterization of Botrytis cinerea and B. prunorum From Healthy Floral Structures and Decayed 'Hayward' Kiwifruit During Post-Harvest Storage.

Gray mold is the primary postharvest disease of 'Hayward' kiwifruit (Actinidia deliciosa) in Chile, with a prevalence of 33.1% in 2016 and 7.1% in 2017. Gray mold develops during postharvest storage, which is characterized by a soft, light to brown watery decay that is caused by Botrytis cinerea and B. prunorum. However, there is no information on the role of B. prunorum during the development and storage of kiwifruit in Chile. For this purpose, asymptomatic flowers and receptacles were collected throughout fruit development and harvest from five orchards over two seasons in the Central Valley of Chile. Additionally, diseased kiwifruits were selected after storage for 100 days at 0°C and 2 days at 20°C. Colonies of Botrytis sp. with high and low conidial production were consistently obtained from apparently healthy petals, sepals, receptacles, and styles and diseased kiwifruit. Morphological and phylogenetic analysis of three partial gene sequences encoding glyceraldehyde-3-phosphate dehydrogenase, heat shock protein 60, and DNA-dependent RNA polymerase subunit II were able to identify and separate B. cinerea and B. prunorum species. Consistently, B. cinerea was predominantly isolated from all floral parts and fruit in apparently healthy tissue and diseased kiwifruit. During full bloom, the highest colonization by B. cinerea and B. prunorum was obtained from petals, followed by sepals. In storage, both Botrytis species were isolated from the diseased fruit (n = 644), of which 6.8% (n = 44) were identified as B. prunorum. All Botrytis isolates grew from 0°C to 30°C invitro and were pathogenic on kiwifruit leaves and fruit. Notably, B. cinerea isolates were always more virulent than B. prunorum isolates. This study confirms the presence of B. cinerea and B. prunorum colonizing apparently healthy flowers and floral parts in fruit and causing gray mold during kiwifruit storage in Chile. Therefore, B. prunorum plays a secondary role in the epidemiology of gray mold developing in kiwifruit during cold storage.

Botrytis polygoni, a new species of the genus Botrytis infecting Polygonaceae in Gansu, China

ABSTRACT A new species, Botrytis polygoni, was isolated from several species of Polygonaceae in 2011 and 2012 in Tongwei County, Gansu Province, China. The species infects Fagopyrum esculentum, F. tataricum, and Fallopia convolvulus, causing brown leaf spots and large blotches with concentric rings in the field. Botrytis polygoni is morphologically characterized by conidia spherical, unicellular, hyaline to pale brown or brown, (10.2–)14.3–21.4(–23.5) μm; and sclerotia black, spherical to subspherical, allantoid, or irregular-shaped, 0.2–4.1 × 0.1–3.0 mm. Comparison of the nuc rDNA internal transcribed spacer region (ITS1-5.8S-ITS2) sequences confirmed its placement in the genus Botrytis. Phylogenetic analysis based on the protein-coding genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) showed that the new species is clustered close but separate from Botrytis pyriformis, which was distant from 37 other Botrytis species and 17 undescribed species. Pathogenicity tests showed that the new species has aggressive pathogenicity to four species of Polygonaceae, specifically Fag. tataricum, Fal. convolvulus, Polygonum sibiricum, and Pol. aviculare, weak pathogenicity to Vicia faba in the Fabaceae, and no pathogenicity to eight other tested plants: Amaranthus retroflexus, Cirsium arvense, Convolvulus arvensis, Kalanchoe blossfeldiana, Lagopsis supine, Mentha canadensis, Plantago asiatica, and Raphanus sativus.

Botrytis cinerea causing gray mold of Polygonatum sibiricum (Huang Jing) in China

Polygonatum sibiricum is a traditional Chinese medicinal herb and can also be used as tea and ornamental plant. During 2016 to 2018, a disease with symptoms similar to gray mold was extensively observed on leaves of P. sibiricum in the Sichuan Province of China. The pathogen was isolated from the diseased plants and identified as Botrytis cinerea based on the morphological features and Internal transcribed spacer (ITS), DNA dependent RNA polymerase subunit II gene (RPB2), heat-shock protein 60 gene (HSP60) and ATP-dependent RNA helicase DBP7 gene (MS547) all of which showed 99.89%–99.91% identities to the reported B. cinerea strains. Pathogenicity was confirmed through inoculation experiments fulfilling Koch's postulates. To our knowledge, this is the first report of B. cinerea causing gray mold disease on P. sibiricum in China.

First Report of Gray Mold on Jinxianlian (Anoectochilus roxburghii) Caused by Botrytis cinerea in China

Anoectochilus roxburghii is one of the important herbal medicines in China. As a national rare and endangered plant, A. roxburghii is presently cultivated in bottles through greenhouse productions. The cultivation of A. roxburghii in Zhejiang Province accounts for a large proportion in China. Gray mold was found to severely affect the production of A. roxburghii. In 2018, the incidence of gray mold indicated by water-soaked gray mold symptoms with white to gray mycelia and conidiogenous apparatus on infected stems and leaves was observed for 6% of seedling bottles. When the conditions are suitable, gray mold spreads to the whole leaf and then gradually turns into grayish black and produces brown dead plaque, which causes the plant to wrinkle in severe cases. Thirty-one diseased leaves collected from different greenhouses in Jinhua City were picked with a needle on 2% potato dextrose agar (PDA) and cultured in the dark at 23°C. The colonies on the PDA were initially grayish white, followed by brownish black, and produced one-celled, round conidia (8.78 ± 0.4 × 12.60 ± 0.3 μm). These morphological features are consistent with Botrytis cinerea. In order to confirm the identification based on morphological features, DNA-dependent RNA polymerase subunit II (RPB2), heat-shock protein 60 (HSP60), and glyceraldehyde-3-phosphate (G3PDH) were amplified from the DNA extracted from the mycelium produced on PDA (Berbee et al. 1999; Liu et al. 1999; Smith 1989). The sequences were deposited in NCBI under accession numbers RPB2 (MN464111, MN464112, MN464113), HSP60 (MN464108, MN464109, MN464110), and G3PDH (MN464105, MN464106, MN464107). BLAST analysis of the RPB2 (1,106 bp) segment showed 100% identity to the RPB2 sequence of B. cinerea isolate S4GBR40 (GenBank accession no. MK3880531). The HSP60 (956 bp) segment showed 100% identity to the HSP60 sequence of B. cinerea isolate F2-17 (GenBank accession no. MK256903). And the G3PDH (994 bp) gene segment showed 100% identity to B. cinerea isolate GZFQ-1 (GenBank accession no. MH479930). Phylogenetic analysis based on RPB2, HSP60, and G3PDH showed that the pathogen was B. cinerea. Uninfected A. roxburghii healthy plants were sprayed with 2 × 10⁶ conidia/ml in distilled water as inoculum, and plants inoculated with only distilled water were adopted as the blank control. For each isolate, 16 intact plants were inoculated. Plants were then kept at 25°C and 95% relative humidity in a 12-h light/dark incubation. After 10 days, all three tested isolates caused gray mold symptoms on A. roxburghii, whereas no symptoms appeared in the controls. Cultures reisolated from lesions and cultured on PDA exhibited the same morphological characteristics as B. cinerea (Carmichael et al. 2019), confirming Koch’s postulates. The inoculations were performed twice. To the best of our knowledge, this is the first report of the gray mold in A. roxburghii, which is the main factor limiting its productions. Measures must be taken to manage the disease in a timely manner.