Blight Research Articles

Northwestern Himalayan common beans: A Treasure Trove for breeding resistant bean cultivars for multiple foliar pathogens

Common bean (Phaseolus vulgaris. L) is attacked by a lot of important foliar diseases like anthracnose, Bean Common Mosaic Virus, angular leaf spot, Bean Golden Yellow Mosaic Virus, and common bacterial blight. In the present study, we exploited anthracnose resistant germplasm of 122 common bean genotypes for the identification of broad spectrum and durable resistance for multiple foliar diseases. We utilized linked molecular markers and found some promising genotypes with 11 resistance genes. These genotypes possess significant potential as parental lines for gene pyramiding strategies, to enhance disease resistance in common beans. We also highlighted the need for new generation markers over SCAR markers to streamline genotypic screening and expedite the breeding of disease-resistant common bean varieties. Our phenotypic studies identified a few bean landraces highly resistant to the new BCMV NL-1n strain. Consequently, the genome wide association study also confirms the presence of already identified resistance genes. Additionally, our study reconfirms the presence of the recently identified bc-urgene in our material. The bean landraces of northern India contain novel regions associated with BCMV resistance on Pv03, Pv05, Pv04, Pv06, Pv07, Pv09, and Pv11. This study provides the list of bean genotypes that can be used to breed resistant cultivars and may also contain new resistance genes to a most important viral disease of common beans.

First report of leaf blight of water chestnut (Trapa natans L.) caused by Sclerotium hydrophilum in central China.

Trapa natans L., or water chestnut, is a currently globally distributed aquatic plant. The Yangtze River basin in China, a site origin of water chestnut (Fan et al., 2022), has extensive cultivation as a vegetable. In June 2021, a survey at the National Aquatic Vegetable Resource Garden in Wuhan, Hubei, China, revealed browning and wilting of water chestnut plants, with abundant white mycelia and brown to black sclerotia on leaves, indicative of southern blight (Sclerotium rolfsii). Field disease incidence a 1 ha area reached 70%, reducing fruit yield by 50%. About 10% of diseased plants showed blackening and rot from petioles to leaves. White sclerotial primordia and small brown to black sclerotia formed on the plant surfaces. By late August, symptoms exceeded 60%. To identify the pathogen, isolations were made from 243 sclerotial samples using 75% alcohol to disinfect, rinsed three times with water, and then incubated on potato dextrose agar (PDA) at 25℃. A total of 129 isolates were obtained, most of which exhibited characteristics of S. rolfsii. However, 21 isolates had sclerotia significantly smaller than those of S. rolfsii (1 to 1.5 mm in diameter). These isolates, cultured on PDA, produced abundant fluffy white aerial hyphae, 3 to 6 μm wide. Optimal mycelium growth was between 25 °C to 30 °C, with an average daily rate of 10 mm. White to light brown sclerotia appeared after 5 days and turned black within 10 to 14 days, averaging 0.34 mm in diameter (n=50). Some isolates produced a light brown pigment. These traits matched the description of S. hydrophilum (Bashyal et al. 2021). Isolates 221 and 238 were selected for molecular identification, with genomic DNA extracted from mycelia using the CTAB method. PCR amplification was conducted using ITS1/ITS4 and NS1/NS6 primers to target the internal transcribed spacer (ITS) and the small subunit ribosomal RNA gene (ssrRNA). Sequence analysis showed that the ITS sequence of isolate 221 (GenBank Acc. No. OR512512) had 99.84% sequence identity with S. hydrophilum Msh6 (GenBank Acc. No. FJ595946), and isolate 238 (GenBank Acc. No. PP035993) had 99.72% identity with S. hydrophilum Whcc-4 (GenBank Acc. No. PP035994). The ssrRNA sequences of both isolates (GenBank Acc. No. PP237261) had 99.69% identity with S. hydrophilum strain Hbq001 (GenBank Acc. No. KY995575), confirming their identification as S. hydrophilum. To assess pathogenicity, 16 water chestnut plants (cultivar Jia-yu Ling) at the rosette stage were placed individually in 32 cm diameter, 10 cm deep containers with fresh water. Eight plants were inoculated with 50 mature sclerotia from PDA cultures of isolates 221 and 238, and incubated at 25 °C for 14 days, with four plants per isolate. The remaining eight plants served as controls. Containers were covered to maintain 100% relative humidity at 25 °C to 32 °C for 3 days. This procedure was repeated twice. After 7 days, inoculated plants developed dark brown lesions on petioles that spread to leaves by 15 days post-inoculation. Fungi isolated from diseased leaves resembled isolates 221 and 238, fulfilling Koch's postulates. S. hydrophilum infecting at least 19 genera of plants, including rice (Zhong et al. 2018), wild rice, water lily (Kernkamp et al. 1977) and watershield (Fu et al. 2024). This is the first report of S. hydrophilum infecting water chestnut (T. natans) in central China, identifying it as a co-pathogen with S. rolfsii. Their combined presence may heighten plant mortality and threaten water chestnut cultivation.

Screening of Inbred Lines of Maize against Turcicum Leaf Blight (Exserohilum turcicum) under Artificial Epiphytotic Conditions

Aims: Turcicum Leaf Blight (TLB), caused by Exserohilum turcicum, significantly affects maize in Karnataka, leading to yield losses of up to 70% in severe cases. To develop tolerant genotypes against this disease, an experiment was conducted using 100 inbred lines collected from the IMIC maize field day in Hyderabad. Study Design: Investigation was carried using Randomized complete block design with two replication. Place and Duration of Study: Maize Research Centre and Seed Farm, Devihosur during kharif-2022. Methodology: One hundred inbred lines were screened against TLB disease. among them 10 resistant lines were selected based on their maturity, disease reaction, grain yield and per se performance. These inbreds along with the checks (Resistant check CI-4 and Susceptible Check CM-202) were sown in Kharif 2022 at Maize Research Centre and Seed Farm Devihosur, UAS, Dharwad. Artificial inoculation was performed 45 days after sowing in the leaf whorls using infected leaves with TLB and the results were evaluated at the silk drying stage. To assess the disease reaction to TLB, we used 1 to 9 scale as established by the Indian Institute of Maize Research, Ludhiana (Anon., 2016). Lines that received disease scores between 1.0 and 3.0 were classified as resistant (R), scores of 4 to 5 as moderately resistant (MR), scores of 6 to 7 as moderately susceptible (MS), and scores of 8 to 9 as susceptible (S). Results: The performance of these lines were compared with the resistant check CI-4 and susceptible check CM-202. Screening trial revealed that out of hundred inbred lines, eighteen lines Showed highly resistant reaction. This information can be useful for selection of parents and to develop tolerant hybrids in breeding programs or utilize them as source of resistance.

Marker Assisted Selection in Advanced Backcross Population of Rice Variety, MTU1010 for Bacterial Blight and Blast Resistance

The present study was aimed for identification of the bacterial blight and blast resistant lines in the advanced back cross population of MTU-1010 using marker assisted foreground selection and also for evaluation of agro-morphological characters. The M-16-59 introgressed line (derived from an intercrossing of BC2F1 plants of MTU-1010 x GPP2 and MTU-1010 x NLR 145) is developed under ongoing DBTDBSRR subproject -IV possessing Xa21, xa13, Pi1 and Pi54 resistance genes having broad spectrum resistance to bacterial blight and blast is used as a donor parent and MTU-1010 was used as a recurrent parent for the back cross. Before attempting the backcross both the parents were verified for the target genes along with the original donors GPP2 and NLR 145 using gene specific/linked molecular markers viz., xa13-promo for xa13 gene, pTA248 for Xa21 gene, RM 224 for Pi1 and Pi54 MAS for Pi54. under the F1 generation (equivalent to BC3F1 because two backcrosses were completed earlier), 120 plants were screened, and 16 plants were confirmed for xa13, Xa21, Pi1, and Pi54 genes under heterozygous conditions. These confirmed plants were assessed for agro-morphological characteristics such as yield, grain features, and plant type. The results showed that the confirmed heterozygous plants were comparable to MTU-1010 and passed to the next round of selection and evaluation. The BC1F1-198th plant (96.8%) was selfed to produce BC1F2 population. Twenty five plants were advanced to BC1F3 generation based on BB resistance and above other phenotypic characters. The selected BC1F3 progenies were screened for blast and BB resistance. Four BC1F3 progenies with four target genes (xa13xa13Xa21Xa21Pi54Pi54Pi1Pi1) showed very high level of resistance to both the diseases. BC1F2-198-52nd line found similar to MTU1010 with respect to yield and yield related characters besides showing resistance to both BB and blast.Improved lines of MTU1010 can be advanced for multi-location testing under All India Coordinated Rice Improvement Project (AICRIP) for their evaluation and possible release for the benefit of rice farmers.

Phosphatidylcholine Transfer Protein OsPCTP Interacts with Ascorbate Peroxidase OsAPX8 to Regulate Bacterial Blight Resistance in Rice

Rice phosphatidylcholine transfer protein (PCTP), which contains a steroidogenic acute regulatory protein-related lipid transfer (START) domain, responds to bacterial blight disease. Overexpression of OsPCTP quantitatively enhances resistance to pathogen in rice, whereas depletion of it has the opposite effect. Further analysis showed that OsPCTP physically interacts with OsAPX8, a ROS scavenging enzyme, and influences ascorbate peroxidase enzymatic activity in vivo. In addition, the expression of pathogenesis-related genes PR1a, PR1b and PR10 were significantly induced in OsPCTP-OE plants compared with that in wild-type plants ZH11. Taken together, these results suggested that OsPCTP mediates bacterial blight resistance in rice through regulating the ROS defense pathway.

The Management of Fungal Diseases in Organic Production Systems Through a Mixture of Durum Wheat Varieties

Fungal diseases are a yield-limiting factor for wheat. Their management in organic production systems is one of the prevailing challenges because it must be based mainly on indirect measures through agricultural practices. Variety mixtures are one of these practices, a concept that has been demonstrated to improve several factors affecting yield. Recently, it has become a practice that enables sustainability in agriculture. Our research aim is to evaluate the capacity of this practice to control three fungal diseases (foliar and ear) on durum wheat. This study was conducted over two consecutive years (2019 and 2020) at two locations: a certified organic farm in the Benslimane region (2019) and the National School of Agriculture farm in Meknes (2020). Four durum wheat varieties (Isly, Tarek, Karim, and Nassira) were used to create the mixture. The parameters that were monitored were the disease severity, the grain yield, and its components. The analysis of variance for the three fungal diseases’ severity was significant. The variety that showed resistance to all diseases was the Isly variety, and the most susceptible variety was the Nassira variety. The resistance of the other varieties to the diseases was variable from one year to the other. The mixture showed average severity values. It allowed a reduction in the severity of leaf rust of 47% during the first year and 30% during the second year compared to the most susceptible variety (Nassira). In the case of HLB (helminthosporiosis leaf blight), it reduced the disease by 47% during the first year and 34% during the 2020 season. For ear disease, Fusarium head blight (FHB), the reduction was 68% during the year 2019 and 49% during 2020. The mixture also ensured yield stability between the two trial years (1.66 t ha−1 and 1.54 t ha−1).

Baseline Sensitivity and Toxicity Mechanisms of Prochloraz to Alternaria alternata Strains Associated with Maize Leaf Blight in Heilongjiang Province in China.

Alternaria species are fungal pathogens that can infect maize, causing leaf blight disease and significant economic losses. This study aimed to determine the baseline sensitivity to prochloraz of A. alternata isolates obtained from diseased maize leaves collected from Heilongjiang Province by assessing the half-maximal effective concentration (EC50) values. The EC50 values of prochloraz ranged from 0.0550 to 2.3258 μg/ml, with an average of 0.9995 ± 0.5192 μg/ml. At EC50 (1.2495 μg/ml) and 2EC50 (2.4990 μg/ml), prochloraz increased the number of mycelial offshoots, disrupted the cell membrane integrity of conidia and mycelia, and resulted in a reduced ergosterol content in the mycelia. Prochloraz significantly affected the mycelial cell membrane permeability and increased the malondialdehyde content and superoxide dismutase activity. No cross-resistance was detected between prochloraz and other fungicides. These data demonstrate that prochloraz is a promising fungicide for managing maize leaf blight caused by A. alternata and provide novel insights into understanding the mechanism of prochloraz toxicity against A. alternata isolates.

Efektivitas Asap Cair Kayu Rambutan dalam Menghambat Pertumbuhan Colletotrichum sp Secara In Vitro

Leaf blight is one of the main diseases in oil palm nurseries, as a result of the attack of the pathogen Colletotrichum sp. The initial symptoms are found on the edges of the leaves. Colletotrichum sp. is a pathogenic fungus that causes blight in oil palm, so it needs to be controlled. One of the alternative controls is by using rambutan wood liquid smoke. This study aims to obtain an effective concentration of rambutan wood liquid smoke that can inhibit the growth of Colletotrichum sp. in vitro. This research was carried out from November 2023 to January 2024 at the Laboratory of Pathology, Entomology, Microbiology and Soil Science, Faculty of Agriculture and Animal Husbandry, Sultan Syarif Kasim State Islamic University, Riau. This study used an experimental method with a complete randomized design (RAL) with 6 treatments (0%, 1%, 2%, 3%, 4% and 5%) with each treatment repeated 4 times, so that there were 24 experimental units. Observation parameters include total phenol analysis and PH test of liquid smoke, macroscopic, growth rate (cm/day) and inhibition (%) Colletotrichum sp. The results showed a total phenol content of 3.47% and a PH test. Rambutan wood liquid smoke with a concentration of 4% is very effective in inhibiting Colletotrichum sp. 100% inhibition and growth rate of 0 cm/day.

Application of deep learning for rice leaf disease detection in the Mekong Delta

The Mekong River Delta, the largest rice-producing region in Vietnam with an annual output of over 25 million tons, plays a vital role in ensuring food security both within the country and globally. In recent years, it has undergone significant transformation in rice cultivation, which aims to support farmers here to plant rice more effectively. However, severe weather conditions and soil degradation have negatively impacted rice growth. Additionally, rice is highly susceptible to various diseases that must be identified and prevented promptly. As a result, leveraging technology such as AI and deep learning to diagnose rice diseases based on leaf symptoms is essential. This paper utilizes an image dataset of three common rice leaf diseases—leaf smut, brown spot, and bacterial leaf blight—and applies deep learning networks (MobileNet and ResNet) to evaluate and select the best model. A diagnostic program is then developed to detect these diseases. Experimental results show that the MobileNetV3-Small model (a variant of the MobileNet network) is the most optimal, offering fast training time, high accuracy, and acceptable levels of loss and error.

First report of Exserohilum turcicum causing leaf blight on sudangrass (Sorghum × drummondii) in Mexico

In February 2021, elongated grey lesions with reddish margin were observed on sudangrass (Sorghum × drummondii) leaves, in the municipality of Guasave, Sinaloa, Mexico. These symptoms resembled those of leaf blight caused by Bipolaris and Exserohilum on other grasses. Two fungal isolates were recovered from symptomatic leaves, and their identities were confirmed based on a polyphasic approach. The morphological and phylogenetic analysis of the actin gene (act) and internal transcribed spacer region (ITS) of both isolates revealed their identity as Exserohilum turcicum. A pathogenicity test with a representative isolate confirmed this fungus as the causal agent of leaf blight on sudangrass, as symptoms previously observed in the field were developed on the inoculated plants. The E. turcicum isolate was recovered from the diseased sudangrass plants, fulfilling Koch’s postulates. This is the first report of E. turcicum causing leaf blight on sudangrass in Mexico.

Luteibacter sahnii sp. nov., A Novel Yellow-Colored Xanthomonadin Pigment Producing Probiotic Bacterium from Healthy Rice Seed Microbiome.

To explore the rice seed microbiome, our objective was to isolate novel strains of Xanthomonas, a plant-associated bacterium with diverse lifestyles. Four isolates, anticipated to be Xanthomonas based on morphological features of yellow colonies, were obtained from healthy rice seeds. Phylo-taxono-genomic analysis revealed that these isolates formed monophyletic lineages belonging to a novel species within the genus Luteibacter. Pairwise ortho Average Nucleotide Identity and digital DNA-DNA hybridization confirmed their distinct species status. We propose Luteibacter sahnii sp. nov. as a novel species, with PPL193T = MTCC 13290T = ICMP 24807T = CFBP 9144T as the type strain and PPL201, PPL552, and PPL554 as other constituent members. The fatty acid profile of the type strain is dominated by branched fatty acids like Iso-C15:0, consistent with other members of the genus. The novel species displays non-pathogenic attributes and exhibits plant probiotic properties, protecting rice plants from the leaf blight pathogen X. oryzae pv. oryzae. Production of Indole-3-Acetic Acid (IAA) and genomic regions encoding anti-microbial peptides emphasize its potential contributions to plant hosts. This study underscores the importance of employing a combination of phenotypic and genotypic methods in culturomics to enhance our understanding of rice seed microbiome diversity.

Experimental evaluation of effectiveness of genomic selection for resistance to northern corn leaf blight in maize.

Northern corn leaf blight (NLB) caused by Setosphaeria turcica (Luttrell) Leonard & Suggs is a severe foliar disease in maize. Resistance to NLB is complexly inherited and controlled by several quantitative trait loci (QTL) distributed across the genome. Phenotype and DNA marker-based selection for resistance to NLB is expected to be effective. Hence, an investigation was carried out to predict the genetic value of selection candidates for resistance to NLB and compare the accuracies of genomic prediction in two F2:3 populations of two crosses (CM212 × MAI172; CM202 × SKV50) derived from contrasting parents. Linkage analysis using 297 polymorphic SNPs in population-1 and 290 polymorphic SNPs in population-2 revealed ten linkage groups spanning 3623.88cM and 4261.92cM with an average distance of 12.40cM and 14.9cM in population-1 and population-2, respectively. Location-wise and pooled data across locations identified common QTLs on linkage groups 1 and 6 in population-1 and 3 and 8 in population-2. The prediction accuracy of the QTL mapping (9.92 and 9.10 for population-1 and population-2, respectively) was based on only a few markers, which explained higher percent phenotypic variation. The prediction accuracies of the genomic estimated breeding values in the present investigation were relatively low in population-1 (0.24 to 0.26) and population-2 (0.29-0.32) compared to the expected accuracies. This could be due to fewer polymorphic markers and a small training/population size. Though the GS prediction accuracies were relatively low, they were significantly higher than QTL mapping, which promises better genetic gain per cycle. The resistant progenies from both populations were advanced to derive inbred lines and crossed with four different testers in line × tester mating design to test for their combining ability and effectiveness of genomic selection. High overall general combining ability was exhibited by 21 inbred lines. Among F1s, 48% were assigned high overall specific combining ability status. Out of the 136 single crosses, seven recorded significant positive standard heterosis over the best check for grain yield. Twenty-five inbreds with high GEBVs were crossed with four testers to obtain 100 F1s and evaluated for their response to NLB. The majority of hybrids displayed moderate to resistant reaction to NLB either in combination with susceptible or resistant testers indicating the effectiveness of selection based on high GEBVs.

First report of leaf blight of Avena strigosa caused by Pyrenophora avenicola in Japan.

Black oat (Avena strigosa Schreb.) is used as a cereal crop, forage crop or green manure in temperate regions. In Japan, it is mainly cultivated in Hokkaido island and, because of the vigorous initial growth and ability to suppress the proliferation of plant pathogenic nematodes (Uesugi et al. 2018), its use is recently increasing. In November 2021, a leaf spot and blight disease was observed in the grass cultivated in Kitahiroshima city (N43°0, E141°31). At first, blackish brown spindle-shaped or elliptical lesions, about 3 to 5 × 1 to 2 mm were formed on leaves, and they expanded by forming yellowish-brown halos around them, eventually resulting in leaf blight later on (Fig.1), damaging 5-10 % of leaf area, varied by cultivar. The lesions were excised, surface-sterilized, and incubated on water agar under near-UV light. Three single-spore isolates of Pyrenophora-like fungus were obtained from the lesions and deposited at the NIAS Genebank, Japan (https://www.gene.affrc.go.jp/index_en.php) as MAFF511692, 511693 and 511694. The sequences of ribosomal RNA gene (rDNA) and its internal transcribed spacer (ITS), and the gpd sequences of the isolates were analyzed as described by Marin-Felix et al. 2019. The rDNA-ITS sequences (GenBank accession no. LC769170, LC769171 and LC769172) of the isolates matched with that of the ex-type strain of Pyrenophora avenicola (MK539972) isolated from Avena seed. The sequences of the gpd (accession no. LC795722, LC795723 and LC795724) matched well with that of the ex-type strain (MK540180). Conidiophores of the isolates were septate, straight or flexuous, pale brown to olivaceous brown, 81.4 to 125.7 × 4.2 to 6.5 (ave. 106.4×5.7µm, n=50) µm, with hyaline vegetative hyphae (Fig.2). Conidia were slightly verrucose, cylindrical to obclavate, pale brown to olivaceous brown, 42.2 to 78.5 × 9.0 to 13.3 µm (ave. 56.9 ×10.4µm, n =50) and 2 to 7 distoseptate. This description overlap with the original description of P. avenicolai (Marin-Felix et al. 2019) and the leaf spot pathogen of Avena sativa reported in China (Chen et al. 2022). The fungus was identified as P. avenicola on the basis of morphology and molecular phylogenetic analysis. To produce inoculum, the isolate MAFF511692 was grown on V8 juice agar at 25°C under near-UV light for 7 days. Five plants each of cv. 'Soil saver', 'New oats' of A. strigosa (Kaneko seeds co.) and 'New almighty' of A. sativa (Snow brand seed co.) were grown in a greenhouse for approximately 14 days and then inoculated by atomizing them with the conidial suspension (104 conidia/ml) at the five-leaf stage. Five plants of each cultivar sprayed with sterilized distilled water served as the control. Inoculated plants were covered with plastic bags for 24 h at 25°C. After 5 days, blackish brown elliptical lesions developed on the leaves of all inoculated plants of both cultivars of A. strigosa (Fig. 3) and A. sativa, implying broad pathogenicity of the fungus to species and cultivars of Avena plants. Halo was not observed, maybe due to fewer stress in the greenhouse environment. Controls remained asymptomatic. The produced lesions were incubated as described above and the reisolated fungus was identified as P. avenicola based on the morphology, confirming Koch's postulates. To our knowledge, this is the first report of leaf blight caused by P. avenicola on black oat in Japan.

First Report of Leaf Blight on Paris polyphylla Caused by Ceratobasidium ramicola in China.

Paris polyphylla var. yunnanensisis a perennial herb with significant medicinal properties in anticancer, anti-inflammatory, antibacterial immunomodulatory and antispasmodic activities (Duan et al. 2018). In April 2022, leaf blight disease emerged in Xiangtan City (Hunan), affecting P. polyphylla plantings over an area of 3×104 m2 (27.904°N, 112.918°E). The disease incidence reached an average of 22% of the plants in the field, with infected plants initially displaying water-soaked chlorosis, followed by dry yellow shrinkage that gradually spread from the leaf tips to the entire plant. To identify the causal agent, 20 leaf lesions (4 mm2) collected from 20 plants were surface sterilized with 75% ethanol for 10 s, 5% NaOCl for 30 s, rinsed in sterile distilled water three times, transferred to potato dextrose agar (PDA) plates with lactic acid (0.125%) , and incubated at 28 °C in the dark. Four isolates (PP21 to PP24) with similar morphologies were obtained and purified by the hyphal-tip method. Colonies on PDA initially appeared white with cottony mycelium, later turning light-yellow on the underside. Septate hyphae were branched at right angles with a small constriction at the departure of the branch point and measured 4.16 to 7.93 µm in diameter. Binucleate cells within the septate hyphae were visualized using Giemsa staining (Servicebio, China). For molecular identification, the rDNA internal transcribed spacer (ITS), the second largest subunit of nuclear DNA-directed RNA polymerase II (RPB2), and ATP synthase subunit 6 (ATP6) were amplified from genomic DNA of the isolates extracted by Fungus Genomic DNA Extraction Kit (Bioflux, China) using primers ITS1/ITS4 (White et al. 1990), bRPB2-6F/bRPB2-7.1R (Matheny 2005; Reeb et al. 2004) and ATP61/ATP62 (Kretzer and Bruns 1999), respectively. The ITS, RBP2 and ATP6 of the four isolates were sequenced and deposited in GenBank. BLASTn search of sequenced ITS (PQ187050, PQ187051, PP728052, PQ187052), RBP2 (PQ202833, PQ202834, PP735921, PQ202835) and ATP6 (PQ202837, PQ202838, PP735922, PQ202839) revealed a >99% identity with the type strain of Ceratobasidium ramicola CBS133.82 (NR138368, DQ301708, and DQ301577). For phylogenetic analysis, concatenated sequences of ITS, RBP2, and ATP6 were employed using the maximum-likelihood method in MEGA-X. Based on the morphological and molecular analyses, the isolates were classified into the C. ramicola clade (Bandoni 1979; Samuels et al. 2012; Jeong et al. 2023). To test the pathogenicity of the isolate PP23, mycelial plugs (5 mm in diameter) were placed directly on 15 healthy leaves from 15 three-year-old plants after puncturing with sterile needles. Sterile PDA plugs served as controls. All plants were kept in a greenhouse with conditions of 25°C, 80% relative humidity and a photoperiod of 12 h. After 5 days, all infected plants developed leaf blight symptoms similar to those described above, whereas the control plants remained asymptomatic. The pathogenicity test was conducted three times. C. ramicolawas re-isolated from all symptomatic leaves and confirmed to be identical to the original isolate based on morphology and nucleotide sequences of ITS, RBP2, and ATP6. While C. ramicola is commonly reported to be isolated from diseased cacao, its pathogenicity to cacao remains unknown (Samuels et al. 2012). To our knowledge, this is the first report of C. ramicola causing leaf blight on P. polyphylla, a medicinal herb with significant economic importance in China.

OsGRF6-OsYUCCA1/OsWRKY82 Signaling Cascade Upgrade Grain Yield and Bacterial Blight Resistance in Rice.

As a major crop in the world, the sustainable development of rice is often severely restricted by bacterial blight. Breeding crops with resistance is an efficient way to control bacterial blight. However, enhancing resistance often incurs a fitness penalty, making it challenging to simultaneously increase bacterial blight resistance and yield potential. In this study, it is found that OsGRF6, besides being a high-yield gene, can significantly improve rice bacterial blight resistance. Compared with wild-type, the lesion lengths of transgenic material overexpressing OsGRF6 are significantly reduced after inoculation with Xanthomonas oryzae pv. oryzae (Xoo). Furthermore, OsGRF6 can directly bind to the promoters of OsYUCCA1 and OsWRKY82, upregulating their transcription and thereby increasing rice bacterial blight resistance and yield. Haplotypic analysis based on the promoter and genome sequence combined with evolutionary analysis revealed that OsGRF6 is mainly comprised by the OsGRF6XI and OsGRF6GJ subtypes. The superior haplotype OsGRF6Hap4 increased its transcriptional activity and contributed to bacterial blight resistance and rice yield. Together, this study provides theoretical support for further revealing the synergistic regulatory mechanism and genetic improvement of rice high yield and bacterial blight resistance, offering a new strategy for developing disease-resistant cultivars.

New Occurrence of Nigrospora oryzae Causing Leaf Blight in Ginkgo biloba in China and Biocontrol Screening of Endophytic Bacteria

Ginkgo biloba is a multifunctional composite tree species that has important ornamental, economic, medicinal, and scientific research value. In October 2023, the foliage of G. biloba on the campus of Nanjing Forestry University exhibited leaf blight. Black-brown necrotic spots were observed on a large number of leaves, with a disease incidence of 86%. After isolating a fungus from symptomatic leaves, pathogenicity was tested to satisfy Koch’s postulates. Using morphological features and multi-gene phylogenetic analyses of an internal transcribed spacer (ITS), elongation factor 1-alpha (EF1-α), and beta-tubulin (β-tub), the isolates YKB1-1 and YKB1-2 were identified as Nigrospora oryzae. N. oryzae was previously reported as an endophyte of G. biloba. However, this study shows it to be pathogenic to G. biloba, causing leaf spots. Two endophytic bacteria were isolated from asymptomatic leaves of diseased G. biloba trees, and their molecular identification was performed using 16S ribosomal DNA (16S rDNA). GBB1-2 was identified as Bacillus altitudinis, while GBB1-5 was identified as Bacillus amyloliquefaciens. The screening and verification of endophytic bacteria provide a new strategy for the control of N. oryzae.

Assessing genotype-by-environment interactions for maydis leaf blight disease in maize (Zea mays L.) germplasm and identification of stable donors for breeding resistant hybrid varieties

Abstract This study investigates the impact of environmental factors and genotype-by-environment interactions (GEI) on the expression of maydis leaf blight (MLB) resistance in a diverse maize germplasm comprising 359 genotypes. Extensive field trials were conducted, involving artificial inoculations and disease scoring across two locations over two years. Using genotype and genotype–environment (GGE) biplot analysis based on the site regression model (SREG), we identified stable MLB-resistant 10 donors with consistent genotypic responses. These inbred lines, which consistently exhibited disease scores of ⩽3 across locations, are recommended as potential parents for breeding MLB-resistant varieties. Furthermore, the identification of a non-crossover interaction and high correlations among testing locations allowed us to define a single mega-environment for the initial screening of MLB resistance in a large set of maize germplasm. This study suggests that initial screenings can be efficiently conducted in one representative location, with validation of resistant lines at multiple sites during advanced breeding stages. This approach optimizes the use of land, labour and resources in MLB resistance testing.

Characterization of Colletotrichum gloeosporioides and Neopestalotiopsis ellipsospora causing leaf spot and blight diseases of cinnamon in high humid tropic region of western Ghats

Characterization of Colletotrichum gloeosporioides and Neopestalotiopsis ellipsospora causing leaf spot and blight diseases of cinnamon in high humid tropic region of western Ghats

DTALE approach demonstrates that induction of common bean OVATE Family Protein 7 (PvOFP7) promotes resistance to common bacterial blight

Abstract Common bacterial blight of bean (CBB) is a devastating seed-transmitted disease caused by Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans on common bean (Phaseolus vulgaris L.). The genes responsible for CBB resistance are largely unknown. Moreover, the lack of a reproducible and universal transformation protocol limits the study of genetic traits in common bean. We produced X. phaseoli pv. phaseoli strains expressing artificially-designed Transcription-Activator Like Effectors (dTALEs) to target 14 candidate genes for resistance to CBB based on previous transcriptomic data. In planta assays in a susceptible common bean genotype showed that induction of PvOFP7, PvAP2-ERF71 or PvExpansinA17 expression by dTALEs resulted in CBB symptom reduction. After PvOFP7 induction, in planta bacterial growth was reduced at early colonisation stages and RNA-Seq analysis revealed up-regulation of cell wall formation and primary metabolism, together with major down-regulation of Heat Shock Proteins. Our results demonstrate that PvOFP7 contributes to CBB resistance, and underline the usefulness of dTALEs for functional validation of genes whose induction impacts Xanthomonas-plant interaction.

Development of a Pomegranate Fruit Disease Detection and Classification Model using Deep Learning

Background: India’s economy heavily relies on agriculture, which provides a living for a significant portion of the nation’s population. Agriculture in India faces several challenges, including fruit diseases. Pomegranate cultivation is widespread across various states in India, with Maharashtra, Karnataka Andhra Pradesh, Gujarat and Tamil Nadu being major pomegranate-producing states. Fruit disease detection and classification play a significant part in refining crop yield: water scarcity, soil degradation, outdated farming techniques and the impact of climate change. Farmer suicides are a distressing issue, often linked to financial burdens, crop failures and debt. Manual disease detection methods are labor-intensive, time-consuming and prone to errors. Furthermore, understanding the data usually requires the knowledge of qualified specialists. These restrictions may make it more difficult to detect diseases promptly and increase the chance that the disease will spread across the flock, which could have dangerous results. Methods: In this paper, we use the PomeNetV2 Convolutional Neural Network (CNN) architecture and also examine 4 diseases of pomegranate fruit with names: Alternaria, Anthracnose, Bacterial Blight, Cercospora and Healthy. We used a proposed dataset of 5099 pomegranate fruit disease images. We compared the results of the proposed pomegranate fruit disease classification method with those of existing works. Result: Based on our experimental findings, the suggested framework outperforms all other state-of-the-art models with an accuracy of 99.02% for 75 epochs in identifying healthy and diseased pomegranate fruit.