Leveillula Taurica Research Articles

A Short-Read Genome Assembly Resource for Leveillula taurica Causing Powdery Mildew Disease of Sweet Pepper (Capsicum annuum)

Powdery mildew of sweet pepper (Capsicum annuum) is an economically important disease. It is caused by Leveillula taurica, an obligate biotrophic ascomycete with a partly endophytic mycelium and haustoria, i.e., feeding structures formed in the mesophyll cells of infected host plant tissues. The molecular basis of its pathogenesis is largely unknown because genomic resources only exist for epiphytically growing powdery mildew fungi with haustoria formed exclusively in epidermal cells of their plant hosts. Here, we present the first reference genome assembly for an isolate of L. taurica isolated from sweet pepper in Hungary. The short read-based assembly consists of 23,599 contigs with a total length of 187.2 Mbp; the scaffold N50 is 13,899 kbp and N90 is 3,522 kbp; and the average GC content is 39.2%. We detected at least 92,881 transposable elements covering 55.5 Mbp (30.4%). BRAKER predicted 19,751 protein-coding gene models in this assembly. Our reference genome assembly of L. taurica is the first resource to study the molecular pathogenesis and evolution of a powdery mildew fungus with a partly endophytic lifestyle.

Diseases of Moringa and their Management

Moringa is fairly disease tolerant that is why it is relatively unaffected. However, due to changing climate, Moringa is exposed to disease infections that affect both the quantity and quality resulting to yield loss. Worldwide, there are about 12 diseases affecting moringa which are as follows: brown leaf spot (Cercospora moringicola), septoria leaf spot (Septoria lycopersici Speg.), alternaria leaf spot (Alternaria solani Sorauer), powdery mildew (Leveillula taurica Lev. Arn.), root rot (Diplodia sp.), fusarium wilt (Fusarium oxysporium f. sp. moringae), fusarium wilt (Fusarium oxysporium f. sp. moringae), fruit rot (Cochliobolus hawaiiensis Alcorn), damping off (Rhizoctonia solani Kuehn), dieback (Fusarium semitectum Berk), anthracnose (Colletotrichum chlorophyti Chandra), twig canker (Fusarium pallidoroseum Cooke Sacc.), and rust (Puccinia moringae Koorders). Proper identification of diseases on various plant parts of moringa through their symptoms, including their life cycle alternate host plants whether cultivated and non-cultivated are very important in the management of diseases.

First Report of Powdery Mildew Caused by Leveillula taurica on Capparis spinosa subsp. himalayensis from China

Capparis spinosa subsp. himalayensis (Capparaceae) as a wild plant grows widely in Xinjiang and Tibet of China, as well as northern India and Pakistan (Fici 2015; Zhang and Tucker 2008). Its root, barks, leaves, and fruits are used for the treatment of rheumatism in traditional medicine. Since 2010, C. spinosa subsp. himalayensis has been affected by a powdery mildew with nearly 80% disease incidence in the northwest of Taklimakan desert, Xinjiang, China. Symptoms of powdery mildew first appear as circular to irregular white colonies, which subsequently develop into an abundant growth on the upper and lower surface of the leaves. As the disease progresses, the infection spreads to whole leaves, resulting in leaf death and decreased medicinal value. Two representative specimens were deposited in the Mycological Herbarium of Tarim University (HMUT0911551 and HMUT0911552). Mycelium was abundantly hypophyllous, sometimes amphigenous, forming thin white patches or covering entire leaves. Conidiophores emerged through leaf stomata, singly or branched, and formed dimorphic conidia. Primary conidia were lanceolate with distinct apical points measuring 44 to 63 × 12 to 22 μm. Secondary conidia were ellipsoid to cylindrical measuring 41 to 59 × 12 to 20 μm. Both conidia were hyaline with angular/rectangular wrinkling of the outer walls. The chasmothecia were nearly gregarious and globe-shaped, 98 to 249 μm in diameter, often immersed in dense mycelial tomentum with numerous asci. Numerous and well-developed appendages on the lower half of the chasmothecia were irregularly branched. Asci were stalked, long or wide ellipsoidal in shape, and 84 to 136 × 25.4 to 56.8 μm. The asci usually contained two ellipsoidal, colorless ascospores measuring 22.8 to 46.7 × 15.4 to 28.7 μm. The specific measurements and morphological features were consistent with those of Leveillula taurica (Lev.) Arnaud (Braun and Cook 2012). To confirm the identification, the internal transcribed spacer (ITS) and 28S rDNA of isolates HMUT0911551 and HMUT0911552 were amplified and sequenced as described by Song et al. (2016). NCBI BLAST search indicated that the ITS sequences (GenBank accession nos. MG600237 and MG600238) were 99.8% (identity: 610/611) similar to L. taurica on C. spinosa and Rosa sp. from Iran (accession nos. AB045002 and AB667881) (Khodaparast et al. 2001). It also indicated that the 28S sequences (GenBank accession nos. MG600239 and MG600240) were 100% similar to L. taurica on Glancium oxylobum and Alcea sp. from Iran (accession nos. AB080474 and AB080467) (Takamatsu et al. 2008). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy potted plants. Six inoculated plants were kept under a plastic humid chamber, and three noninoculated plants served as the control. The plants were placed under greenhouse conditions at 25 to 30°C for 7 days. Typical symptoms of powdery mildew developed on the inoculated plants, with identical morphology to the original observation on diseased leaves. No symptoms were seen on the control plants. To our knowledge, this is the first report of powdery mildew caused by L. taurica on C. spinosa subsp. himalayensis. This study extends the host range of L. taurica.

<em>In vivo </em>efficacy of botanicals against powdery mildew of chilli caused by <em>Leveillula taurica </em>(Lev) Arn

<em>In vivo </em>efficacy of botanicals against powdery mildew of chilli caused by <em>Leveillula taurica </em>(Lev) Arn

Causal agents of powdery mildew on Moringa stenopetala (Baker f.) cuf. and Moringa oleifera lam. in Ethiopia

Moringa Adans. is a tropical plant genus belonging to the plant family Moringaceae, consisting of 13 species, all naturally growing and some of these cultivated in the tropics and subtropics. Species of Moringa are multipurpose trees of significant economic importance with vital nutritional, industrial, and medicinal applications. Therefore, the health of the trees is of utmost importance, but there is no methodology for its protection. The objective of the work was to investigate the spectrum of pathogens of the order Erysiphales (powdery mildews) on leaves of Moringa stenopetala (Baker f.) Cuf. and Moringa oleifera Lam. in the district (woreda) Arba Minch Zuria in Ethiopia, growing on a plantation and on native, freely growing trees in the area. Morphological examination and molecular PCR assay were used to determine powdery mildews from Moringa spp. Results show the presence of pathogen Leveillula taurica (Lév.) G. Arnaud on Moringa stenopetala on the plantation as well as on the leaves of freely growing trees. On Moringa oleifera, PCR analysis supported the presence of the pathogen Erysiphe aquilegiae DC. Additionally, the symptoms of the pathogens were described for possible control management in intensive production of Moringa plants.

Cloning of the Cytochrome b Gene From the Tomato Powdery Mildew Fungus Leveillula taurica Reveals High Levels of Allelic Variation and Heteroplasmy for the G143A Mutation.

Leveillula taurica is a major pathogen of tomato and several other crops that can cause substantial yield losses in favorable conditions for the fungus. Quinone outside inhibitor fungicides (QoIs) are routinely used for the control of the pathogen in tomato fields across California, but their recurrent use could lead to the emergence of resistance against these compounds. Here, we partially cloned the cytochrome b gene from L. taurica (Lt cytb) and searched within populations of the fungus collected from tomato fields across California for mutations that confer resistance to QoIs. A total of 21 single nucleotide polymorphisms (SNPs) were identified within a 704 bp fragment of the Lt cytb gene analyzed, of which five were non-synonymous substitutions. Among the most frequent SNPs encountered within field populations of the pathogen was the G143A substitution that confers high levels of resistance against QoIs in several fungi. The other four amino acid substitutions were novel mutations, whose effect on QoI resistance is currently unknown. Sequencing of the Lt cytb gene from individual single-cell conidia of the fungus further revealed that most SNPs, including the one leading to the G143A substitution, were present in a heteroplasmic state, indicating the co-existence of multiple mitotypes in single cells. Analysis of the field samples showed that the G143A substitution is predominantly heteroplasmic also within field populations of L. taurica in California, suggesting that QoI resistance in this fungus is likely to be quantitative rather than qualitative.

First Report of Powdery Mildew Caused by Leveillula taurica on Cucurbita ficifolia in Korea

First Report of Powdery Mildew Caused by <i>Leveillula taurica</i> on <i>Cucurbita ficifolia</i> in Korea

English

English

Distribution of powdery mildew in field and waste land weeds in urban and sub-urban areas of Central Punjab

Weeds act as alternative host of many plant pathogens as they serve source of over-wintering for a wide range of pathogens and effects on all aboveground parts of the plant. Perennials weeds play important role in the spreading of obligate pathogens. Among the prevalent diseases caused by obligate fungal pathogens, powdery mildew is counted in most common diseases especially for vegetables and ornamental plants in Pakistan. The pathogens Erysiphe cichoracearum, Sphaerotheca fuliginia, and Leveillulata urica have been reported on Convolvulus arvensis, Argemone mexicana, Rumex obtusifolious and Rumex dantatus, Euphorbia hirta, Conyza ambigua, Cucumis melo var. Agrestis and Chenopodium murale in Lahore, Faisalabad, Gujranwala and Sheikhupura districts of Central Punjab. Distribution assessment on a visual 0–5 visual rating scale was recorded at 4 severity rating on C. arvensis, while other weeds showed intermediate reaction except C. melo proved highly resistant against powdery mildew.

Identification of Resistance to Powdery Mildew in Chile Pepper

Powdery mildew [Leveillula taurica (Lév.) Arn] is a fungus causing epidemics on chile peppers (Capsicum sp.) worldwide. It was first observed in New Mexico in the late 1990s and has been a reoccurring issue. During the 2017 growing season, environmental conditions were highly favorable for powdery mildew development and severe infection was observed. This provided a unique opportunity to identify novel sources of resistance in Capsicum to powdery mildew. In the present study, the incidence and severity of powdery mildew was evaluated for 152 chile pepper accessions comprising different cultivars and species. Major differences in disease severity and incidence were observed among the accessions. Of the 152 accessions, 53 were resistant, i.e., received a disease index (DI) score of ≤1. When examining across Capsicum species, 16 Capsicum annuum accessions, all 8 Capsicum baccatum, all 21 Capsicum chinense, 5 of 6 Capsicum frutescens, the Capsicum chacoense accession, and the Capsicum rhomboideum accession were resistant. These results provide several accessions with resistance that can be used in breeding programs. Especially important are the C. annuum resistant accessions, as this resistance can be more quickly incorporated into commercially important C. annuum cultivars as compared with interspecific hybridizations.

Prevalence and severity of fungal diseases in IPM and non-IPM chilli, Capsicum annuum L fields

A field experiment was conducted at Regadaguduru village, Velugodu Mandal, Kurnool, Andhra Pradesh to study the prevalence and incidence of fungal diseases by following IPM technologies available for chilli during 2013–14. During the season powdery mildew caused by Leveillula taurica (Lev) Arn appeared in the third week of November. The incidence ranged from 15.63 to 27.39 per cent in IPM as against 18.37 to 32.32 per cent in non-IPM plots. It reached peak incidence in the first week of January (30.28%). The seasonal average of powdery mildew was 22.74 per cent in IPM as compared to 26.74 per cent in non-IPM plots. Dieback and fruit rot or anthracnose caused by Colletotrichum capsici incidence started early in the season during second week of November and reached its peak in the last week of January and declined thereafter. The incidence of dieback ranged from 9.25 to 21.45 per cent in IPM as against 11.42 to 25.23 per cent in non-IPM plots. The seasonal average incidence of dieback and fruit rot or anthracnose caused by Colletotrichum capsici was 15.20 per cent in IPM as against 18.98 per cent in non-IPM plots. The incidence of wilt/root rot ranged from 3.95 to 9.38 per cent in IPM plots as against 5.62 to 15.88 per cent in non-IPM plots. The incidence of wilt started late in the season by October and reached its peak by December. The average seasonal wilt/root rot incidence was 7.20 per cent in the IPM and 10.91 in non-IPM plots. It was noticed that the disease incidence is reduced by using location specific IPM strategies in chilli.

English

Powdery mildew disease in chilli pepper caused by Leveillula taurica has been affecting chilli pepper grown in greenhouse and open fields. Inheritance of powdery mildew disease resistance is complex and least understood. In the present study, we identified SCAR markers using F2 mapping populations developed from a cross between a resistant parental line ‘Odisha Local' and a parental line susceptible to powdery mildew ‘9907-9611'. The nucleotide sequence obtained from a genome of resistant chilli pepper line ‘Odisha Local’ using OPA15 primer showed partial identity with RPP13 like disease resistant protein. The molecular markers developed in this study will be very helpful in chilli pepper breeding programs for powdery mildew resistance for indirect selection of the resistant plants. Key words: Chilli pepper, powdery mildew, SCAR markers.

Control of powdery mildew (Leveillula taurica) using Trichoderma asperellum and Metarhizium anisopliae in different pepper types

This study investigated the effectiveness of Trichoderma asperellum (Samuels, Lieckf. & Nirenberg) and Metarhizium anisopliae (Metschn.) Sorokin in controlling pepper powdery mildew. Culture extracts of these fungi inhibited conidial germination in Leveillula taurica (Lev.) G. Arnaud. T. asperellum showed higher chitinolytic activity than that of M. anisopliae. The latter exhibited elevated β-1,3-glucanase activity as compared with that of T. asperellum. In a high-tunnel greenhouse, T. asperellum was more persistent than M. anisopliae. Jalapeno pepper was more vulnerable to powdery mildew than arbol pepper. In the field, the fungi did not control powdery mildew in jalapeno pepper. In arbol pepper, both fungal species reduced disease severity to a level similar to that of a chemical control. T. asperellum and M. anisopliae may be effective in the control of powdery mildew on peppers and could lead to the disuse of pesticides on some but not all types of pepper.

Occurrence of Powdery Mildew Caused by Golovinomyces cichoracearum sensu lato on Cannabis sativa in Canada

Cannabis sativa, a flowering plant belonging to the Cannabaceae family, increasingly is being grown in Canada for medical purposes. As of April 2018, there were 97 authorized licensed producers and more than 200,000 registered clients, making C. sativa an economically important crop in Canada (Government of Canada 2018). Symptoms of powdery mildew were observed on indoor-grown plants in production facilities in Atlantic Canada and British Columbia. Powdery mildew was present in all production sites sampled between 2013 and 2017 and ranged in incidence from 20 to 35%. Symptoms appeared as white circular patches consisting of epiphytic mycelia and conidia on the adaxial leaf surface. As the disease progressed, the mycelia, conidiophores, and conidia covered the entire surface of the leaves and spread to flower bracts and buds. The conidiophores were unbranched, cylindrical, measuring 140 to 260 µm in height, and erected singly from mycelium. Conidiophores produced between one and four conidia in chains. The conidia were hyaline, cylindrical to barrel shaped, and lacked fibrosin bodies, measuring 29 to 37 µm in length and 12 to 17 µm in width. Chasmothecia were not observed. Powdery mildew on hemp (C. sativa grown mainly for the production of seed or fiber and containing low amounts of tetrahydrocannabinol) has been previously reported to be caused by Podosphaera macularis (formerly Sphaerotheca macularis) and Leveillula taurica (McPartland 1996). To confirm the identity of the pathogen in Canada, the internal transcribed spacer (ITS) region of rDNA was amplified by polymerase chain reaction with ITS1-f and ITS4 primers and sequenced. Sequences obtained were deposited in GenBank (accession nos. MH161605 and MH161604). A GenBank BLAST search revealed 100% similarity to species belonging to Golovinomyces lineage III according to Takamatsu et al. (2013), formerly included in G. cichoracearum sensu lato. The overlapping species included G. spadiceus on Dahlia pinnata (KX821733) and G. ambrosiae on Helianthus annuus (KM657962). Voucher specimens from both species (Takamatsu et al. 2013) had 99% similarity with the cannabis isolates (G. spadiceus on Zinnia elegans [AB769425] and G. ambrosiae on Helianthus tuberosus [AB769420]). ITS sequencing is insufficient to separate G. ambrosiae and G. spadiceus (Takamatsu et al. 2013). However, G. spadiceus conidia are ≤20 µm wide, similar to our observations, whereas G. ambrosiae conidia can be wider (Braun and Cook 2012). Pathogenicity was confirmed through inoculation of four healthy C. sativa ‘Pineapple Express’ plants by pressing diseased leaves onto healthy leaves. Plants were maintained at 23 ± 2°C. Inoculated plants developed powdery mildew symptoms after 7 to 8 days, whereas uninoculated plants remained healthy. To our knowledge, this is the first report in Canada of Golovinomyces sp. on plants from the Cannabaceae family. Previous reports recognized P. macularis as causing powdery mildew on C. sativa (McPartland 1996). However, it is unclear whether this pathogen was misidentified or is a new occurrence. Recent microbiome analyses of cannabis buds revealed the presence of Golovinomyces sp. in 84% of tested samples (Thompson et al. 2017), highlighting its prevalence among licensed facilities, where powdery mildew can weaken cannabis plants, cause early leaf drop, and reduce flower bud quality.

First report of Leveillula taurica causing powdery mildew on cucumber in Mexico

First report of Leveillula taurica causing powdery mildew on cucumber in Mexico

Notes on powdery mildews (Erysiphales) in Thailand VI. Phyllactinia and Leveillula

Nine species of the genus Phyllactinia and one species of Leveillula on various hosts are recorded for Thailand. Morphological descriptions of powdery mildew specimens on hosts belonging to nine plant families and molecular phylogenetic analyses based on ITS and 28S rRNA gene sequences are provided. Phyllactinia mori-macrourae on Morus macroura (Moraceae) is proposed as new species. Phyllactinia mori-macrourae differs from Ph. moricola by having smaller chasmothecia, less chasmothecial appendages, less asci per chasmothecium, and longer ascospores. Ovulariopsis broussonetiae-papyriferae is combined to Phyllactinia broussonetiae-papyriferae. Phyllactinia alangii, Ph. dalbergiae, Phyllactinia cf. ehretiae, Ph. gmelinae, Ph. moricola, Ph. pyri-serotinae, Ph. Terminaliae, and Leveillula taurica are new records for Thailand. Ehretia laevis and S. aculeatissimum are new host records for powdery mildews species worldwide.

On mycobiota of fruit, vegetable, ornamental crops and weeds in China (results of 2017 expedition)

Samples of plants damaged with fungi were collected on the Hainan Island in vicinities of the Hainan branch of Jilin Agricultural Academy (Foluo) on 15-16.11.2017. Some samples were also collected in glasshouse farms of the Jilin Province on 12 and 16.11.2017. 40 species of fungi from Zygomycota, Ascomycota, Basidiomycota and Mitosporic fungi group are identified. Some species from Oomycota are also identified. The revealed microorganisms are registered on 36 species of plants from 36 genera, 26 families. In glasshouse farms of the Jilin Province, the most widespread and harmful diseases on vegetable cultures are false mildew of cucumber (Pseudoperonospora cubensis) and powdery mildew of pepper (Leveillula taurica), and also wilt of tomato, eggplant and pepper (Fusarium oxysporum, Verticillium dahliae). In an open ground on Hainan Island, cucumber false mildew and wilt of pepper are the most harmful. Mango leaf spot and dieback (complex of causal agents Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Botryosphaeria dothidea, Pestalotiopsis mangiferae, Phomopsis sp. and others) and papaya anthracnose (Colletotrichum gloeosporioides) have moderate severity. The collection of pure cultures of micromycetes including 106 isolates of 28 species from 27 genera of Oomycota (1), Zygomycota (2), Basidiomycota (1), Ascomycota (18) and Mitosporic fungi (84) has been created.

Molecular Mapping of PMR1, a Novel Locus Conferring Resistance to Powdery Mildew in Pepper (Capsicum annuum).

Powdery mildew, caused by Leveillula taurica, is a major fungal disease affecting greenhouse-grown pepper (Capsicum annuum). Powdery mildew resistance has a complex mode of inheritance. In the present study, we investigated a novel powdery mildew resistance locus, PMR1, using two mapping populations: 102 ‘VK515' F2:3 families (derived from a cross between resistant parental line ‘VK515R' and susceptible parental line ‘VK515S') and 80 ‘PM Singang' F2 plants (derived from the F1 ‘PM Singang' commercial hybrid). Genetic analysis of the F2:3 ‘VK515' and F2 ‘PM Singang' populations revealed a single dominant locus for inheritance of the powdery mildew resistance trait. Genetic mapping showed that the PMR1 locus is located on syntenic regions of pepper chromosome 4 in a 4-Mb region between markers CZ2_11628 and HRM4.1.6 in ‘VK515R'. Six molecular markers including one SCAR marker and five SNP markers were localized to a region 0 cM from the PMR1 locus. Two putative nucleotide-binding site leucine-rich repeat (NBS-LRR)-type disease resistance genes were identified in this PMR1 region. Genotyping-by-sequencing (GBS) and genetic mapping analysis revealed suppressed recombination in the PMR1 region, perhaps due to alien introgression. In addition, a comparison of species-specific InDel markers as well as GBS-derived SNP markers indicated that C. baccatum represents a possible source of such alien introgression of powdery mildew resistance into ‘VK515R'. The molecular markers developed in this study will be especially helpful for marker-assisted selection in pepper breeding programs for powdery mildew resistance.

First Report of Powdery Mildew Caused by Leveillula taurica on Oxalis triangularis in Korea

First Report of Powdery Mildew Caused by <i>Leveillula taurica</i> on <i>Oxalis triangularis</i> in Korea

Effects of Powdery Mildew ( Leveillula Taurica and Erysiphe Polygoni ) on Yield and Yield Components of Fenugreek in the Mid-Altitudes of Bale, South Eastern Ethiopia

Fenugreek (Trigonella foenum-graecum L.) is one of the most important seed spice crops in Ethiopia in general and in the mid-altitudes of Bale in particular. Powdery mildew caused by Leveillula taurica and Erysiphe polygoni is a common disease of fenugreek in the mid-altitudes of Bale. To determine the effects of this disease on yield and yield components of the crop, a field experiment was conducted using an improved variety, Hunda’ol, at Goro research site of Sinana Agricultural Research Center, south eastern Ethiopia. Four different spray intervals of a systemic fungicide, Lunar sensation (Fluopyram 250 g/L+ Trifloxystrobin 250 g/L), were used to create different levels of powdery mildew severity. The plots were arranged in Randomized Complete Block Design (RCBD) with three replications. There was severe powdery mildew development on plants in the unsprayed plots. The disease had significant effect on two of the yield parameters, number of seeds per pod and thousand seed weight. It inflicted the total yield loss up to 40%. Hence, application of control measure to minimize this loss is necessary. Resistant varieties are cultural tools that could be used for the management diseases of several crops. However, so far there is no powdery mildew resistant fenugreek variety released in this country. Fungicides can be used to effective control of this disease. The present study revealed that powdery mildew of fenugreek can be controlled by applying lunar sensation twice between 21-days starting from the onset of the disease.