Bipolaris Sorokiniana Research Articles

EVALUATION OF WHEAT GENOTYPES FOR SPOT BLOTCH (Bipolaris sorokiniana Sacc.) RESISTANCE AT KHAIRAHANI, CHITWAN

Wheat (Triticum aestivum L.) is the third most important cereal crop of Nepal in terms of area and production. Spot blotch caused by Bipolaris sorokiniana Sacc. is one of the major diseases reducing the productivity and quality of wheat in Nepal, which is favored by high temperature and relative humidity. The experiment was conducted at research farm of Rampur Campus, Khairahani, Chitwan from 18th Nov 2021 to 29th Mar 2022, to identify the genotypes resistance against spot blotch. It was laid out in Randomized complete block design (RCBD) with twelve genotypes as treatments and three replications. Double digit scoring method was used to assess the disease five times from 90 DAS at the interval of 7 days and Area under disease progress curve (AUDPC) was calculated. Statistically, significant difference was obtained in all the observed traits except for plant height, spike weight, harvest index, and straw yield. The highest AUDPC value was recorded in RR-21 (2074) yielding 4.0 tonha-1 whereas the lowest AUDPC value was recorded in NL 1437 (781) yielding 6.1 tonha-1, suggesting it to be more resistant than other genotypes. NL 1447 was the highest yielder (6.5tonha-1) with a 985.185 mean AUDPC value followed by NL1437 (6.1 tonha-1) while RR-21 was the lowest yielder (4.0 tonha-1). The lowest apparent infection rate was detected for BL 4951 (0.018). Correlation studies indicated that total grains and grain weight per spike as well as the grain yield were negatively and significantly correlated with AUDPC.

EVALUATION OF WHEAT GENOTYPES FOR SPOT BLOTCH (Bipolaris sorokiniana Sacc.) RESISTANCE AT KHAIRAHANI, CHITWAN

Wheat (Triticum aestivum L.) is the third most important cereal crop of Nepal in terms of area and production. Spot blotch caused by Bipolaris sorokiniana Sacc. is one of the major diseases reducing the productivity and quality of wheat in Nepal, which is favored by high temperature and relative humidity. The experiment was conducted at research farm of Rampur Campus, Khairahani, Chitwan from 18th Nov 2021 to 29th Mar 2022, to identify the genotypes resistance against spot blotch. It was laid out in Randomized complete block design (RCBD) with twelve genotypes as treatments and three replications. Double digit scoring method was used to assess the disease five times from 90 DAS at the interval of 7 days and Area under disease progress curve (AUDPC) was calculated. Statistically, significant difference was obtained in all the observed traits except for plant height, spike weight, harvest index, and straw yield. The highest AUDPC value was recorded in RR-21 (2074) yielding 4.0 tonha-1 whereas the lowest AUDPC value was recorded in NL 1437 (781) yielding 6.1 tonha-1, suggesting it to be more resistant than other genotypes. NL 1447 was the highest yielder (6.5tonha-1) with a 985.185 mean AUDPC value followed by NL1437 (6.1 tonha-1) while RR-21 was the lowest yielder (4.0 tonha-1). The lowest apparent infection rate was detected for BL 4951 (0.018). Correlation studies indicated that total grains and grain weight per spike as well as the grain yield were negatively and significantly correlated with AUDPC.

The effect of pre-sowing electron radiation on the development of barley seedlings and the activity of enzymes and phytohormones

In a laboratory experiment, the effect of pre-sowing low-energy (160 keV) electron radiation at doses of 1, 3, and 5 kGy at a dose rate of 500 Gy/pulse was studied. on sowing qualities, morphometric parameters of barley seedlings of the Vladimir spring variety, their susceptibility to fungal diseases against a natural infectious background, as well as on the activity of enzymes and the concentration of phytohormones in 7-day-old seedlings. The repetition in the experiment was 3-fold, non-irradiated seeds served as control. Irradiation of seeds at a dose of 3 kGy caused a statistically significant increase in comparison with the control of laboratory germination (LV) by 6 % and seed growth force (SPC) by 10 %, and at a dose of 1 kGy, an increase in root length by 24.6 % and had no significant effect on morphometric parameters at a dose of 5 kGy. Seed treatment did not affect the green and dry weight of the seedlings and the percentage of water content in them. Irradiation completely suppressed the development of Penicillium spp. at doses of 1, 3 and 5 kGy, Fusarium spp. - at doses of 3 and 5 kGy and significantly increased the prevalence of Bipolaris sorokiniana seedlings by 2.1 times and its prevalence by 1.8 times at a dose of 5 kGy. Electron irradiation of barley seeds had no effect on the activity of enzymes and phytohormones, except for a significant increase in 7-day-old seedlings of the content of IAA at a dose of 5 kGy by 1.5 times and IBA at a dose of 1 kGy by 2.7 times compared with the control.

A small cysteine-rich fungal effector, BsCE66 is essential for the virulence of Bipolaris sorokiniana on wheat plants

The Spot Blotch (SB) caused by hemibiotrophic fungal pathogen Bipolaris sorokiniana is one of the most devastating wheat diseases leading to 15–100% crop loss. However, the biology of Triticum-Bipolaris interactions and host immunity modulation by secreted effector proteins remain underexplored. Here, we identified a total of 692 secretory proteins including 186 predicted effectors encoded by B. sorokiniana genome. Gene Ontology categorization showed that these proteins belong to cellular, metabolic and signaling processes, and exhibit catalytic and binding activities. Further, we functionally characterized a cysteine-rich, B. sorokiniana Candidate Effector 66 (BsCE66) that was induced at 24–96 hpi during host colonization. The Δbsce66 mutant did not show vegetative growth defects or stress sensitivity compared to wild-type, but developed drastically reduced necrotic lesions upon infection in wheat plants. The loss-of-virulence phenotype was rescued upon complementing the Δbsce66 mutant with BsCE66 gene. Moreover, BsCE66 does not form homodimer and conserved cysteine residues form intra-molecular disulphide bonds. BsCE66 localizes to the host nucleus and cytosol, and triggers a strong oxidative burst and cell death in Nicotiana benthamiana. Overall, our findings demonstrate that BsCE66 is a key virulence factor that is necessary for host immunity modulation and SB disease progression. These findings would significantly improve our understanding of Triticum-Bipolaris interactions and assist in the development of SB resistant wheat varieties.

Biocontrol potential and action mechanism of Bacillus amyloliquefaciens DB2 on Bipolaris sorokiniana.

Bipolaris sorokiniana is the popular pathogenic fungi fungus which lead to common root rot and leaf spot on wheat. Generally, chemical fungicides are used to control diseases. However, the environmental pollution resulting from fungicides should not be ignored. It is important to study the mode of antagonistic action between biocontrol microbes and plant pathogens to design efficient biocontrol strategies. An antagonistic bacterium DB2 was isolated and identified as Bacillus amyloliquefaciens. The inhibition rate of cell-free culture filtrate (CF, 20%, v/v) of DB2 against B. sorokiniana reached 92.67%. Light microscopy and scanning electron microscopy (SEM) showed that the CF significantly altered the mycelial morphology of B. sorokiniana and disrupted cellular integrity. Fluorescence microscopy showed that culture filtrate destroyed mycelial cell membrane integrity, decreased the mitochondrial transmembrane potential, induced reactive oxygen species (ROS) accumulation, and nuclear damage which caused cell death in B. sorokiniana. Moreover, the strain exhibited considerable production of protease and amylase, and showed a significant siderophore and indole-3-acetic acid (IAA) production. In the detached leaves and potted plants control assay, B. amyloliquefacien DB2 had remarkable inhibition activity against B. sorokiniana and the pot control efficacy was 75.22%. Furthermore, DB2 suspension had a significant promotion for wheat seedlings growth. B. amyloliquefaciens DB2 can be taken as a potential biocontrol agent to inhibit B. sorokiniana on wheat and promote wheat growth.

Defense Inducer Compounds Up-regulated the Peroxidase, Polyphenol Oxidase, and Total Phenol Activities against Spot Blotch Disease of Wheat.

Spot blotch disease of wheat caused by Bipolaris sorokiniana (Sacc.) Shoem is considered as an economically important disease which affects all the growing stages of wheat crop. Therefore, it is important to search some effective management strategies against the spot blotch pathogen. Some synthetic elicitor compounds (salicylic acid, isonicotinic acid, and chitosan) and nano-particles (silver and aluminum) were tested against the pathogen to observe the change in biochemical activity and defense action of wheat plant against spot blotch disease. All the tested elicitor compounds and nano-particles showed a significant increase in activity of peroxidase, polyphenol oxidase (PPO), and total phenol over control. The highest increase in activity of peroxidase was recorded at 72 h from chitosan at 2 mM and 96 h from silver nano-particle at 100 ppm. Maximum PPO and total phenol activity were recorded from chitosan at 2 mM and silver nano-particle at 100 ppm as compared to pathogen-treated and healthy control. The lowest percent disease index, lowest no. of spots/leaf, and no. of infected leaves/plant were found in silver nano-particle at 100 ppm and chitosan at 2 mM, respectively. The use of defense inducer compounds results in significantly up-regulated enzymatic activity and reduced spot blotch disease. Therefore, chitosan and silver nano-particle could be used as alternative methods for the management of spot blotch disease.

Genetics and breeding for resistance against four leaf spot diseases in wheat (Triticum aestivum L.).

In wheat, major yield losses are caused by a variety of diseases including rusts, spike diseases, leaf spot and root diseases. The genetics of resistance against all these diseases have been studied in great detail and utilized for breeding resistant cultivars. The resistance against leaf spot diseases caused by each individual necrotroph/hemi-biotroph involves a complex system involving resistance (R) genes, sensitivity (S) genes, small secreted protein (SSP) genes and quantitative resistance loci (QRLs). This review deals with resistance for the following four-leaf spot diseases: (i) Septoria nodorum blotch (SNB) caused by Parastagonospora nodorum; (ii) Tan spot (TS) caused by Pyrenophora tritici-repentis; (iii) Spot blotch (SB) caused by Bipolaris sorokiniana and (iv) Septoria tritici blotch (STB) caused by Zymoseptoria tritici.

Spot blotch disease resistance and heat stress tolerance in spring wheat (Triticum aestivum L.)

Spot blotch caused by Bipolaris sorokiniana is a major disease of wheat in warm and humid regions of Nepal. The fungus has a worldwide distribution but as a pathogen, it is the most aggressive under the conditions of high relative humidity and temperature associated with the low fertility of soils in Nepal. The yield loss due to the disease is very significant in Nepal. This experiment was conducted to identify the genotypes having a good level of resistance against spot blotch. Canopy temperature measurements using infrared thermometry, to assess variation in foliar blight resistance along with heat tolerance as an integrative selection criterion. The experiment set was comprising 52 genotypes and arranged in alpha lattice design with two replications in 2017/-2018 Directorate of agricultural research center, Parwanipur, Bara, Nepal. Each plot size was 8 rows of 3 meters long. Three times disease scoring was done in Flag leaf, and Penultimate leaf method and calculated the Area under the disease progress curve (AUDPC). Other data were analyzed by using R software (4.2.2). Canopy temperature, heading days, days to maturity, plant height, number of grains per spike (NGPS), number of tillers per meter square (NTPM), thousand-grain weight (TGW), and grain yield were found highly significant. The genotype 32 was found the highest yielder (5141 kg/ha) and canopy temperature 16.50 C with a 279; 610 F; F-1AUDPC, respectively.

Synthesis and Evaluation on the Fungicidal Activity of S-Alkyl Substituted Thioglycolurils

A series of S-alkyl substituted thioglycolurils was prepared through the alkylation of corresponding thioglycolurils with halogenoalkanes and tested for their fungicidal activity against six phytopathogenic fungi from different taxonomic classes: Venturia inaequalis, Rhizoctonia solani, Fusarium oxysporum, Fusarium moniliforme, Bipolaris sorokiniana, and Sclerotinia sclerotiorum, and two pathogenic yeasts: Candida albicans and Cryptococcus neoformans var. grubii. A number of S-alkyl substituted thioglycolurils exhibited high activity against Venturia inaequalis and Rhizoctonia solani (85-100% mycelium growth inhibition), and moderate activity against other phytopathogens. S-Ethyl substituted thioglycolurils possessed a high activity against Candida albicans. Additionally, the hemolytic and cytotoxic properties of promising derivatives were determined using human red blood cells and human embryonic kidney cells, respectively. Two S-ethyl derivatives possessed both low cytotoxicity against normal human cells and high fungicidal activity against Candida albicans.

Functional characterization of N-acetyl glucosaminidase from Myrothecium verrucaria for bio-control of plant pathogenic fungi and bio-production of N-acetyl glucosamine

As a common structural element of invertebrates and fungi, chitin offers an ideal target for bio-control of agricultural pests as well as production of N-acetyl glucosamine (NAG). Therefore, chitin degrading enzymes have several biotechnological applications. In the present investigation, the bio-control and NAG production potential of Myrothecium verrucaria N-acetyl glucosaminidase (MvNAGase) were studied. Cloning and biochemical characterization of MvNAGase (1743 bp) suggest that it belongs to the glycosyl hydrolase-20 family. Chitooligosaccharides hydrolysis revealed the exo-acting nature of the enzyme with NAG as an end product. rMvNAGase displayed significant antifungal potential towards plant pathogenic fungi: Ustilago maydis, Bipolaris sorokiniana and Fusarium oxysporum. The bioprocess was optimized using an enzymic cocktail of earlier identified and characterized endo-chitinase and rMvNAGase to maximize NAG production from the chitin. Under specific experimental conditions, the chitin conversion was achieved up to 87%. The study propose the possible application of rMvNAGase in bio-control of agricultural pests and biochemical production of NAG from the crude chitin.

Whole-genome sequencing-based characterization of Streptomyces sp. 6(4): focus on natural product.

We have sequenced the whole genome of Streptomyces sp. 6(4) isolated from tomato roots that presents antifungal activity against phytopathogenic fungi, mainly Bipolaris sorokiniana. The genome has almost 7 Mb and 3368 hypothetical proteins that were analysed and characterized in Uniprot with the emphasis on biological compounds. Multilocus sequence typing (MLST) analyses were performed in an effort to characterize and identify this isolate, resulting in a new sequence type (ST), classified as ST64. Phenetic and phylogenetic trees were constructed to investigate Streptomyces sp. 6(4) evolution and sequence similarity, and the isolate is a strain closer to Streptomyces prasinus and Streptomyces viridosporus . It is known that the genus Streptomyces possess huge metabolic capacity with the presence of cryptic genes. These genes are usually present in clusters, which are responsible for the production of diverse natural products, mainly antibiotics. In addition, 6(4) showed 11 biosynthetic gene clusters through antiSMASH, including 3 polyketide synthase (PKS) and non-ribosomal peptide synthase (NRPS) type clusters.

First Report of Brown Leaf Spot of Elymus nutans Caused by Bipolaris sorokiniana in Northwestern China.

Elymus nutans is an important feed and forage resource in alpine region of northwestern China, and helps to maintain the ecological balance on Qinghai-Tibetan plateau (Fei et al. 2010). In September 2021, brown leaf spots were observed in Shandan Horse Farm (38.3061°N, 101.2453°E), Gansu province of China.Disease severity of leaves was estimated to be 38% based on a random sample of 100 leaves from each of 10 arbitrarily placed quadrats on the farm.The typical symptoms on leaves appeared as brown to dark brown spots with grayish white in the center, surrounded by a yellow halo. A total of twenty diseased leaves were collected from five different plants in the field. The lesions (about 5 mm) from these samples were initially soaked in 75% ethanol for 30 s followed by soaking in 1% NaClO solution for 1 min, repeatedly rinsed with sterilized water, air dried, and put on potato dextrose agar (PDA). After 7 days of incubation at 25°C in the dark, the same fungus was consistently isolated; the pure isolates were obtained by single-spore cultures (Cai et al. 2009). The colonies were irregular in shape and black in color with white margins. Conidia were spindle-shaped, dark brown, 5 to 9 septa (7 septa in general), and a size range of 21.74 to 78.97 × 7.95 to 21.12 µm (avg. 57.25 × 17.76 µm, n = 50),morphologically similar to B. sorokiniana reported on Avena nuda in China (Li et al. 2019). The ITS region of rDNA and partial glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene of the representative isolate PJC5 were amplified using the primers ITS1/ITS4 and gpd1/gpd2, respectively (Manamgoda et al. 2014). After sequencing sequences were deposited into GenBank with accession numbers OM419194 (ITS) and OM718009 (GAPDH). BLAST analysis showed 99% and 100% identity with the corresponding sequences (accession numbers MH855159.1 and HG779088.1) of known strain CBS 140.31 of B. sorokiniana (Manamgoda et al. 2014). For pathogenicity tests, ten 8-week-old healthy plants obtained by growing E. nutans in pots were spray-inoculated separately with a conidia suspension of 1 × 106 conidia/ml of isolate PJC5. Ten plants were also sprayed with sterilized distilled water as controls. Then all plants were individually covered with transparent polyethylene bags for three days to maintain high relative humidity and placed in greenhouse at 25°C. Seven days after inoculation, symptoms of leaf infection were similar to those observed in the field, while no symptoms appeared on leaves of control plants. The experiments were conducted three times and the pathogen was re-isolated from inoculated leaves and was confirmed as B. sorokiniana based on morphological and molecular analyses.B. sorokiniana has been reported to cause leaf spot of E. riparius in the United States (Roane et al. 2005) and E. breviaristatus (Zhuang, 2005) and A. nuda (Li et al. 2019) in China. To our knowledge, this is thefirstreportofB.sorokinianacausing leaf spot onE. nutansin China. Identifying this pathogen provides a foundation to prevent this complex disease and to reduce economic loss.

Managing spot blotch disease in wheat: Conventional to molecular aspects.

Spot blotch (SB) caused by Bipolaris sorokiniana (teleomorph Cochliobolus sativus) is one of the devastating diseases of wheat in the warm and humid growing areas around the world. B. sorokiniana can infect leaves, stem, roots, rachis and seeds, and is able to produce toxins like helminthosporol and sorokinianin. No wheat variety is immune to SB; hence, an integrated disease management strategy is indispensable in disease prone areas. A range of fungicides, especially the triazole group, have shown good effects in reducing the disease, and crop-rotation, tillage and early sowing are among the favorable cultural management methods. Resistance is mostly quantitative, being governed by QTLs with minor effects, mapped on all the wheat chromosomes. Only four QTLs with major effects have been designated as Sb1 through Sb4. Despite, marker assisted breeding for SB resistance in wheat is scarce. Better understanding of wheat genome assemblies, functional genomics and cloning of resistance genes will further accelerate breeding for SB resistance in wheat.

Comparative Studies on Synthesis, Characterization and Photocatalytic Activity of Ag Doped ZnO Nanoparticles.

In this work, silver (Ag) doped zinc oxide (ZnO) nanoparticles were synthesized using zinc chloride, zinc nitrate, and zinc acetate precursors with (0 to 10) wt % Ag doping by a simple reflux chemical method. The nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet visible spectroscopy, and photoluminescence spectroscopy. The nanoparticles are studied as a photocatalyst for visible light driven annihilation of methylene blue and rose bengal dyes. The 5 wt % Ag doped ZnO displayed optimum photocatalytic activity toward methylene blue and rose bengal dye degradation at the rate of 13 × 10-2 min-1 and 10 × 10-2 min-1, respectively. Here we report antifungal activity for the first time using Ag doped ZnO nanoparticles against Bipolaris sorokiniana, displaying 45% efficiency for 7 wt % Ag doped ZnO.

Antagonistic Strain Bacillus halotolerans Jk-25 Mediates the Biocontrol of Wheat Common Root Rot Caused by Bipolaris sorokiniana

Common root rot caused by Bipolaris sorokiniana infestation in wheat is one of the main reasons for yield reduction in wheat crops worldwide. The bacterium strain JK-25 used in the current investigation was isolated from wheat rhizosphere soil and was later identified as Bacillus halotolerans based on its morphological, physiological, biochemical, and molecular properties. The strain showed significant antagonism to B. sorokiniana, Fusarium oxysporum, Fusarium graminearum, and Rhizoctonia zeae. Inhibition of B. sorokiniana mycelial dry weight and spore germination rate by JK-25 fermentation supernatant reached 60% and 88%, respectively. The crude extract of JK-25 was found, by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), to contain the surfactin that exerted an inhibitory effect on B. sorokiniana. The disruption of mycelial cell membranes was observed under laser scanning confocal microscope (LSCM) after treatment of B. sorokiniana mycelium with the crude extract. The antioxidant enzyme activity of B. sorokiniana was significantly reduced and the oxidation product malondialdehyde (MDA) content increased after treatment with the crude extract. The incidence of root rot was significantly reduced in pot experiments with the addition of JK-25 culture fermentation supernatant, which had a significant biological control effect of 72.06%. Its ability to produce siderophores may help to promote wheat growth and the production of proteases and pectinases may also be part of the strain's role in suppressing pathogens. These results demonstrate the excellent antagonistic effect of JK-25 against B. sorokiniana and suggest that this strain has great potential as a resource for biological control of wheat root rot strains.

Feature of the photosynthetic pigment fund in seedlings of different varieties of spring barley when affected by the fungus <i>Bipolaris sorokiniana</i> (Sacc.) Shoem

The objects of research were the first leaves of green seedlings of spring barley (Hordeum vulgare L.) of the varieties of Belarusian breeding − filmy (Magutny, Raider) and naked (Adamant). Seedlings of different age (3, 5, and 10 days old) were infected with spores of the fungus Bipolaris sorokiniana (Sacc.) Shoem. − a causative agent of helminthosporiasis, and were analyzed 2 days after infection. Varietal and ontogenetic differences between barley cultivars in morphological parameters of the first leaves, the content of photosynthetic pigments (chlorophylls (Chl) and carotenoids), and the ratio of spectral forms of Chl at the seedling stage were found. Different amplitudes of changes in the photosynthetic pigment content between the barley varieties with helminthosporiasis at different stages of development of the first leaf were established.

Detection of seed-borne fungal pathogens associated with wheat (Triticum aestivum L.) seeds collected from farmer fields and grain market

BackgroundThe plant pathogens significantly affect quality and marketability of several cereal crops. Of these, seed-borne phytopathogens are responsible for quality and quantity losses in crops on commercial scale. The aim of this study was to isolate and detect the seed-borne mycoflora from seed lots of various bread wheat (Triticum aestivum L.) genotypes widely grown in Bahawalpur division of south Punjab, Pakistan. MethodsEleven commercial wheat cultivars/genotypes were investigated through standard blotter paper method. The samples were randomly collected from farmer fields and grain markets. The collected samples were brought to the laboratory and analyzed with different methods to detect the mycoflora. ResultsTwenty-one fungal species were recovered from seeds lots of diversified gene pool. The most frequently isolated fungi were Alternaria alternata, Fusarium monoliformae, Aspergillus flavus, Helminthosporium spp., Curvularia spp., Bipolaris sorokiniana, Phoma spp. and Penicillium spp. The one devasting fungal specie Alternaria alternata (88.8%) was the dominating species in all wheat genotypes included in the study. ConclusionThese results divulge the presence of fungal pathogens in all wheat cultivars and could exert adverse effect on their allometric traits. So, there is a potential need to control these seed borne pathogens to minimize the crop yield losses.

Quantitative trait loci for resistance to black point caused by Bipolaris sorokiniana in bread wheat.

The online version contains supplementary material available at 10.1007/s11032-023-01356-6.

Development of Diagnostic Markers and Applied for Genetic Diversity Study and Population Structure of Bipolaris sorokiniana Associated with Leaf Blight Complex of Wheat

Bipolaris sorokiniana, a key pathogenic fungus in the wheat leaf blight complex, was the subject of research that resulted in the development of fifty-five polymorphic microsatellite markers. These markers were then used to examine genetic diversity and population structure in Indian geographical regions. The simple sequence repeat (SSR) like trinucleotides, dinucleotides, and tetranucleotides accounted for 43.37% (1256), 23.86% (691), and 16.54% (479) of the 2896 microsatellite repeats, respectively. There were 109 alleles produced by these loci overall, averaging 2.36 alleles per microsatellite marker. The average polymorphism information content value was 0.3451, with values ranging from 0.1319 to 0.5932. The loci's Shannon diversity varied from 0.2712 to 1.2415. These 36 isolates were divided into two main groups using population structure analysis and unweighted neighbour joining. The groupings were not based on where the isolates came from geographically. Only 7% of the overall variation was found to be between populations, according to an analysis of molecular variance. The high amount of gene flow estimate (NM = 3.261 per generation) among populations demonstrated low genetic differentiation in the entire populations (FST = 0.071). The findings indicate that genetic diversity is often minimal. In order to examine the genetic diversity and population structure of the B. sorokiniana populations, the recently produced microsatellite markers will be helpful. This study's findings may serve as a foundation for developing improved management plans for the leaf blight complex and spot blotch of wheat diseases in India.

Fungal Pathogens Associated with Crown and Root Rot in Wheat-Growing Areas of Northern Kyrgyzstan.

Fungal species associated with crown and root rot diseases in wheat have been extensively studied in many parts of the world. However, no reports on the relative importance and distribution of pathogens associated with wheat crown and root rot in Kyrgyzstan have been published. Hence, fungal species associated with wheat crown/root rot were surveyed in three main wheat production regions in northern Kyrgyzstan. Fungal species were isolated on 1/5 strength potato-dextrose agar amended with streptomycin (0.1 g/L) and chloramphenicol (0.05 g/L). A total of 598 fungal isolates from symptomatic tissues were identified using morphological features of the cultures and conidia, as well as sequence analysis of the nuclear ribosomal internal transcribed spacer (ITS) region, the translation elongation factor 1α (TEF1), and the RNA polymerase II beta subunit (RPB2) genes. The percentage of fields from which each fungus was isolated and their relative percentage isolation levels were determined. Bipolaris sorokiniana, the causal agent of common root rot, was the most prevalent pathogenic species isolated, being isolated from 86.67% of the fields surveyed at a frequency of isolation of 40.64%. Fusarium spp. accounted for 53.01% of all isolates and consisted of 12 different species. The most common Fusarium species identified was Fusarium acuminatum, which was isolated from 70% of the sites surveyed with an isolation frequency of 21.57%, followed by Fusarium culmorum, Fusarium nygamai, Fusarium oxysporum, and Fusarium equiseti, all of which had a field incidence of more than 23%. Inoculation tests with 44 isolates representing 17 species on the susceptible Triticum aestivum cv. Seri 82 revealed that Fusarium pseudograminearum and F. culmorum isolates were equally the most virulent pathogens. The widespread distribution of moderately virulent B. sorokiniana appears to be a serious threat to wheat culture, limiting yield and quality. With the exception of F. culmorum, the remaining Fusarium species did not pose a significant threat to wheat production in the surveyed areas because common species, such as F. acuminatum, F. nygamai, F. oxysporum, and F. equiseti, were non-pathogenic but infrequent species, such as Fusarium redolens, Fusarium algeriense, and F. pseudograminearum, were highly or moderately virulent. Curvularia inaequalis, which was found in three different fields, was mildly virulent. The remaining Fusarium species, Fusarium solani, Fusarium proliferatum, Fusarium burgessii, and Fusarium tricinctum, as well as Microdochium bolleyi, Microdochium nivale, and Macrophomina phaseolina, were non-pathogenic and considered to be secondary colonizers. The implications of these findings are discussed.