Spot Blotch Of Wheat Research Articles

Utilization of Stenotrophomonas koreensis and Bacillus amyloliquefaciens for Improving Growth, Reducing Nitrogen Fertilization and Controlling Bipolaris sorokiniana in Wheat

Wheat (<em>Triticum aestivum</em> L.), a vital cereal, faces significant challenges from common root rot and spot blotch diseases caused by <em>Bipolaris sorokiniana</em>. This study aimed to explore the potential of plant growth promoting rhizobacteria (PGPR) to enhance wheat growth, reduce fertilizer input, and combat <em>Bipolaris </em>diseases. Two PGPR isolates, selected for their superior antagonistic properties, were identified as <em>Stenotrophomonas koreensis</em> RB11 and <em>Bacillus amyloliquefaciens </em>RB12. These PGPR strains displayed multiple plant growth promoting and biocontrol attributes, including phosphate solubilization, indole-3-acetic acid production, nitrogen fixation and antagonism against <em>B. sorokiniana</em> and other fungi. Wheat seed priming with the PGPR significantly improved germination, plant growth, nutrient content and biomass carbon accumulation in the rhizosphere soil. Importantly, the application of RB11 and RB12 allowed for a 25% and 50% reduction in nitrogen fertilizer usage, respectively, without compromising the yield. RB11 and RB12 also demonstrated potent inhibitory effects on <em>B. sorokiniana</em> conidial germination and significantly controlled common root rot and spot blotch in wheat, similar to those observed with the fungicide Protaf 250EC. Overall, this study underscores the multifaceted roles of <em>S. koreensis</em> RB11 and <em>B. amyloliquefaciens</em> RB12 in promoting wheat growth, reducing fertilizer inputs and effectively suppressing wheat pathogens. These findings contribute to the development of PGPR-based strategies for sustainable crop production and disease control.

Effect of total phenolic content (TPC) and activity of phenylalanine ammonia-lyase (PAL) on spot blotch of wheat incited by Bipolaris sorokiniana

Effect of total phenolic content (TPC) and activity of phenylalanine ammonia-lyase (PAL) on spot blotch of wheat incited by Bipolaris sorokiniana

Inhibitory Effect of Nano-Fungicides and Fungicides on Radial Mycelial Growth of Bipolaris sorokiniana Causing Spot Blotch of Wheat under in vitro Condition

Bipolaris sorokiniana (Sacc.) Shoem, causing spot blotch of wheat is most important disease of wheat in north eastern plains zone (NEPZ) representing warm and humid climate in India as well as in other South Asian countries. The disease is known to cause yield losses up to 50% as well as deterioration in seed quality. The present study is carried out to check inhibitory effect of nanofungicides and fungicides against Bipolaris sorokiniana. Among nanofungicides, silver nanofungicide at 100 ppm was found highly effective and inhibit the growth by 86.10% followed by agritec nanofungicide (81.41%) and selenium nanofungicide (77.01%). Among fungicides, maximum inhibition (82.57%) was observed in propiconazole at 0.2% followed by hexaconazole (78.96%) and folicure (75.92%) under in vitro condition.

Native rhizobacteria suppresses spot blotch disease, improves growth and yield of wheat under salt–affected soils

The simultaneous occurrence of biotic and abiotic stresses affects the performance of the crops in salt–affected agroecologies. The plant–microbe interaction with effective rhizobacteria can effectively manage these stresses. This study characterized the biocontrol, plant growth promotion, and responsiveness of rhizobacteria in wheat under salt-affected soils. Out of the 184 rhizobacteria isolates, the 20 isolates showed 41–72% growth inhibition of fungal phytopathogens of seedling blight of wheat (Fusarium sp), head blight of wheat (Fusarium oxysporum), onion molds (Penicillium sp and Aspergillus sp), root rot of wheat (Rhizoctonia solani), ear rot of corn (Aspergillus sp.) and spot blotch of wheat (Bipolaris sorokininana). The potent three rhizobacterial isolates identified as close neighbours of Bacillus amyloliquefaciens strain TA124, B. subtilis strain SB67 and B. subtilis strain BJ171 caused 65.5–71.1% growth inhibition of B. sorokiniana. The extracellular organic acid, siderophore, and chitinase enzymes played a significant role in rhizobacterial performance for fungal growth inhibition; and P and Zn solubilization in growth media. The foliar spray of bioformulation aids 15–20% reduction in the B. sorokiniana disease severity. The rhizobacterial responsiveness to the dual inoculation through seed treatment and foliar spray was 12.6–51, 15.8–46.3, and 13.2–148.1% for grain yield, P uptake, and disease suppression, respectively. The changes caused by rhizobacterial bioformulation in soil (Olsen's–P and microbial biomass carbon) and plant (proline, malondialdehyde, peroxidase, and Na+/K+ratio) explained 85% variability in the yield, P nutrition, and disease severity. Therefore, native rhizobacteria with biocontrol and plant growth-promoting capabilities can be an effective option for managing multiple stresses of crops in salt–affected agroecologies.

A rapid detached leaf assay for the phenotyping of spot blotch of wheat

A rapid detached leaf assay for the phenotyping of spot blotch of wheat

Targeting Disease Susceptibility Genes in Wheat Through wide Hybridization with Maize Expressing Cas9 and Guide RNA.

Two genes (TaHRC and Tsn1) conferring susceptibility to Fusarium head blight and tan spot, Septoria nodorum blotch, and spot blotch in wheat were targeted through wide hybridization with maize expressing Cas9 and guide RNA (gRNA). For each gene, two target sites were selected and corresponding gRNA expression cassettes were synthesized and cloned into a binary vector carrying the CRISPR/Cas9-mediated genome editing machinery. The constructed binary vectors were used to transform the hybrid maize Hi-II through an Agrobacterium-mediated approach to generate T0 and T1 plants, which were used to cross with wheat variety Dayn for targeting Tsn1 or the susceptible allele (TaHRC-S) of TaHRC as well as with the near-isogenic line (Day-Fhb1) of Dayn for targeting the resistant allele (TaHRC-R) of TaHRC. Haploid embryos were rescued in vitro from the wide crosses to generate haploid plants. PCR amplification and sequencing indicated that 15 to 33% of the haploid plants contained the target gene with mutations at the target sites. This wheat × maize hybridization combined with genome editing approach provides a useful alternative tool, not only for targeting susceptibility genes to improve disease resistance without regulatory issues, but also for understanding gene function in wheat. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Genetics of spot blotch resistance in bread wheat (Triticum aestivum L.) using five models for GWAS.

Genetic architecture of resistance to spot blotch in wheat was examined using a Genome-Wide Association Study (GWAS) involving an association panel comprising 303 diverse genotypes. The association panel was evaluated at two different locations in India including Banaras Hindu University (BHU), Varanasi (Uttar Pradesh), and Borlaug Institute for South Asia (BISA), Pusa, Samastipur (Bihar) for two consecutive years (2017-2018 and 2018-2019), thus making four environments (E1, BHU 2017-18; E2, BHU 2018-19; E3, PUSA, 2017-18; E4, PUSA, 2018-19). The panel was genotyped for 12,196 SNPs based on DArT-seq (outsourced to DArT Ltd by CIMMYT); these SNPs included 5,400 SNPs, which could not be assigned to individual chromosomes and were therefore, described as unassigned by the vendor. Phenotypic data was recorded on the following three disease-related traits: (i) Area Under Disease Progress Curve (AUDPC), (ii) Incubation Period (IP), and (iii) Lesion Number (LN). GWAS was conducted using each of five different models, which included two single-locus models (CMLM and SUPER) and three multi-locus models (MLMM, FarmCPU, and BLINK). This exercise gave 306 MTAs, but only 89 MTAs (33 for AUDPC, 30 for IP and 26 for LN) including a solitary MTA detected using all the five models and 88 identified using four of the five models (barring SUPER) were considered to be important. These were used for further analysis, which included identification of candidate genes (CGs) and their annotation. A majority of these MTAs were novel. Only 70 of the 89 MTAs were assigned to individual chromosomes; the remaining 19 MTAs belonged to unassigned SNPs, for which chromosomes were not known. Seven MTAs were selected on the basis of minimum P value, number of models, number of environments and location on chromosomes with respect to QTLs reported earlier. These 7 MTAs, which included five main effect MTAs and two for epistatic interactions, were considered to be important for marker-assisted selection (MAS). The present study thus improved our understanding of the genetics of resistance against spot blotch in wheat and provided seven MTAs, which may be used for MAS after due validation.

In vivo and in vitro assessment of plant extracts against the Bipolaris sorokiniana disease causing spot blotch of wheat

In vivo and in vitro assessment of plant extracts against the Bipolaris sorokiniana disease causing spot blotch of wheat

Whole Genome Sequencing and Comparative Genomics of Indian Isolates of Wheat Spot Blotch Pathogen Bipolaris sorokiniana Reveals Expansion of Pathogenicity Gene Clusters.

Spot blotch is a highly destructive disease in wheat caused by the fungal pathogen Bipolaris sorokiniana (teleomorph, Cochliobolus sativus). It is prevalent in warm and humid areas, including Africa, Asia, Latin America, and the USA. In the present study, twelve isolates of B. sorokiniana were collected from wheat fields in three different geographical locations in India. The pathogenicity of seven sporulating isolates was assessed on 'DDK 1025', a spot blotch-susceptible wheat variety under greenhouse conditions. The isolate 'D2' illustrated the highest virulence, followed by 'SI' and 'BS52'. These three isolates were sequenced using the Illumina HiSeq1000 platform. The estimated genome sizes of the isolates BS52, D2, and SI were 35.19 MB, 39.32 MB, and 32.76 MB, with GC contents of 48.48%, 50.43%, and 49.42%, respectively. The numbers of pathogenicity genes identified in BS52, D2, and SI isolates were 2015, 2476, and 2018, respectively. Notably, the isolate D2 exhibited a relatively larger genome with expanded arsenals of Biosynthetic Gene Clusters (BGCs), CAZymes, secretome, and pathogenicity genes, which could have contributed to its higher virulence among the tested isolates. This study provides the first comparative genome analysis of the Indian isolates of B. sorokiniana using whole genome sequencing.

Trichoderma harzianum sensu lato TSM39: A wheat microbiome fungus that mitigates spot blotch disease of wheat (Triticum turgidum L. subsp. durum) caused by Bipolaris sorokiniana

Bipolaris sorokiniana - the causal agent of wheat spot blotch - is an emerging phytopathogenic fungus in the Yaqui Valley, Sonora, Mexico. At present, its control relies on the use of harmful chemicals, partly due to the lack of effective alternatives. Thus, this work aimed to identify and characterize indigenous wheat-associated fungal strains with biocontrol capacity against B. sorokiniana that can be integrated into control strategies for spot blotch management. Out of 59 fungal strains evaluated, we identified 5 strains with antagonistic activity against B. sorokiniana by dual confrontation assay, and these were taxonomically assigned as Trichoderma harzianum sensu lato (strains TSM39 and TSO39), Aspergillus terreus (strains TRQ89 and TRQ93), and Aspergillus nidulans (strain TRQ83) based on phylogenetic analysis using the ITS region of the rRNA cistron. Trichoderma harzianum TSM39 showed interesting biological control traits (i.e., strong antagonistic activity, high growth rate, non-cytotoxicity) and its application to wheat plants - under highly conducive conditions for spot blotch outbreak- resulted in a significant reduction of disease severity. In vitro experiments revealed that the chitinolytic system of strain TSM39 responds to B. sorokiniana lysates (signals), which could have potential biotechnological applications to improve its biocontrol activity. Additionally, a solid-state fermentation system was successfully established for spore production of strain TSM39. Taken together, Trichoderma harzianum sensu lato TSM39 is a biocontrol agent against B. sorokiniana with the potential to be integrated into spot blotch management strategies and contribute to the sustainability of the region.

Molecular diversity, haplotype distribution and genetic variation flow of Bipolaris sorokiniana fungus causing spot blotch disease in different wheat-growing zones.

Bipolaris sorokiniana (BS) is an economically important fungal pathogen causing spot blotch of wheat (Trtiticum aestivum) and found in all wheat-growing zones of India. Very scanty and fragmentary information is available on its genetic diversity. The current research is the first detailed report on the geographic distribution and evolution of BS population in five geographically distinct wheat-growing zones (North Western Plain Zone (NWPZ), North Eastern Plain zone (NEPZ), North Hill Zone (NHZ), Southern Hill Zone (SHZ) and Peninsular Zone (PZ)) of India, studied by performing nucleotide sequence comparison of internal transcribed spacer region of 528 isolates. A moderate to low levels of haplotypic diversity was noticed in different wheat-growing zones. Phylogenetic analysis suggests that B. sorokiniana exist in two distinct lineages as all isolates under study were grouped in two different clades and found analogous to the findings of haplotypic and TCS network analysis. The genetic parameters revealed the existence of 40 haplotypes with three major haplotypes (H-1, H-2 and H-3) which showed star-like structure network surrounded by several single haplotypes, revealing high frequency of the mutations (Eta = 2 - 158) in total analyzed population. H-1 was observed as a predominant haplotype and prevalent in all the five zones. Moderate level of genetic differentiation was found between NHZ and other zones like NWPZ (Fst = 0.332) and SHZ (Fst = 0.382) and PZ (Fst = 0.299), whereas it was low between NEPZ and PZ (Fst = 0.034). Higher transfer rate of genetic variation was noticed between NEPZ and PZ (Nm = 7.06), while it was found minimum between NHZ and SHZ (Nm = 0.40). Moreover, negative score of neutrality statistics (Tajima's D and Fu's FS test) for NWPZ population suggested recent population expansion. However, positive score for both the neutrality tests observed in NEPZ indicated the dominance of balancing selection in structuring their population. Recombination events were observed in the NWPZ and NHZ population, while it was absent in SHZ, NEPZ and PZ population. Thus, the lack of any specific genetic population structure in all the zones indicates for the expansion history only from one common source population, i.e. NWPZ, a mega zone of wheat production in India. Overall, it seems that the predominance of individual haplotypes with a moderate level of genetic variation and human-mediated movement of contaminated seed and dispersal of inoculum, mutations and recombination as prime evolutionary processes play essential role in defining the genetic structure of BS population.

Evaluation of differentially expressed genic marker linked resistance gene analog (RGAs) effective at seedling stage against spot blotch in wheat

Evaluation of differentially expressed genic marker linked resistance gene analog (RGAs) effective at seedling stage against spot blotch in wheat

Development of an economically viable and effective fungicide spray schedule for the management of spot blotch of wheat

Development of an economically viable and effective fungicide spray schedule for the management of spot blotch of wheat

Potential biocontrol mechanisms of Bacillus sp. TSO2 against Bipolaris sorokiniana, spot blotch in wheat

<p class="Default"><em>Bipolaris sorokiniana </em>is a pathogen of cereals such as wheat and barley, causing root rot, leaf blight, seedling blight, and spot blotch. This phytopathogen causes a considerable reduction in cereal yield of up to 85%. Thus, sustainable alternatives to the application of synthetic fungicides are determinants for the control of phytopathogens, such as the application of biological control agents. This study aims to identify the potential biocontrol mechanisms of the bacterial strain TSO2 by sequencing, annotation, and mining its genome. The draft genome of strain TSO2 was sequenced through the Illumina Miseq platform and presented 4,242,212 bp, 43.9% G+C content, 300,069 bp N50, 5 L50, 47 contigs, 96 RNAs, and 4,432 predicted coding DNA sequences. Besides, the presence of 86 CDS of agricultural importance involved in virulence, disease, defense, iron acquisition, and secondary and phosphate metabolisms was detected. On the other hand, seven putative secondary metabolite gene clusters involved in biocontrol activity were identified in the genome of strain TSO2. <em>Bacillus </em>sp. TSO2 contains a great number of biosynthetic gene clusters which supports its biocontrol activity against phytopathogenic fungi. Thus, this strain needs to be further studied as a potential bioactive ingredient for the biopesticide formulation due to its high potential as a biological control agent.</p>

Efficacy of Fungicides against Bipolaris sorokiniana under in vitro and in vivo Conditions

Spot blotch of wheat caused by Bipolaris sorokiniana could be effectively and economically controlled by two foliar sprays of either Propiconazole or Hexaconazole @ 0.1 per cent at fifteen days interval but on the basis of cost- benefit ratio Hexaconazole had an edge over Propiconazole. The harmful effects of fungicides to human and environment, there have been proved useful and economical in the control of spot blotch. Non systemic and systemic foliar fungicides belonging to the dithiocarbamate and Triazoles are found to be effective. Foliar applications of systemic fungicides between heading and grain filling stages, are cost effective. Propiconazole, Hexaconazole and Difenaconazole + Propiconazole at 250 ppm completely inhibited the mycelial growth of B. sorokiniana. Carbendazim and Copper oxychloride also causes and complete inhibition but at 500 and 1000 ppm, respectively but Mancozeb could not give complete inhibition even at 1000 ppm.

STUDY ON RESEARCH WORKS AND FUTURE RESEARCH DIRECTIONS OF POST-GRADUATE PROGRAM AT PATHOLOGY DEPARTMENT, IAAS, RAMPUR, CHITWAN, NEPAL

The Institute of Agriculture and Animal Science (IAAS) under Tribhuwan University (TU) has been carrying out various disciplinary and system research works through post-graduate students' research and publishing their findings through the M.Sc.Ag and Ph.D. thesis dissertations. Various thesis written by researchers under IAAS were collected and the appraisal of pathological research works on major cereals, vegetable crops, legume crops, oilseed crops and high-value crops along with ideas on management practices was done with the help of a thorough literature review. Data were gathered from IAAS/TU libraries, Rampur Library, Kritipur library, GAASC library and IAAS journals. A total of 68 types of research were conducted at IAAS. It is revealed that major diseases associated with cereals area brown spot of rice, rice blast, yellow rust of wheat, helminthosporium leaf blight of wheat, spot blotch of wheat and leaf blast of finger millet. Similarly, diseases of vegetables include late blight of potato, a white mold of french beans. The major diseases of legumes are wilt of lentil & chickpea, powdery mildew of pea, anthracnose of soybean and those of oilseeds are mainly leaf blights. Large cardamom, greatly known as high- value crop, is found to be suffered from Chirkey Foorkey and leaf blight diseases. Fungal pathogens cause most of the diseases in almost all crops. The management practices at their best results included the use of biological agents along with commonly available fungicides. The study found out a research gap in agricultural pathology as well. It also luminated the future area of research works that is lacking in current research works

Spot blotch disease of wheat as influenced by foliar trichome and stomata density

Spot blotch, caused by Bipolaris sorokiniana, is a potent biotic constraint to wheat crop leading to substantial yield abatement in warm humid South Asia (e.g. India, Nepal and Bangladesh) and other major wheat-growing countries such as Canada, the United States, Brazil and Australia. A set of 98 bread wheat genotypes were evaluated over two growing seasons to investigate the relationship among foliar trichome, stomata density, and susceptibility to the spot blotch pathogen. The higher density of trichomes (90-140 mm −2 ) on the adaxial surface of flag leaves entrapped 32-74 mm −2 pathogen spores. It restricted the dew droplets size (0.15–0.3 mm 2 ) on the flag leaves and thus prevented direct contact between the spores and the leaf epidermis. Trichome density was negatively associated with the disease development and spore germination but positively associated with grain size and the number of spores entrapped on trichomes per mm 2 . Conversely, stomata density was positively associated with the development of the disease. Cluster and principal component analyses divided trichome density, the number of spores trapped on trichome per mm 2 , and thousand grain weight into one group and stomata density, the area under disease progress curve, percent spore germination, and dew scale into another group. The results from this study provided a novel insight to breeders where the selection of bread wheat genotypes with high trichome (90-140 mm −2 ) and low stomata density (72-90 mm −2 ) on foliage could enhance spot blotch resistance in wheat. • Spot blotch of wheat reduces up to 30% yield in the Indian subcontinent. • The relationship among foliar trichome, stomata density, and susceptibility to the spot blotch pathogen was studied. • The higher density of trichomes (90-140 mm −2 ) entrapped 32-74 mm −2 spores prevented direct contact between the spores and the leaf epidermis. • This study assists breeders for the selection of bread wheat genotypes with high trichomes and low stomata density on foliage could enhance spot blotch resistance.

Weather-based models to forecast spot blotch disease (Bipolaris sorokiniana) of wheat (Triticum aestivum) in North Bengal

Experiment was laid with wheat (Triticum aestivum L.) genotypes Sonalika (susceptible check) and HD 2967 (popular variety) at Pundibari, Coochbehar, India (26o23’52”N, 89o23’26”E) on two dates of post-rainy (rabi) seasons of 2018 and 2019 at one-year interval. Data of experiments conducted previously at Pundibari were also used. Correlation values indicated that percent disease severity and Area under Disease Progress Curve on cv. Sonalika and HD 2967 had significant (P<0.1) correlations with maximum temperature and morning relative humidity. Weighted interactions between maximum temperature and morning relative humidity, maximum temperature and rainfall, minimum temperature and afternoon relative humidity, minimum temperature and rainfall, morning and afternoon relative humidity were also significant (P<0.1). Cultivar-specific models were developed to predict the severity of the spot blotch disease (Bipolaris sorokiniana) on the crop. This will allow the growers to make need-based timely effective application of fungicides prior to inception of the disease. Here we report only the models that were found effective based on validation in the two years. As per available literature, this report seems to be the first of its kind for forecasting spot blotch of wheat.

Assessment of wheat genotypes based on genotype-by-environment interaction for durable resistance to spot blotch disease in hot spot

Spot blotch, an important foliar fungal disease caused by Bipolaris sorokiniana (Sacc.) Shoemaker [stat. anam.], is the influential production restraint over the global wheat-growing regions. A set of eight diverse wheat genotypes including a few breeding lines from Uttar Banga Krishi Viswavidyalaya and commonly accepted susceptible cultivars were screened for spot blotch disease and grain yield across five different locations in West Bengal, India, under environments for natural disease infestation in post-rainy seasons of 2018–2019 and 2019–2020. The present investigation revealed significant variation among the genotypes for spot blotch resistance in different environments as a result of genotype main effect and genotype environment interaction. This study also recorded two genotypes as resistant against spot blotch disease over the five locations. Identified resistant genotypes increased grain yield as a consequence of resistance offered against spot blotch disease suggesting the possibility of considering disease resistance as a must-have trait in all the wheat cultivars that could be identified for cultivation in the North-Eastern Plain Zone of India. Two genotypes resistant to spot blotch recorded 1.26–1.46 times higher grain yield over control under disease pressure that can be recommended for identification and exploited in a resistance breeding program for wheat spot blotch disease-prone region.

Incidence of spot blotch of wheat in Eastern Uttar Pradesh

Bipolaris sorokiniana was mainly responsible for causing spot blotch of wheat in Eastern Uttar Pradesh. The disease appeared 5 to 8 weeks after wheat sowing and the symptoms advanced after heading stage and spreaded very fast. The dark brown necrotic spots (boat shaped) occured on the leaves, crowns and stems with or without yellow halo around these. Lesions on the leaves in the begging were few mm in size and extended as elongated dark brown spots and later on coalesced resulting into blight. In severe cases, at flowering stage 60 to 80 per cent leaf areas was turned into necrotic lesions. Intensity of spotting increased with the increase in the age of plants and reached maximum between boot to maturity stage of the crop. Minute spots were also observed on leaf sheaths, nodes, internodes and the glumes. Survey of five districts were conducted in Eastern Uttar Pradesh, clearly indicate that dominant pathogen responsible for causing spot blotch of wheat is Bipolaris sorokiniana because nearly eighty per cent of sample yielded Bipolaris sorokiniana in both the years. Maximum Bipolaris sorokiniana was recorded in Jaunpur 27&23 in the years of 2018-2019 respectively and minium B. sorokiniana was recorded in 9&6 in Faizabad districts in the years of 2019-2020 respectively.