Spot blotch (SB), caused by Bipolaris sorokiniana, is a devastating disease of wheat globally, especially in South Asia and South America. Understanding the genetics of resistance to SB is important for developing breeding strategies to improve resistance. A panel of 301 genotypes from Afghanistan was phenotyped over two crop seasons using a mixture of virulent B. sorokiniana isolates and genotyped using DArTSeq to obtain genome‐wide markers. Fifty genotypes (16.6%) showed disease scores less than the resistant control. Principal component analysis using the genotypic data clustered the genotypes into five different groups. Among models used for genome‐wide association mapping, the multilocus mixed model, and fixed and random model circulating probability unification algorithms were most effective in identifying significant marker‐trait associations (MTA). Twenty‐five MTAs at p ≤ .001 were identified on chromosomes 1A, 1B, 1D, 2B, 2D, 3A, 3B, 4A, 5A, 5B, 6A, 7A, and 7D, indicating the quantitative nature of resistance to SB. Phenotypic variation explained by these markers ranged from 2.0% to 17.7%, and genomic regions on the chromosomes 1D, 2D, 3A, 3B, 4A, 5A, and 5B coincided with loci identified in previous studies. Three single nucleotide polymorphism (SNP) markers on chromosomes 1B (SNP 1113207) and 5A (SNPs 5411867 and 998276) were significant in both crop seasons as well as in the combined analysis across seasons. Marker 5411867 is close to Vrn‐A1, shown to be associated with SB in previous studies. Furthermore, among known SB resistance genes, Sb2 on chromosome 5B was predicted to be significant in this panel.

Tan spot caused by Pyrenophora tritici-repentis ( Ptr ) is an important disease of wheat in many wheat producing areas of the world. A genome wide association study (GWAS) was conducted using 11,401 SNP markers of the Illumina Infinium 15K Bead Chip with whole genome coverage to identify genomic regions associated with resistance to tan spot in a diverse panel of 184 wheat genotypes originating from South Asia and CIMMYT. The GWAS panel was phenotyped for seedling resistance to tan spot with Ptr race 1 in two greenhouse experiments. Besides CIMMYT germplasm, several lines from South Asia (India, Bangladesh and Nepal) showed good degree of resistance to tan spot. Association mapping was conducted separately for individual experiments and for pooled data using mixed linear model (MLM) and Fixed and random model Circulating Probability Unification (FarmCPU) model; no significant MTAs were recorded through the MLM model, whereas FarmCPU model reported nine significant MTAs located on chromosomes 1B, 2A, 2B, 3B, 4A, 5A, 5B, 6A, and 7D. The long arms of chromosomes 5A and 5B were consistent across both environments, in which the Vrn-A1 locus was found in identified region of chromosome 5A, and MTA at IACX9261 on 5BL appears to represent the resistance gene tsn 1 . MTAs observed on chromosomes 1B, 2A, 2B, 3B, 4A, 6A, and 7D have not been reported previously and are likely novel.

Wheat ( Triticum aestivum L.) crop health assumes unprecedented significance in being the second most important staple crop of the world. It is host to an array of fungal pathogens attacking the plant at different developmental stages and accrues various degrees of yield losses owing to these. Tilletia indica that causes Karnal bunt (KB) disease in wheat is one such fungal pathogen of high quarantine importance restricting the free global trade of wheat besides the loss of grain yield as well as quality. With global climate change, the disease appears to be shifting from its traditional areas of occurrence with reports of increased vulnerabilities of new areas across the continents. This KB vulnerability of new geographies is of serious concern because once established, the disease is extremely difficult to eradicate and no known instance of its complete eradication using any management strategy has been reported yet. The host resistance to KB is the most successful as well as preferred strategy for its mitigation and control. However, breeding of KB resistant wheat cultivars has proven to be not so easy, and the low success rate owes to the scarcity of resistance sources, extremely laborious and regulated field screening protocols delaying identification/validation of putative resistance sources, and complex quantitative nature of resistance with multiple genes conferring only partial resistance. Moreover, given a lack of comprehensive understanding of the KB disease epidemiology, host-pathogen interaction, and pathogen evolution. Here, in this review, we attempt to summarize the progress made and efforts underway toward a holistic understanding of the disease itself with a specific focus on the host-pathogen interaction between T. indica and wheat as key elements in the development of resistant germplasm. In this context, we emphasize the tools and techniques being utilized in development of KB resistant germplasm by illuminating upon the genetics concerning the host responses to the KB pathogen including a future course. As such, this article could act as a one stop information primer on this economically important and re-emerging old foe threatening to cause devastating impacts on food security and well-being of communities that rely on wheat.

Pre-harvest sprouting (PHS) having adverse effects on both crop yields and quality, is one of the major constraints of wheat production in areas with high rainfall. In the north-eastern parts of India and also many areas of the world receiving rainfall during the late maturity stages of the crop affects both grain yields and quality. PHS trait is polygenic trait and affected by number of environmental factors. The available diversity in germplasm for the trait is very limited and for improving tolerance to PHS newer sources needs to be identified. The primary cause of pre-harvest sprouting is the breakdown or lacking of seed dormancy under humid and wet conditions along with the degradation of starch in the germinated seeds due to enhanced alpha amylase activity. This review describes the factors affecting the pre-harvest sprouting tolerance, genes associated with it, physiological, biochemical and molecular mechanism involved, screening technique and breeding approaches to develop PHS s tolerant wheat genotypes.

Background This study aimed to investigate the rhizosphere bacterial isolates’ antagonistic property against the soil-borne fungal phytopathogen, Sclerotium rolfsii Sacc. (Athelia rolfsii (Curzi) Tu & Kimbrough). The chemical control of the disease caused by S. rolfsii is economically and environmentally unsustainable, and therefore, a bio-control agent in the form of rhizospheric bacteria is gaining importance. Main body Five rhizospheric Bacillus species viz. B. subtilis subsp. Subtilis str.168 (accession no. MH283878), B. siamensis strain PDA 10 (accession no. MH283879), B. amyloliquefaciens strain 1034 (accession no. MH283880), B. velezensis strain FZB42165 (accession no. MH283881), and B. atrophaeus strain NBRC 15539 (accession no. MH283882) were assessed for their antagonistic potential against S. rolfsii based on 3 different screening methods. Among these, 100% fungal growth inhibition by all 5 Bacillus spp. was observed in the novel ring method, whereas in the dual culture method, the maximum growth inhibition was (58%) exhibited by the strain NBRC 15539 of B. atrophaeus. The antagonistic activity showed by the modified dual culture method was also relatively high, and the highest activity (93.7%) was shown by the strain NBRC 15539 of B. atrophaeus. Besides, the Bacillus sp. was also evaluated for their plant growth-promoting attributes and other properties such as the production of siderophore, HCN, amylase, protease, lipase, and ammonia, including their assessment for chitinase and cellulase activity. Conclusion The study provided empirical evidence of Bacillus sp. antagonistic potential against S. rolfsii and should be of contributive value in developing a biocontrol agent for this highly important crop fungal pathogen.