Genome-wide association study for spot blotch resistance in Afghan wheat germplasm |
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Authors: | Naresh K Bainsla Rahul M Phuke Xinyao He Vikas Gupta Santosh K Bishnoi Rajiv K Sharma Najibeh Ataei Susanne Dreisigacker Philomin Juliana Pawan K Singh |
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Institution: | 1. Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India;2. ICAR-Indian Agriculture Research Institute, Indore, India;3. International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico;4. ICAR-Indian Institute of Wheat and Barley Research, Karnal, India;5. Agricultural Research Institute of Afghanistan (ARIA), Ministry of Agriculture, Irrigation and Livestock (MAIL), Kabul, Afghanistan |
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Abstract: | 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. |
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Keywords: | Afghan wheat landrace Bipolaris sorokiniana DArTSeq disease resistance genome-wide association study Triticum aestivum |
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