The Quest for resistance genes, A GWAS analysis for Leaf rust and Powdery mildew resistance in Nordic spring barley (Hordeum vulgare L.)

Summary

Barley (Hordeum vulgare L.) is the fourth most important cereal crop in the world after rice, wheat, and maize. Powdery mildew and leaf rust are two most important and widespread fungal diseases of barley caused by Blumeria graminis and Puccinia hordei, respectively. Development and deployment of resistant cultivars is one of the most sustainable management strategies. A Genome-wide association study (GWAS) was performed to identify significant Marker Trait Association for powdery mildew and leaf rust resistance in two multi-parent advanced generation intercross (MAGIC) populations, MAGIC 6 & MAGIC 7. Barley panel contained 91 genotypes from MAGIC 6 and 97 genotypes from MAGIC 7 which were investigated individually and all together (91+97=188 genotypes). Genome-Wide Linkage Disequilibrium (LD) decay was estimated at 35 Mbp for combined panel and STRUCTURE analyses revealed the unstructured populations. In total, we found 14 Marker Trait Associations (MTAs) and 9 QTL for powdery mildew and 14 MTAs and 9 QTL were identified for leaf rust. Most of the QTL regions have some well-known resistance genes belong to Leucine-Rich Repeat (LRR) family and some other defense-related proteins peroxidases and chitinases are also found. Haplotype analysis and favorable allelic combinations will be evaluated in the upcoming days. Overall, the results from this work can improve the efficiency of barley breeding program in the Nordic region, and the identified markers can be used for marker-assisted selection, and the nature of identified candidate genes can be assessed in further studies.