Genome-Wide Analysis of NBS-LRR-Encoding Genes in Sorghum and Comparative Sequence Analysis of NBS-LRR-Encoding Genes in Grass Species

Plant nucleotide-binding site (NBS)-leucine-rich repeat (LRR)-encoding genes play an important role in defending plants from infection of various pathogens including virus, bacterial and fungi. The objective of this study was to characterize the sequence structure, variation, and relationship of NBS-LRR-encoding genes in Sorghum bicolor (S. bicolor) and a few other grass species. In total, 88 NBS-LRR-encoding genes were identified by comprehensive analysis on 39,441 sorghum protein sequences with InterProScan 5 standalone version. Based on the occurrence of conserved protein domains such as coiled-coil (CC), NBS, LRR and other domains (X), these NBS-LRR-encoding genes were classified into four subgroups: NBS-LRR, CC-NBS-LRR, X-NBS-LRR and X-CC-NBS-LRR. The chromosomal distribution of the genes was unbalanced ranged from one on chromosome 1 (1 %) to 21 (24%) on chromosome 5, with 43 NBS-LRR-encoding genes (49%) clustered in 16 clusters. The duplications were detected among 24 NBS-LRR genes (27%), which were subsequently grouped into eight gene families. Orthologs of five NBS-LRR-encoding genes were identified from the genomes of S. bicolor, Brachypodium distanchyo (B. distanchyo), Zea mays (Z. mays), and Oryza sativa (O. sativa). Sequence comparison showed the closest relationship between S. bicolor and Z. Mays and highest distance between Z. mays and B.distancho. This study will facilitate identification of new disease resistance genes in S. bicolor and will contribute to understanding the relationship of divergence and evolutionary process of the NBS-LRR genes in grass species.