Genome-Wide Identification and Characterization of Nucleotide-Binding Site (NBS) Resistance Genes in Pineapple

Pineapple is a major tropical fruit and the most important crop processing CAM photosynthesis. It originated in southwest Brazil and northeast Paraguay and survived the harsh, semi-arid environment. Disease resistance genes have contributed to the survival and thriving of this species. The largest class of disease resistance (R) genes in plants consists of genes encoding nucleotide-binding site (NBS) domains. The sequenced genome of pineapple (Ananas comosus (L.) Merr.) provides a resource for analyzing the NBS-encoding genes in this species. A total of 177 NBS-encoding genes were identified using automated and manual analysis criteria, and these represent about 0.6 % of the total number of predicted pineapple genes. Five genes identified here contained the N-terminal Toll/Interleukin-l receptor (TIR) domain, and 46 genes carried the N-terminal Coiled-Coil (CC) motif. A majority of these NBS-encoding genes (84 %) contained a leucine-rich repeat (LRR) domain. A total of 130 of 177 (73 %) of these NBS-encoding genes were distributed across 20 pineapple linkage groups. The identification and characterization of NBS genes in pineapple yielded a valuable genomic resource and improved understanding of R genes in pineapple, which will facilitate the development of disease resistant pineapple cultivars.