Universidad Cat—lica de Bras’lia. Brasil.
Universidad Cat—lica de Bras’lia
RESUMEN (ABSTRACT)
Banana (Musa spp.) is a major crop in the tropics and sub-tropics, contributing to food security and livelihoods. Many cultivars are sterile triploids or diploids, with evolution via somatic mutation resulting in a restricted genetic base lacking resistance to pests and disease. Fertile wild species of Musa acuminata, by contrast, can represent sources of resistance to biotic challenges. Numerous disease resistance genes (R-genes) have been characterized in plants, conferring resistance to bacteria, viruses, fungi and nematodes. Identification and introgression of such R-genes in Musa provides new opportunities for genetic improvement. Our group has identified NBS-LRR-type resistance gene analogs (RGAs) in the resistant wild diploid M. acuminata ssp. burmannicoides ÔCalcutta 4Õ, with further characterization of this R-gene family, together with cytoplasmic receptor-like kinases (RLKs) with extracellular LRRs, in M. acuminata cultivars contrasting in resistance to Mycosphaerella leaf spot diseases. Candidate gene discovery via comparative transcriptome analysis of gene expression from infected leaf material during Musa-Mycosphaerella interactions has also been conducted using both Sanger and Next Generation Sequencing approaches. Ongoing in silico data analysis has identified statistically significant differential expression in genes related to resistance or defense, including type 3 metallothioneins, germin-like proteins, ferredoxin and glutathione S-transferase, pathogenesis-related proteins, thioredoxin, glycolate oxidase, a putative ethylene Ð responsive small GTP Ð binding protein, superoxide dismutase, a putative stress enhanced protein, and an auxin Ð repressed protein like protein. Validation of differential gene expression is being conducted via qRT-PCR. Candidate R-genes offer potential for accelerating banana genetic improvement via both plant transformation and marker assisted breeding.