Isolation and Characterization of NBS-LRR Genomic Fragments and The Development of SNAP Markers for Fusarium oxysporum fsp. cubense Resistance in Banana

Fusarium wilt because of F. oxysporum fsp. cubense (Foc) infection is a major disease infecting banana in Indonesia, especially the Tropical Race 4 (TR4). Development of resistance variety is needed to sustain banana cultivation in this region. Isolation and characterization of resistance genes from local banana cultivars should be useful to support development of future Foc resistance cultivars. The objectives of this research were to isolate NBS-LRR containing genomic fragments from various banana cultivars with differential responses against TR4 isolate of Foc. The genomic fragments were then sequenced and the sequences were used to identify single nucleotide amplified polymorphism (SNAP) markers. The informativeness of identified SNAP markers were then evaluated using an array of banana cultivars with either known or unknown responses againts TR4 isolate. Alele variabilities of identified  SNAP markers among tested banana cultivars evaluated and the possible association among the markers with Foc resistance were tested. Results of the experiment indicated that the designed degenerate primers for NBS-LRR conserved regions were able to amplify 500 bp genomic fragments from Foc resistance cultivars. As many as 91 fragments were sequenced and 16 fragments were positively identified as coding for NBS-LRR domain. The rest of the fragments were either too small or contained unidentified introns making them untranslatable. Out of the 16 NBS-LRR sequences, 19 SNAP markers were developed and tested against an array of banana cultivars having differential responses against Foc. Results of the SNAP marker evaluation will be presented in the poster presentation.