Genetics And Mechanisms Of Bruchid Resistance In Selected Common Bean (Phaseolus Vulgaris L.) Landraces From Tanzania And Malawi.

ABSTRACT

Bean bruchids are the devastating pests of common bean which causes huge losses during storage. Two landraces Kalubungula and KK25 were identified to be resistant to bruchid infestation and damage but the mechanism and genetics of resistance were unknown. The aim of this study was to (i) characterize the storage protein related to resistance in these landraces (ii) determine genomic region and map QTL’s related to resistance (iii) phenotype progenies response to bean bruchid infestation.Two mapping populations KSy and KSw and Nagaga x KK25 recombinant inbred lines was created in this study. We reported no association between resistance to the storage proteins in KSw and KSy. Resistance in Nagaga x KK25 recombinant inbred lines reported to be due to storage proteins Arcelin-5 and Phytohaemagglutinin found at 25KDa. On determination of genomic region and QTL’s related to bruchid resistance, a total of 328 novel single nucleotide polymorphisms (SNP’s) were reported from KSy and 435 SNP’s from KSw assembled in 11 linkage groups of P. vulgaris. QTL’s associated with bruchid resistance were mapped on linkage group five (PV05) and linkage group nine (PV09) in KSy and KSw mapping populations except for seed size and 50% adult bruchid emergence. Seed size QTL’s were distributed on different linkage groups indicating little or no association between the resistance and seed size. To evaluate the response of progenies to bruchid infestation, 15 lines out of 53 (28.3%) were resistant in KSy population and 5 lines (10.4%) out of 48 were resistant in KSw population. Resistant lines identified may be important sources of bruchid resistance in breeding programs and the QTL’s may be of importance in marker development for marker assisted selection in common bean.