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Genetic Basis of Bacterial Wilt in Common Bean
Bacterial wilt caused by Curtobacterium flaccumfaciens pv. flaccumfaciens is one of the four most harmful bacterial diseases of the common bean (Phaseolus vulgaris L.). The disease was first reported in South Dakota in 1921; although it was controlled at that time, the disease spread throughout the world; therefore the pathogen was classified as high risk with quarantine category A2. In the1970s, the introgression of natural resistance to develop the cultivar ‘Emerson’ was one of the strategies to control the disease. However, no new cultivars have been developed, and few sources of resistance are known. To better understand the genetics of resistance to bacterial wilt, G16829, a resistant wild genotype, and Raven, a susceptible cultivar, were crossed and six generations: parents (resistant parent (G16829), susceptible parent (Raven)), direct F1 (G16829/Raven), reciprocal F1 (Raven/G16829), F2, backcross to the resistant parent (BC1P1), and backcross to the susceptible parent (BC1P2); as well as a biparental population of recombinant inbred lines (RILs) were generated. The populations were evaluated in greenhouses in Scottsbluff and Lincoln, Nebraska. All F1 plants were susceptible, so it was deduced that susceptibility was the dominant trait. This result was confirmed due to the lack of segregation in BC1P2. The F2 segregated in a 13:3 (susceptible: resistant) ratio indicated an inhibitory action of epistasis where two dominant genes are involved, one hiding the effect of the other. The RIL population was genotyped by whole-genome sequencing. A genetic map was generated by the bin mapping process involving the combination of adjacent SNPs with the same genotype according to recombination breakpoints. A major quantitative trait loci (QTL) was detected on chromosome Pv08, which accounted for 35% of the variation in resistant response. This dissertation is the first to report a QTL of resistance to bacterial wilt in common bean, which implies a significant step in the knowledge of the genetics of the disease for the development of new cultivars.
Genetics|Plant sciences|Plant Pathology
Sanchez Betancourt, Erika Patricia, "Genetic Basis of Bacterial Wilt in Common Bean" (2021). ETD collection for University of Nebraska - Lincoln. AAI28865517.