Diversity of beans grown in Kyrgyzstan and marker-aided breeding for resistance to Bean common mosaic virus and anthracnose

Sammanfattning: Common bean (Phaseolus vulgaris L.) is an important export crop in Kyrgyzstan since the end of the 20th century. Kyrgyzstan produces about 70,000 t of common beans per year, which provides jobs to 76% of the population in the Talas region. Information about genetic diversity of common beans helps to select appropriate genetic material to be used for breeding programs. Accessions originating from both Mesoamerican and Andean gene pools, including the main Kyrgyz common bean market types were analyzed using simple sequence repeats (SSR) and qualitative morphological traits. The similarity matrices generated from the molecular and morphological data were well correlated (r = 0.49''). The cluster analysis of both data sets grouped the accessions according to their gene pools of origin, where Mesoamerican accessions were more diverse than Andean accessions. Both SSR and qualitative morphological markers were suitable for assigning cultivars to their gene pools of origin. Furthermore, information about traits of interest for Kyrgyz farmers has been gained. We found that Bean common mosaic virus strain NL6 and anthracnose affect this crop and reduce its grain yield significantly in Kyrgyzstan. The susceptible Kyrgyz cultivars Ryabaya, Kytayanka and Lopatka were included as recurrent parents in a backcrossing breeding scheme for introducing host plant resistance to these diseases from donor cultivars. After the 4th backcross, seeds (color, shape, size) and pods (shape) were similar to the respective recurrent parent. The sequence characterized amplified region (SCAR) markers SW13, SBD5 and SCAreoli were used successfully in marker-aided backcrossing for pyramiding the I, bc-12 and Co-2 genes, which provide host plant resistance to BCMV and anthracnose, respectively. Inoculation tests with anthracnose races delta and gamma, virus strain NL3, and DNA markers confirmed the presence of resistance genes in the offspring.