Use of molecular markers to accelerate the breeding of common bean lines resistant to rust and anthracnose - Breeding of common bean lines resistant to rust and anthracnose aided by molecular markers

The main goal of this work was to introduce resistance genes for rust, caused by Uromyces appendiculatus, and anthracnose, caused by Colletotrichum lindemuthianum, in an adapted common bean cultivar through marker-assisted backcrossing. DNA fingerprinting was used to select plants genetically closer to the recurrent parent which were also resistant to rust and to race 89 of C. lindemuthianum. DNA samples extracted from the resistant parent (cv. Ouro Negro), the recurrent parent ( cv. Ruda), and from BC1, BC2 and BC3 resistant plants were amplified by the RAPD technique. The relative genetic distances in relation to the recurrent parent varied between 9 and 59% for BC1, 7 and 33% for BC2, and 0 and 7% for BC3 resistant plants. After only three backcrosses, five lines resistant to rust and anthracnose with, approximately, 0% genetic distance in relation to the recurrent parent were obtained. These lines underwent field yield tests in two consecutive growing seasons and three of them presented a good yield performance, surpassing in that sense their parents and most of the reference cultivars tested.