U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
3-2017
Citation
ANNUAL REPORT OF THE BEAN IMPROVEMENT COOPERATIVE, No. 60, March 2017. Published by USDA.
Abstract
INTRODUCTION Several diseases have contributed to limit the bean crop yield. Among the diseases white mold (Sclerotinia sclerotiorum) and anthracnose (Colletotrichum lindemuthianum) stand out. One way to reduce losses caused by both S. sclerotiorum and C. lindemuthianum is using resistant cultivars. Recurrent selection allows improving quantitative traits such as white mold resistance, as well as improve several characters simultaneously, if the selected parents have alleles for these traits. LEITE et al. (2016) and DIAS (2015) performed recurrent selection for resistance to white mold intercrossing several parents using the circulant diallel procedure and, some of them had anthracnose resistance alleles (Co-4² and Co-5). Although there was no selection for those alleles, they may have remained in the population after successive selective cycles. The objective of this study was to verify anthracnose resistance among the selected progenies in the cycle VII, VIII and IX from recurrent selection program for white mold resistance, and to identify the presence of resistance alleles Co-4² and Co-5.
MATERIAL AND METHODS Twenty-two progenies of cycle VII, 23 of cycle VIII and 21 of cycle IX, all of them of the S0:4 generation and derived of recurrent selection program for resistance to white mold, and the controls Pérola (susceptible) and M20 (resistant due to Co4² allele) were evaluated. The experiments were set up using a completely randomized design, with two replicates and plots with 16 plants in greenhouse. The races 65 and 1609 were inoculated in all experiments according to PIO-RIBEIRO & CHAVES (1975) and, the anthracnose reaction was evaluated visually using a descriptive scale with scores from 1 to 9 (SCHOONHOVEN & PASTORCORRALES 1987).
In order to verify the presence of the Co-4² resistance allele, DNA of the progenies and the controls were extracted through a procedure similar to the used by PARRELLA et al. (2008), and the PCR was carried out using the primer SAS13, which is linked to Co-4² allele at the distance of 0,34cM.
Comments
U.S. government work.