TRANSFER OF ANGULAR LEAF SPOT RESISTANCE GENE FROM 'CORNELL 49-242' TO THE CARIOCA CULTIVAR RUDA

摘要

Angular leaf spot occurs in almost all regions where beans are cultivated, especially under mild temperature conditions and high relative humidity. The use of susceptible cultivars in such environmental conditions favors the occurrence of the disease,thus leading to great yield losses. The development of new cultivars resistant to this disease is hindered by the pathogenic variability of its causative agent, Phaeoisariopsis griseola (SARTORATO and ALZATE-MARIN, 2004; SARTORATO, 2006). The BIOAGRO/UFV Bean Breeding Program has been using the backcrossing method for the introgression of resistance genes to this disease. Simultaneous backcrossing programs are conducted for each resistance source. Allelism studies carried out by CAIXETA et al. (2005) detected one single gene named Phg-3 in cultivar Cornell 49-242, confirming the results obtained by NIETSCHE et al. (2000). The resistance conferred by this gene is complementary to those of other sources that are presently being used in the BIOAGRO/UFV Bean Breeding Program. So, its use would increase the resistance spectrum of the cultivars released by the Program.