Herança da resistência ao Colletotrichum lindemuthianum (Sacc. ET Magn.) Scrib. na cultivar de feijoeiro comum México 222

Abstract

México 222 is a Mesoamerican cultivar resistant to 77 races of Colletotrichum lindemuthianum. Considering the importance of the cultivar Mexico 222, the present work has as objective to study the inheritance of resistance of this cultivar to races 7 and 23 of C. lindemuthianum, and to verify the independence of the genes present in Mexico 222 in relation to alleles of the loci Co-4, Co-7 and Co-9. The inheritance study of resistance was conducted in the F² populations from the crosses Mexico 222 (resistant to race 7) × Michigan Dark Red Kidney (susceptible to race 7) and Mexico 222 (resistant to race 23) × Widusa (susceptible). On the other hand, the allelism studies were performed in F² generations from the crosses Mexico 222 × MSU 7.1, Mexico 222 × PI 207262 and Mexico 222 × BAT 93, inoculated with race 7 of C. lindemuthianum. The results showed that the cultivar Mexico 222 has two dominant genes for resistance to race 7 of C. lindemuthianum and only one dominant gene for resistance to race 23. F² generations derived from the crosses between the cultivars Mexico 222 and MSU 7.1, PI 207262 and BAT 93, inoculated with race 7 revealed the presence of allelism. These results demonstrated that the alleles present in the cultivars Mexico 222, MSU 7.1, PI 207262 and BAT 93 conferring resistance to race 7 are alleles of the same locus. Since Mexico 222 presents a different spectrum of resistance in relation BAT 93 and PI 2072629 cultivars, these results indicate that Mexico 222 has a second allele different from Co-3 and Co-9. The authors propose the symbol Co-33 to name the second allele present in Mexico 222, which confers resistance to race 7 of C. lindemuthianum.