Tlalnepantla 64 (PI 207262) is an important source of genes for resistance to common bean anthracnose, caused by Colletotrichum lindemuthianum. However, these genes have not been fully characterized. Inheritance studies using crosses involving PI 207262 show that two independent genes confer resistance to anthracnose. Allelism tests showed that the genes are located at distinct loci from the previously identified resistance genes Co-1, Co-2, Co-3, Co-5, Co-6, and Co-10. Also, no segregation was observed in relation to Co-4, Co-4 2 , Co-9, and to the gene present in cultivar Widusa, indicating that PI 207262 harbors alleles of these genes. We conclude that PI 207262 harbors two anthracnose resistance genes, Co-4 and Co-9. The Co-4 allele of PI 207262 would be different from Co-4 and Co-4 2 and it is proposed Co-4 3 as the genetic symbol for this resistance allele. As PI 207262 is the parent of BAT 93, the Co-9 symbol represents the gene of both cultivars. Also, one allele of Co-9 gene was detected in cultivar Widusa.

No abstract

The inheritance of anthracnose resistance of the common bean (Phaseolus vulgaris L.) differential cultivar G 2333 to Colletotrichum lindemuthianum races 73 and 89 was studied in crosses with the susceptible cultivar Rudá. The segregation ratios of 15 : 1 in the F2 and 3 : 1 in the backcrosses to Rudá indicate that for each of the races tested there are two independent resistance loci in G 2333. A random amplified polymorphic DNA (RAPD) molecular marker (OPH181200C) linked in resistance to race 73 was identified in a BC3F2:3 population derived from crosses between Rudá and G 2333. A RAPD molecular marker OPAS13950C, previously identified as linked to gene Co‐42, was also amplified in this population. Co‐segregation analyses showed that these two markers are located at 5.6 (OPH181200C) and 11.2 (OPAS13950C) cM of the Co‐42 gene. These markers were not present in BC1F2:3 plants resistant to race 89 indicating that this population carries a different resistance gene. DNA amplification of BC1F2:3 plants with RAPD molecular marker OPAB450C, previously identified as linked to gene Co‐5, indicated that this gene is present in this population.