ABSTRACT
Resistance to anthracnose, caused by Colletotrichum capsici and C. acutatum, was investigated in Capsicum baccatum PBC80 and PBC1422 and C. chinense PBC932. Mature green and ripe fruit were inoculated with 13 isolates of the two Colletotrichum species PBC80 contained the broadest spectrum of resistance to both Colletotrichum species because none of the isolates were able to infect the genotype. At both fruit maturity stages, PBC1422 was infected by only Colletotrichum acutatum. PBC932 at ripe fruit stage was infected by both C. capsici and C. acutatum, except for one isolate, 158ci, that did not infect PBC932. PBC932 at the mature green fruit stage was infected by only C. acutatum. An intraspecific cross between PBC80 and PBC1422 was developed to determine inheritance of resistance to C. acutatum. Anthracnose resistance was assessed at mature green and ripe fruit stages using 0 to 9 disease severity scores. Frequency distribution of the disease scores in the F(2) and BC(1) populations suggested a single recessive gene responsible for the resistance at mature green fruit stage and a single dominant gene for the resistance at ripe fruit stage. Linkage analysis between the two genes identified in both fruit maturity stages showed the genes to be independent. Based on phenotypic data, the two newly identified genes, co4 and Co5, from PBC80 appeared to be different loci from the co1 and co2 previously identified from PBC932 and will be valuable sources of resistance to anthracnose in chili breeding programs.
Subject(s)
Capsicum/genetics , Colletotrichum/pathogenicity , Genes, PlantABSTRACT
Eleven isolates of Colletotrichum capsici were screened on nine chili genotypes derived from four cultivated species of Capsicum: Capsicum annuum, C. baccatum, C. chinense, and C. frutescens. Host reactions were assessed 9 days after inoculation by microinjection of spores into the pericarp of red fruit. A set of disease scales, with 0 to 9 scores, were developed for anthracnose infection of each Capsicum sp. based on percent lesion size in relation to fruit size, appearance of necrotic or water-soaked tissue, and presence of acervuli. Three pathotypes, PCc1, PCc2, and PCc3, were identified according to differential qualitative infection of fruit of C. chinense genotypes PBC932 and C04714. PCc1 was the most virulent pathotype, infecting all genotypes of C. annuum, C. chinense, and C. frutescens, whereas PCc3 was the least virulent pathotype, infecting only the genotypes C. annuum and C. frutescens. Quantitative infection occurred in all chili genotypes except for genotypes of C. baccatum, where no infection occurred, demonstrating various levels of aggressiveness of isolates within pathotypes.
