Relationship of genes for resistance to protection by diffusates from incompatible interactions of Phaseolus vulgaris with Colletotrichum lindemuthianum

Abstract

Phaseolus vulgaris hypocotyls were protected against cultivar-pathogenic races of Colletotrichum lindemuthianum by a factor which diffused into water droplets on incompatible interactions. The factor protected the cultivar from which it was obtained. It also protected cultivars having the same disease reaction to a nonpathogenic race as the cultivar from which the factor was obtained. At least two different factors can be produced in incompatible interactions. Conidial germination fluids and mycelial sonicates of beta and gamma races did not protect. A mixture of diffusates from incompatible interactions of the beta race on Perry Marrow and gamma race on Topcrop protected both cultivars from challenges by the gamma and beta races, respectively. When diffusates from incompatible and compatible interactions on Perry Marrow were mixed, the level of protection was reduced on Perry Marrow to a challenge by a cultivar-pathogenic race of C. lindemuthianum. Diffusates from C. truncatum, a nonpathogen of bean, on Perry Marrow and Stringless Green Pod reduced the size of lesions produced on these cultivars in response to challenges by cultivar-pathogenic races of C. lindemuthianum.