Inheritance of er1-Based Broad-Spectrum Powdery Mildew Resistance in Pea (Pisum sativum L.).

The knowledge about the nature and number of gene(s) controlling resistance is the pre-requisite for the success of powdery mildew resistance breeding program in pea. Seven biparental cross combinations involving three highly resistant (It-96, No. 267 and JI 2302) and two highly susceptible (Climax and PF-400) pea genotypes were evaluated for their response to powdery mildew disease. The quantitative microscopic scale of disease assessment coupled with detached leaf assay was employed for the evaluation of disease response of the crosses and their generations (F1, F2, BCs, and BCr) against two highly virulent conidial isolates of Erysiphe pisi. The disease response of 677 F2 plants has revealed a typical monohybrid Mendelian 3 (susceptible): 1 (resistant) segregation, moreover, the evaluation of 254 BCr plants gave a perfect 1 (susceptible): 1(resistant) segregation. No complementation was observed among all the F1 plants of three complementation crosses, suggesting that the same allele (er-1) conditions complete and broad-spectrum resistance in all the powdery mildew resistant pea genotypes in homozygous recessive form. [ABSTRACT FROM AUTHOR]