Inheritance of resistance to clover yellow vein virus in Pisum sativum

Abstract

Most of the cultivars of Pisum sativum resistant to bean yellow mosaic virus (BYMV) were found to be resistant to clover yellow vein virus (CYVV). However, some accessions from Ethiopia (PI 193586 and PI 193835) and India (PI 347464, PI 347465, PI 347466, PI 347467, and PI 347492) were resistant to CYVV, but susceptible to BYMV. Conversely, others from China (PI 391630) and the USSR (PI 262818) were resistant to BYMV, but susceptible to CYVV, indicating that resistance to these two viruses is conferred by distinct genetic entitles. In the BYMV+CYVV-resistant cultivar Bonneville, resistance to CYVV was found to be inherited monogenlcally recessive (cyv). This gene appears to be closely linked to that conferring resistance to BYMV (mo), which is located on the second chromosome. In the accessions from Ethiopia and India, resistance to CYVV is conditioned by a second recessive gene (cyv-2), that is situated in a different linkage group. In the lines from China and the USSR, resistance to BYMV is conferred by mo. The possible origin of two distinct genes for resistance to the same isolate of CYVV is discussed.