Resistance to potato virus Y (pathotype 1–2) in Capsicum annuum and Capsicum chinense is controlled by two independent major genes

Summary

The genetic basis of the resistance to a pepper strain of potato virus Y (PVY pathotype 1–2) was investigated in two lines: Capsicum annuum ‘Criollo de Morellos 334’ and Capsicum chinense ‘PI 159236’. F1, backcrosses, and F2 populations were produced using C. annuum ‘Magda’ as the susceptible parent. Segregation ratios indicated that the resistance in C. annuum ‘Criollo de Morellos 334’ is governed by a nuclear, single dominant gene with a very high but incomplete penetrance. On the other hand, the resistant response of C. chinense ‘PI 159236’ is associated with the presence of a major recessive gene with an apparently complete penetrance. The failure in recovering or detecting PVY from/in the inoculated leaves of both resistant genotypes is strongly suggestive that both genes are acting by preventing the multiplication of the virus in the leaf tissue. Both mechanisms of resistance closely resemble either an operational immunity or a single-cell hypersensitive reaction to PVY pathotype 1–2. The name Ry 1–2 is suggested for the resistance gene from ‘Criollo de Morellos 334’. The gene for resistance to PVY pathotype 1–2 identified in C. chinense ‘PI 159236’ may be the same designated et ^c1, which is mentioned to be allelic to the et ^av locus. The phenotypic expression of the et ^av gene was characterized in C. annuum ‘Avelar’ as a tolerant but not immune or hypersensitive reaction against some potyviruses in Florida. These data suggest that a critical reexamination of the allelic relationships at the locus et should be performed.