INHERITANCE OF RESISTANCE TO POTATO-VIRUS-Y AND POTATO-VIRUS-X IN HYBRID SOLANUM-PHUREJA X SOLANUM-STENOTOMUM DIPLOID POTATOES

Inheritance of resistance to infection by potato virus Y (PVY) strain o and potato virus X (PVX) U.S. common strain of hybrid Solanum phurej a-S. stenotomum diploid potatoes was elucidated, Extreme resistance an d susceptible clones to infection by either PVY or PVX were intercross ed in separate crossing blocks to generate 22 PVY and 19 PVX hybrid fa milies, which were evaluated for resistance to PVY and PVX, respective ly, Probabilities associated with chi(2) values strongly supported the hypothesis that resistance to infection by PVY was controlled by comp lementary action of at least two dominant genes, Additionally, probabi lities associated with total, pooled, and heterogeneity chi(2) values for resistance to susceptibility ratios of 1:3, 1:1, and 9:7 did not s upport rejecting this hypothesis, Similarly, probabilities associated with chi(2) values estimated, assuming a dominance modification of two genes as controlling resistance to infection by PVX, strongly support ed this hypothesis, Also, probabilities associated with pooled chi(2) values for 3:1 and 1:1 ratios of resistance and susceptibility did not support rejecting this hypothesis, In addition, a gene-dosage depende nce model was proposed to explain the genetics of necrotic reactions t o infection by PVX: probabilities associated with segregation ratios o f less than half of the evaluated families supported this genetic mode l; lack of complete fit in the other families might be due to the mark ed influence of environmental conditions on expression of necrotic rea ctions.