Jari P. T.
1Department of Plant Biology, Genetic Centre, SLU, PO Box 7080, S-750 07 Uppsala, Sweden; 2Max-Planck-Institut für Züchtungsforschung, Carl-von-Linne Weg 10, D-50829 Köln, Germany; 3Department of Biotechnological Science, Kinki University, Wakayama, 649-6493, Japan
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Accepted 15 November 1999.
Resistance to Potato virus A (PVA) was examined in a diploid cross involving Solanum tuberosum subsp. andigena as a resistance source. Hypersensitive resistance (HR) to PVA cosegregated with extreme resistance (ER) to Potato virus Y conferred by the dominant gene Ryadg on chromosome XI. Hence, HR to PVA was controlled by a novel, dominant resistance gene closely linked to Ryadg, or Ryadg recognized both viruses but conferred a different type of resistance to each virus. The HR prevented systemic infection with PVA following mechanical inoculation but not following graft inoculation. Another, recessive gene, ra, that may be linked or even allelic with Ryadg fully blocked vascular transport of PVA in graft-inoculated plants. Hence, a possibility exists that the genes for the three types of resistance to potyviruses may reside at the same, resistance gene-rich chromosome region syntenic in solanaceous species and might be related. The gene ra acted against all of the three PVA strains tested and, therefore, the avirulence determinants could not be mapped. However, also, PVA strain-specific resistance was found in the progeny. It was overcome by mutations introduced into the viral genome-linked protein and the helper component proteinase and/or the coat protein.
© 2000 The American Phytopathological Society