Department of Agricultural Botany, University of Sydney, N.S.W., Australia
*Present address: CIMMYT, Londres 40, Mexico 6, D. F.
W3299 (P.I. 243064) a selection from Giza 139 × Gabo was found to have 3 undescribed genes SrL1, SrL2 and SrL3 for stem rust resistance of which two, SrL1 and SrL2, were closely linked.
It also carried two undescribed genes for leaf rust resistance. The first, a temperature sensitive gene designated lrG1, conditioned a “3+” infection type at 60°-65°F and “0;” at 85°F, with strain 162-1, 2, 3, 4. It was ineffective against strain 135-2, 3, 4, 5 at both the temperatures. The second gene designated lrG2 only operated in adult plants and conditioned immunity.
The study revealed the basis for the low average coefficient of infection shown by this parent and underlined the importance of incorporation of several genes in a cultivar.
