INHERITANCE OF ADDITIONAL RESISTANCE FROM NEAR-ISOGENIC LINES FOR THE GENE LR3 AGAINST INDIAN LEAF RUST RACES

Abstract

Near-isogenic leaf rust resistant lines Thatcher + Lr3Ka, Prelude+Lr3Ka and Prelude+Lr3s in were found to carry a yet undescribed field resistance effective against a mixture of highly virulent variants 77-1 and 77-2 of the Indian leaf rust race 77. Against another highly virulent culture from race 108 showing avirulence on Lr3, these three lines as well as the near-isogenic lines Thatcher+Lr3do and Thatcher+Lr3bg were resistant both at seedling and adult plant stages. The seedling resistance of each of these five near-isogenic lines to race 108 was caused by a recessive gene. The seedling resistance of Thatcher+Lr3do and Thatcher+Lr3bg to race 108 was due to the 'lame gene or a gene tightly linked to Lr3. This resistance segregated independently of the recessive seedling resistance gene identified from the near-isogenic lines Thatcher+Lr3ka, Prelude+Lr3ka and Prelude+Lr3sin. The field resistance of isogenic lines Thatcher+Lr3ka, Prelude+Lr3ka and Prelude+Lr3sin was due to a dominant and a recessive gene in each. The factors causing field resistance in each of these three near-isogenic lines were different.