INHERITANCE IN HEXAPLOID WHEAT OF ADULT-PLANT LEAF RUST RESISTANCE DERIVED FROM AEGILOPS SQUARROSA

Abstract

The inheritance of adult-plant leaf rust resistance derived from Aegilops squarrosa was studied in a synthetic hexaploid wheat. The hexaploid was produced by combining the AABB component extracted from the common wheat cultivar Canthatch with Ae. squarrosa var. strangulata R.L. 5271 which has adult-plant resistance to several races of leaf rust. Resistance is conferred by a single, partially dominant gene that is inherited independently of Lr12 and L13, two previously identified genes for adult-plant leaf rust resistance. Although monogenic inheritance was observed, this gene must be influenced by the genetic background since its level of resistance was somewhat reduced during successive backcrosses to Thatcher.This new gene for adult-plant leaf rust resistance was linked with each of the genes for foliage waxiness and threshability with a recombination value of 15.6 ± 2.5% and 6.0 ± 1.5%, respectively. The genes for foliage waxiness and threshability were associated with an estimated linkage value of 17.4 ± 2.5%.