Greenhouse Evaluation of Adult-Plant Resistance Conferred by the Gene Lr34 to Leaf Rust of Wheat

Abstract

The latent period of Puccinia recondita f. sp. tritici in flag leaves of line RL6058 (with gene Lr34) was most extended at greenhouse temperatures of 13-17 C compared with that in the leaf-rust-susceptibel wheat (Triticum aestivum) cultivar Thatcher. A day/night regime of 25-29/13-15 c also increased latent period in RL6058, but no such differences between RL6058 and Thatcher were evident at continuous 26-30 C. Uredinia per square centimeter of flag leaf surface were fewer on RL6058 than on Thatcher. Temperature did not influence the expression of this character in RL6058, but more uredinia developed on young flag leaves than on older ones. The size of uredinia on flag leaves depended on the ambient greenhouse temperature and was more restricted at 25-29/13-15 C and continuous 13-17 C than at 26-30 C. Because of the assumed durability of Lr34 and its ability to interact with other genes to enhance the level of resistance, more deliberate exploitation of Lr34 could be justified. This study indicated that selection for Lr34 can be done in greenhouse with adequate temperature control.