Evidence of isolate-specificity in non-hypersensitive resistance in spring wheat (Triticum aestivum) to wheat leaf rust

Isolate-specific aspect of non-hypersensitive resistance in wheat to wheat leaf rust was studied at seedling stage in the green house. Isolate-specific response of non-hypersensitive resistance was assessed from latency period (LP) and infection frequency (IF) of two single-pustule isolates of Puccinia triticina in 26 spring wheat cultivars/lines. Small but significant cultivar x isolate interactions were observed for LP and IF in seedlings of host genotypes. Isolate specific effect for LP at seedling stage was consistent and reproduced in a repeated experiment; however, the interaction for IF was inconsistent and was not reproducible. The inconsistency in cultivar x isolate interaction may be due to some non-genetic origin. The result suggested that a gene-for-gene relationship could exist between non-hypersensitive resistance genes in the host and genes in pathogen.