Histopathological analysis of incompatible and compatible interaction of Puccinia striiformis f.sp. tritici on wheat at early infection stage

Stripe rust of wheat (Puccinia striiformis f.sp. tritici; Pst) incurs substantial yield losses in wheat worldwide. Two Indian Pst pathotypes 38S102 (I) and 46S119 (Yr9 virulence) showed incompatible and compatible interaction respectively in variety PBW 343. The histopathological study using confocal microscopy revealed that during incompatible interaction comparatively longer abortive germ tubes are produced with a rapid response at early stages of infection but with no fungal colonization. Whereas, in compatible interaction, germ tubes were shorter with infection peg formed above the stomata subsequently leading to colonization. The detailed microscopic observations showed that necrotic regions were more prominent in incompatible interaction than compatible interaction. This information would aid in understanding the growth and virulence mechanism of stripe rust pathogen in wheat.