Archivio Journal of Plant Pathology

Abstract:

Nonhost resistance (NHR) confers plants immunity to most microbial pathogens. Resistance responses in nonhost pepper cv. A11 and the incompatible host wheat cv. Suwon 11 against the stripe rust fungus Puccinia striiformis f. sp. tritici (Pst) were studied histochemically. Similarly high germination rates of Pst were observed on both nonhost and resistant host. However, the majority of germ tubes failed to form substomatal vesicles and fewer haustoria formed in the nonhost interaction, while the ratio of H2O2 accumulation was considerably high in pepper. During a further incubation period, no secondary hyphae were found in nonhost pepper-Pst. In contrast, significantly higher proportion of haustoria and a much lower production of H2O2 and secondary hyphae were detectable in the incompatible host resistance deployed by wheat. The incidence of hypersensitive cell death was found to be slightly higher in the nonhost interaction. These results indicate that H2O2 and hypersensitive cell death play important roles in the NHR of pepper to Pst, and nonhost and host resistance may share similar mechanisms.