Publication Date:
2012-06-22
Description:
Background: Non-host resistance (NHR) confers plant species immunity against the majority of microbialpathogens and represents the most robust and durable form of plant resistance in nature. Asone of the main genera of rust fungi with economic and biological importance, Puccinia infects almost all cereals but is unable to cause diseases on legumes. Little is known about themechanism of this kind of effective defense in legumes to these non-host pathogens. Results: In this study, the basis of NHR in broad bean (Vicia faba L.) against the wheat stripe rustpathogen, Puccinia striiformis f. sp. tritici (Pst), was characterized. No visible symptomswere observed on broad bean leaves inoculated with Pst. Microscopic observations showedthat successful location of stomata and haustoria formation were significantly reduced in Pstinfection of broad bean. Attempted infection induced the formation of papillae, cell wallthickening, production of reactive oxygen species, callose deposition and accumulation ofphenolic compounds in plant cell walls. The few Pst haustoria that did form in broad beancells were encased in reactive oxygen and callose materials and those cells elicited cell death.Furthermore, a total of seven defense-related genes were identified and found to be upregulatedduring the Pst infection. Conclusions: The results indicate that NHR in broad bean against Pst results from a continuum of layereddefenses, including basic incompatibility, structural and chemical strengthening of cell wall,posthaustorial hypersensitive response and induction of several defense-related genes,demonstrating the multi-layered feature of NHR. This work also provides useful informationfor further determination of resistance mechanisms in broad bean to rust fungi, especially theadapted important broad bean rust pathogen, Uromyces viciae-fabae, because of strongsimilarities and association between NHR of plants to unadapted pathogens and basalresistance of plants to adapted pathogens.
Electronic ISSN:
1471-2229
Topics:
Biology
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