Influence of salicylate and abscisic acid on the resisitance of tomato to biotrophic and necrotrophic pathogens

Plants protect themselves against pathogenes by putting up physical and biochemical barriers through processes involving hormone-mediated signalling. The plant defence hormone, Salicylic acid (SA), was tested for its role in the response of tomato and tobacco to a necrotroph, Botrytis cinerea and a biotroph, Oidium neolycopersici). In tomato the SA defence pathway activated both basal and induced resistance against B. cinerea but not against O. neolycopersici. The reverse effects were observed in tobacco, indicating that plant defence responses activated by the SA-dependent pathway depend on the specific host–pathogen system. Another plant hormone, abscisic acid (ABA), interacts antagonistically with SA and other hormones involved in plant defence. Testing the role of ABA in tomato revealed that basal levels of the hormone favour infection by B. cinerea, O. neolycopersici and the necrotrophic bacterium, Erwinia chrysanthemi. The ABA-deficient sitiens mutant of tomato was resistant to all three pathogens compared to the wild type (WT). Exogenous ABA suppressed the resistance of sitiens to all three pathogens and increased the infection of WT plants by E. chrysanthemi but did not affect WT susceptibility to B. cinerea and O. neolycopersici. It is concluded that genetically induced ABA-deficiency in tomato confers broad spectrum resistance to pathogens of varying life styles but production of the opposite effect (higher susceptibility) by exogenous ABA enrichment is not obvious and depends on the target pathogen and probably on the method of application. Treatment of WT tomato plants with chemical inhibitors of ABA biosynthesis resulted in lower B. cinerea infection without altering the plant ABA content. This led to the hypothesis that abiotic stress from chemical treatment possibly triggered defence against pathogens. Investigating other forms of abiotic stress showed that drought stress increased ABA content alongside a decrease in infection by B. cinerea and O. neolycopersici while salt stress lowered infection by O. neolycopersici but had no effect on B. cinerea and did not alter plant ABA levels. It is concluded that abiotic stress stimulates disease resistance in tomato probably through multiple pathways that may vary depending on the nature of the stress and may not necessarily involve ABA.

Author dc:creator

• Enow, A

Contributors dc:contributor

• Höfte, M

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

und

Identifier

https://biblio.ugent.be/publication/469422
http://doi.org/1854/6354
https://biblio.ugent.be/publication/469422/file/1877343

OAI identifier oai:identifier

oai:archive.ugent.be:469422