Expression profiling and mutant analysis reveals complex regulatory networks involved in Arabidopsis response to Botrytis infection

Abstract

). † These authors contributed equally to this study. SummaryThe expression profiles of Botrytis-inoculated Arabidopsis plants were studied to determine the nature of the defense transcriptome and to identify genes involved in host responses to the pathogen. Normally resistant Arabidopsis wild-type plants were compared with coi1, ein2, and nahG plants that are defective in various defense responses and/or show increased susceptibility to Botrytis. In wild-type plants, the expression of 621 genes representing approximately 0.48% of the Arabidopsis transcriptome was induced greater than or equal to twofold after infection. Of these 621 Botrytis-induced genes (BIGs), 462 were induced at or before 36 h postinoculation, and may be involved in resistance to the pathogen. The expression of 181 BIGs was dependent on a functional COI1 gene required for jasmonate signaling, whereas the expression of 63 and 80 BIGs were dependent on ethylene (ET) signaling or salicylic acid accumulation, respectively, based on results from ein2 and nahG plants. BIGs encode diverse regulatory and structural proteins implicated in pathogen defense and abiotic and oxidative-stress responses. Thirty BIGs encode putative DNA-binding proteins that belong to ET response, zinc-finger, MYB, WRKY, and HD-ZIP family transcription-factor proteins. Fourteen BIGs were studied in detail to determine their role in resistance to Botrytis. T-DNA insertion alleles of ZFAR1 (At2G40140), the gene encoding a putative zinc-finger protein with ankyrin-repeat domains, showed increased local susceptibility to Botrytis and sensitivity to germination in the presence of abscisic acid (ABA), supporting the role of ABA in mediating responses to Botrytis infection. In addition, two independent T-DNA insertion alleles in the WRKY70 gene showed increased susceptibility to Botrytis. The transcriptional activation of genes involved in plant hormone signaling and synthesis, removal of reactive oxygen species, and defense and abiotic-stress responses, coupled with the susceptibility of the wrky70 and zfar1 mutants, highlights the complex genetic network underlying defense responses to Botrytis in Arabidopsis.

The novel elicitor AsES triggers a defense response against Botrytis cinerea in Arabidopsis thaliana

“…7). Similar cross-talk events have been described for the B. cinerea-induced protein kinase mutant bik1, that shows inhibition of PDF1.2 but increased SA-induced defense responses [45] and for the activator of SA and repressor of JA-responsive genes, the transcription factor WRKY70 [46,47]. More work would be required to determine the exact localization of these cross-talks in relation to pathogen invasion to determine their relevance.…”

Ripening-Regulated Susceptibility of Tomato Fruit toBotrytis cinereaRequiresNORBut NotRINor Ethylene

“…In unripe tomato fruit, B. cinerea causes transcriptional and histochemical changes that support the conclusion that some of the responses by the fruit to a pathogen are resistance responses similar to those that have been observed by others in vegetative plant organs (Benito et al, 1998;Diaz et al, 2002;AbuQamar et al, 2006). Although unripe fruit are resistant to B. cinerea, the interaction with the fungus also results in transcriptional changes that are expressed as uninfected fruit ripen, which suggests that the fungus induces fruit ripening processes that ultimately render ripe fruit susceptible.…”

“…A complex cross talk of signaling pathways is known to regulate pathogen virulence and the resistance of vegetative tissues to B. cinerea. Ethylene and jasmonic acid limit infections of Arabidopsis and tomato leaves (Ferrari et al, 2003;Mengiste et al, 2003;AbuQamar et al, 2006;Zheng et al, 2006), but the role of salicylic acid is ambiguous (Ferrari et al, 2003). However, since ethylene promotes ripening, it may contribute to fruit susceptibility, in contrast to its role in infected leaves.…”

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana

“…Also in some plant-pathogen interactions, ABA seems to play a negative regulatory function by inactivating other defense signaling pathways, such as those mediated by SA or JA/ eT (Anderson et al 2004;Takahashi et al 2004). Other examples for this negative function were observed between tomato and Erwinia chrysanthemi (Asselbergh et al 2008), or Arabidopsis with the necrotrophic fungi Botrytis cinerea (Abuqamar et al 2006).…”