The Sesquiterpene Botrydial Produced by Botrytis cinerea Induces the Hypersensitive Response on Plant Tissues and Its Action Is Modulated by Salicylic Acid and Jasmonic Acid Signaling

Abstract

Botrytis cinerea, as a necrotrophic fungus, kills host tissues and feeds on the remains. This fungus is able to induce the hypersensitive response (HR) on its hosts, thus taking advantage on the host's defense machinery for generating necrotic tissues. However, the identity of HR effectors produced by B. cinerea is not clear. The aim of this work was to determine whether botrydial, a phytotoxic sesquiterpene produced by B. cinerea, is able to induce the HR on plant hosts, using Arabidopsis thaliana as a model. Botrydial induced the expression of the HR marker HSR3, callose deposition, and the accumulation of reactive oxygen species and phenolic compounds. Botrydial also induced the expression of PR1 and PDF1.2, two pathogenesis-related proteins involved in defense responses regulated by salicylic acid (SA) and jasmonic acid (JA), respectively. A. thaliana and tobacco plants defective in SA signaling were more resistant to botrydial than wild-type plants, as opposed to A. thaliana plants defective in JA signaling, which were more sensitive. It can be concluded that botrydial induces the HR on its hosts and its effects are modulated by host signaling pathways mediated by SA and JA.

Molecular analysis of the early interaction between the grapevine flower and Botrytis cinerea reveals that prompt activation of specific host pathways leads to fungus quiescence

“…; Rossi et al . ), further confirmed that the fungus put in place several strategies to invade the grapevine flowers. Nonetheless, there was no visible disease symptoms observed in the post‐inoculation observations despite the presence of B. cinerea confirmed by the plating‐out experiment (Fig.…”

Beneficial ‘unintended effects’ of a cereal cystatin in transgenic lines of potato, Solanum tuberosum

“…This pleiotropic effect of recombinant cystatins , also observed in plants treated with synthetic Cys protease inhibitors or transformed with DNA sequences to silence Cys proteases expression [35], would be correlated with an increase of cystatin:Cys protease ratios in planta preventing the release of free Cys proteases to initiate cell death [36]. This ectopic phenotype could represent, along with the constitutive over-expression of stress-related proteins, a major hurdle to the progression of the necrotroph, which relies on cell death induction to generate dead tissues and successfully colonize the host plant [37-41]. …”

The botrydial biosynthetic gene cluster of Botrytis cinerea displays a bipartite genomic structure and is positively regulated by the putative Zn(II)2Cys6 transcription factor BcBot6

“…The cellular target of BOT remains unknown but the recent work of Rossi et al (2011) on Arabidopsis thaliana suggests that BOT induces the hypersensitive response through the salicylic acid and jasmonic acid signaling pathways, thereby acting as an effector of plant cell death. This biological activity fits with the available transcriptomic data: the BOT gene cluster is up-regulated during infection of different hosts including A. thaliana and Vitis vinifera (Gioti et al, 2006;Kelloniemi et al, 2015).…”