Botrydial and botcinins produced by Botrytis cinerea regulate the expression of Trichoderma arundinaceum genes involved in trichothecene biosynthesis

Abstract

Trichoderma arundinaceum IBT 40837 (Ta37) and Botrytis cinerea produce the sesquiterpenes harzianum A (HA) and botrydial (BOT), respectively, and also the polyketides aspinolides and botcinins (Botcs), respectively. We analysed the role of BOT and Botcs in the Ta37-B. cinerea interaction, including the transcriptomic changes in the genes involved in HA (tri) and ergosterol biosynthesis, as well as changes in the level of HA and squalene-ergosterol. We found that, when confronted with B. cinerea, the tri biosynthetic genes were up-regulated in all dual cultures analysed, but at higher levels when Ta37 was confronted with the BOT non-producer mutant bcbot2Δ. The production of HA was also higher in the interaction area with this mutant. In Ta37-bcbot2Δ confrontation experiments, the expression of the hmgR gene, encoding the 3-hydroxy-3-methylglutaryl coenzyme A reductase, which is the first enzyme of the terpene biosynthetic pathway, was also up-regulated, resulting in an increase in squalene production compared with the confrontation with B. cinerea B05.10. Botcs had an up-regulatory effect on the tri biosynthetic genes, with BotcA having a stronger effect than BotcB. The results indicate that the interaction between Ta37 and B. cinerea exerts a stimulatory effect on the expression of the tri biosynthetic genes, which, in the interaction zone, can be attenuated by BOT produced by B. cinerea B05.10. The present work provides evidence for a metabolic dialogue between T. arundinaceum and B. cinerea that is mediated by sesquiterpenes and polyketides, and that affects the outcome of the interaction of these fungi with each other and their environment.

Involvement of Trichoderma harzianum Epl-1 Protein in the Regulation of Botrytis Virulence- and Tomato Defense-Related Genes

“…Furthermore, BOT has been reported as a repressor of the gene cluster responsible for the biosynthesis of harzianum A (HA), a trichothecene produced by T. arundinaceum that lacks in vivo phytotoxicity. HA is involved in biocontrol activity and promotes the expression of plant defense-related genes ( Malmierca et al, 2012 , 2016 ). In this present work, we analyzed the role that Epl-1 has in the modulation of the BOT biosynthetic gene cluster expression in B. cinerea during direct confrontation assays and identified Epl-1 as an important regulator of BOT biosynthesis.…”

“…Furthermore, in the absence of Epl-1, a higher degradation of the Trichoderma spp. cell wall would be expected resulting in the release of small elicitor molecules that can upregulate B. cinerea virulence-related genes ( Malmierca et al, 2016 ). Thus, demonstrating the important function of Epl-1 during the mycoparasitism process ( Gomes et al, 2015 ).…”

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

“…In addition, BOT seems to be toxic for B. cinerea itself as the application of exogenous metabolite (50-250 ppm) inhibits the growth of the fungus . Finally, a recent study by Malmierca et al (2016) proposes that BOT may be involved in the communication with other microorganisms. Indeed, confrontation assays with Trichoderma arundinaceum suggest that BOT has a role in limiting the production of the sesquiterpene harzianum A.…”

The Search for Quorum Sensing in Botrytis cinerea: Regulatory Activity of Its Extracts on Its Development

“…In strains of B. cinerea submitted to chemical stress, a QS effect was reported with several sporogenic eremophil-9-ene-1,11-diol derivatives in cultures after more than three weeks of fermentation [28]. The regulation of gene expression in Trichoderma arundinaceum by botrydial and botcinins has been previously established in a process named by the authors as "a metabolic dialogue", but, from a biochemical point of view, can be considered as a QS effect [29]. Even some mycotoxins seem to play a role more related to QS than to animal cells, as has been shown in Fusarium [30,31].…”