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

Abstract

a b s t r a c tBotrydial (BOT) is a non-host specific phytotoxin produced by the polyphagous phytopathogenic fungus Botrytis cinerea. The genomic region of the BOT biosynthetic gene cluster was investigated and revealed two additional genes named Bcbot6 and Bcbot7. Analysis revealed that the G + C/A + T-equilibrated regions that contain the Bcbot genes alternate with A + T-rich regions made of relics of transposable elements that have undergone repeat-induced point mutations (RIP). Furthermore, BcBot6, a Zn(II) 2 Cys 6 putative transcription factor was identified as a nuclear protein and the major positive regulator of BOT biosynthesis. In addition, the phenotype of the DBcbot6 mutant indicated that BcBot6 and therefore BOT are dispensable for the development, pathogenicity and response to abiotic stresses in the B. cinerea strain B05.10. Finally, our data revealed that B. pseudocinerea, that is also polyphagous and lives in sympatry with B. cinerea, lacks the ability to produce BOT. Identification of BcBot6 as the major regulator of BOT synthesis is the first step towards a comprehensive understanding of the complete regulation network of BOT synthesis and of its ecological role in the B. cinerea life cycle.

Biosynthesis of abscisic acid in fungi: identification of a sesquiterpene cyclase as the key enzyme in Botrytis cinerea

“…While Bcstc1/Bcbot2 and Bcstc5/Bcaba5 are now identified as the key genes for the biosynthesis of botrydial and ABA respectively, the role of the other Bcstc genes remains unknown. Most B. cinerea strains produce botrydial in significant amounts in standard culture conditions, i.e., 7–10 µg ml −1 (Reino et al ., ; Pinedo et al ., ; Porquier et al ., ), but the other sesquiterpenes are often below the detection level. In comparison, there is an apparent redirection of FPP‐derived metabolism in the strain ATCC58025, resulting in a significant overproduction of ABA.…”

Gapless genome assembly of Colletotrichum higginsianum reveals chromosome structure and association of transposable elements with secondary metabolite gene clusters

“…The overall TE content of C. higginsianum (7%) is comparable to that reported previously for C. graminicola (12.2%) and C. orbiculare (8.3%) [13, 91] and other phytopathogenic fungi with similar sized genomes such as Z. tritici (16.7%), S. sclerotiorum (12.9%), B. cinerea (3.7%) and V. dahliae (12.3%) but is strikingly less than in L. maculans (33.3%), Blumeria graminis f. sp. hordei (76.4%) and Melampsora larici-populina (51.7%) [6, 8, 25, 92, 93]. LTR elements are the most abundant TEs in C. higginsianum , as reported in other fungi, e.g.…”

The formation of sesquiterpenoid presilphiperfolane and cameroonane metabolites in the Bcbot4 null mutant of Botrytis cinerea

“…The polyketides 2-7 and 9-15 were also isolated and identified by comparison of their spectroscopic data with those of authentic samples. 19 Six new compounds (16)(17)(18)(19)(20)(21) were isolated from the fractions of medium polarity and purified by further chromatography including HPLC. The 1 H and 13 C NMR spectra suggested that they possessed sesquiterpenoid structures.…”

“…In the HMBC spectrum (see Table S3, ESI †) there were correlations between H-2 and C-3, C-4 and C-8 and between H-15 and C-1. Thus the structures of 16-18 were presilphiperfolan-8α,10β,14-triol (16), 8α,14-dihydroxypresilphiperfolan-10-one (17) and 8α,10β,14-trihydroxypresilphiperfol-1-ene (18).…”

“…15,18,19 The metabolites which were produced by the null mutants Bcbot3Δ and Bcbot4Δ were analysed after five days fermentation 19 at the time of maximum botrydial production (Scheme 1). 20 The fermentation of the BcBOT4 mutant revealed that the related monooxygenase was involved in the hydroxylation at C-11 (C-4 in botrydial numbering, see 8) of the presilphiperfolan-8-ol intermediate (8) in the biosynthesis.…”