Sequencing and Transcriptional Analysis of the Biosynthesis Gene Cluster of Abscisic Acid-Producing Botrytis cinerea

Abstract

Botrytis cinerea is a model species with great importance as a pathogen of plants and has become used for biotechnological production of ABA. The ABA cluster of B. cinerea is composed of an open reading frame without significant similarities (bcaba3), followed by the genes (bcaba1 and bcaba2) encoding P450 monooxygenases and a gene probably coding for a short-chain dehydrogenase/reductase (bcaba4). In B. cinerea ATCC58025, targeted inactivation of the genes in the cluster suggested at least three genes responsible for the hydroxylation at carbon atom C-1' and C-4' or oxidation at C-4' of ABA. Our group has identified an ABA-overproducing strain, B. cinerea TB-3-H8. To differentiate TB-3-H8 from other B. cinerea strains with the functional ABA cluster, the DNA sequence of the 12.11-kb region containing the cluster of B. cinerea TB-3-H8 was determined. Full-length cDNAs were also isolated for bcaba1, bcaba2, bcaba3 and bcaba4 from B. cinerea TB-3-H8. Sequence comparison of the four genes and their flanking regions respectively derived from B. cinerea TB-3-H8, B05.10 and T4 revealed that major variations were located in intergenic sequences. In B. cinerea TB-3-H8, the expression profiles of the four function genes under ABA high-yield conditions were also analyzed by real-time PCR.

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

“…Moreover, Bcstc5/Bcaba5 appeared to be approximately sixfold more highly expressed in ATCC58025 than in B05.10. As ABA is a compound of interest for biotechnology companies, several screening and mutagenesis programs were conducted to improve the ability B. cinerea to produce this compound at an industrial scale, i.e., up to 6 g l −1 (Gong et al ., ; Ding et al ., ; Shi et al ., ). The resulting ABA‐overproducing strains like ATCC58025 are impaired in conidiation and other developmental processes.…”

“…Nevertheless the key enzyme, i.e., the sesquiterpene cyclase (STC) that is expected for the upstream cyclization step has not been identified so far. The described bcaba1–4 cluster does not include any STC‐coding gene suggesting that this gene is located elsewhere in the genome (Siewers et al ., ; Gong et al ., ). Complete genome sequencing of the two B. cinerea model strains B05.10 and T4 allowed the identification of five and six STC‐coding genes respectively (Amselem et al ., ).…”

ABA Suppresses Botrytis cinerea Elicited NO Production in Tomato to Influence H2O2 Generation and Increase Host Susceptibility

“…Alternatively, the Pseudomonas syringae effector HopAM1 enhances virulence via manipulation of sensitivity to ABA rather than initiating ABA biosynthesis ( Goel et al, 2008 ). Moving beyond bacterial delivery of effectors, some fungal pathogen encode ABA biosynthetic genes and have been shown to synthesize ABA including Cercopsora, Fusarium, Rhizoctonia (reviewed by Cao et al, 2011 ), and of particular relevance to this current study, B. cinerea ( Gong et al, 2014 ). Considering the mechanics of ABA promoted susceptibly, there is evidence that this causes reduced alterations in cell wall characteristics, ROS generation and callose deposition as well as defense gene expression ( Asselbergh et al, 2007 ; de Torres-Zabala et al, 2007 ; Cao et al, 2011 ).…”

“…A similar link between ABA and suppression of ROS during attack by B. cinerea has been made in Arabidopsis ( L’Haridon et al, 2011 ). Given such observations it is unsurprising that B. cinerea strains can encode genes for ABA biosynthesis ( Gong et al, 2014 ).…”

Interaction points in plant stress signaling pathways

“…Furthermore, several studies support the role of ABA in promoting virulence in plant‐ Botrytis interactions. ABA overproduction has been associated with enhanced virulence in some strains (Siewers et al , Gong et al , Ding et al ) and treatment with exogenous ABA was shown to promote virulence (Shaul et al ). The WRKY33 transcription factor is required for the downregulation of plant ABA biosynthesis and thus promotes immunity against Botrytis (Liu et al ).…”