Putative Nonribosomal Peptide Synthetase and Cytochrome P450 Genes Responsible for Tentoxin Biosynthesis in Alternaria alternata ZJ33

Abstract

Tentoxin, a cyclic tetrapeptide produced by several Alternaria species, inhibits the F1-ATPase activity of chloroplasts, resulting in chlorosis in sensitive plants. In this study, we report two clustered genes, encoding a putative non-ribosome peptide synthetase (NRPS) TES and a cytochrome P450 protein TES1, that are required for tentoxin biosynthesis in Alternaria alternata strain ZJ33, which was isolated from blighted leaves of Eupatorium adenophorum. Using a pair of primers designed according to the consensus sequences of the adenylation domain of NRPSs, two fragments containing putative adenylation domains were amplified from A. alternata ZJ33, and subsequent PCR analyses demonstrated that these fragments belonged to the same NRPS coding sequence. With no introns, TES consists of a single 15,486 base pair open reading frame encoding a predicted 5161 amino acid protein. Meanwhile, the TES1 gene is predicted to contain five introns and encode a 506 amino acid protein. The TES protein is predicted to be comprised of four peptide synthase modules with two additional N-methylation domains, and the number and arrangement of the modules in TES were consistent with the number and arrangement of the amino acid residues of tentoxin, respectively. Notably, both TES and TES1 null mutants generated via homologous recombination failed to produce tentoxin. This study provides the first evidence concerning the biosynthesis of tentoxin in A. alternata.

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

“…Cochliobolus miyabeanus was the first non-Alternaria species shown to produce tentoxin (de Bruyne et al, 2016). Tentoxin occurs in many Alternaria species and is known to induce chlorosis due to damage to the F 1 -ATPase of chloroplasts in sensitive plants (Li et al, 2016). Although the TES gene is present in the E. turcicum genome, read count values were low and do not indicate that tentoxin plays a role in pathogenicity of E. turcicum on maize.…”

Dual species dynamic transcripts reveal the interaction mechanisms between Chrysanthemum morifolium and Alternaria alternata

“…The tangerine pathotype of A. alternata produces host-selective ACT-toxin, the biosynthesis of which is essentially encoded by a polyketide synthase gene that is also required for pathogenicity of this fungus [34]. NRPS and cytochrome P450 protein TES1 are required for tentoxin biosynthesis in A. alternata strain ZJ33 [35], while the PKS gene ACRTS2 is responsible for host-selective ACR-Toxin biosynthesis in the rough lemon pathotype of A. alternata [36]. In the present study, DEGs corresponding to NRPS and PKS homologs were also identified, confirming the importance of this toxin synthesis during A. alternata invasion into chrysanthemum.…”

Dual species dynamic transcripts reveal the interaction mechanisms between Chrysanthemum morifolium and Alternaria alternata

“…The tangerine pathotype of A. alternata produces host-selective ACT-toxin, the biosynthesis of which is essentially encoded by a polyketide synthase gene that is also required for pathogenicity of this fungus [33]. NRPS and cytochrome P450 protein TES1 are required for tentoxin (TEN) biosynthesis in A. alternata strain ZJ33 [34], while the PKS gene ACRTS2 is responsible for host-selective ACR-Toxin biosynthesis in the rough lemon pathotype of A. alternata [35]. In the present study, DEGs corresponding to NPRS and PKS homologs were also identi ed, con rming the importance of this toxin synthesis during A. alternata invasion into chrysanthemum.…”