Early and Late Trisporoids Differentially Regulate β-Carotene Production and Gene Transcript Levels in the Mucoralean Fungi Blakeslea trispora and Mucor mucedo

Abstract

ABSTRACTThe multistep cleavage of carotenoids inMucoralesduring the sexual phase results in a cocktail of trisporic acid (C18) sex pheromones. We hypothesized that the C18trisporoid intermediates have a specific regulatory function for sex pheromone production and carotenogenesis that varies with genus/species and vegetative and sexual phases of their life cycles. Real-time quantitative PCR kinetics determined forBlakeslea trisporadisplayed a very high transcript turnover in the gene for carotenoid cleavage dioxygenase,tsp3, during the sexual phase. Anin vivoenzyme assay and chromatographic analysis led to the identification of β-apo-12′-carotenal as the first apocarotenoid involved in trisporic acid biosynthesis inB. trispora. Supplementation of C18trisporoids, namely D'orenone, methyl trisporate C, and trisporin C, increasedtsp3transcripts in the plus compared to minus partners. Interestingly, thetsp1gene, which is involved in trisporic acid biosynthesis, was downregulated compared totsp3irrespective of asexual or sexual phase. Only the minus partners of bothB. trisporaandMucor mucedohad enhanced β-carotene production after treatment with C20apocarotenoids, 15 different trisporoids, and their analogues. We conclude that the apocarotenoids and trisporoids influence gene transcription and metabolite production, depending upon the fungal strain, corresponding genus, and developmental phase, representing a “chemical dialect” during sexual communication.