Terfezia claveryi MAT locus characterization uncovers evolutionary insights about sexual reproduction of Pezizomycetes and reveals mating type dynamics in mycorrhizal plants.

Abstract

Terfezia claveryi is a hypogeous fungus that forms desert truffles through ectendomycorrhizal symbiosis with Cistaceae plants in arid and semiarid environments. The study presented herein elucidates the organization and structure of the mating type (MAT) locus in this species and the spatio-temporal dynamics of T. claveryi strains in Helianthemum almeriense mycorrhizal plants and soil from nursery to field. MAT genes are the master loci controlling sexual reproduction and development in fungi. Our findings demonstrate that T. claveryi is a haploid and heterothallic species as its strains harbor and express either TcMAT1-1-1 or TcMAT1-2-1 genes as revealed by genome sequencing and RNAseq analyses. DNA-binding motifs located in their respective promoter regions appear to play a major role in the regulation of reproductive processes. The α-box and HMG-box domains are highly conserved along the Pezizomycetes and their strong structural similarity despite its poor sequence similarity supports a common evolutionary origin. Moreover, we set out a PCR-based approach to monitor the dynamics of T. claveryi strains of opposite mating type on mycorrhizal plants and soil. T. claveryi mycorrhizal plants at the nursery stage presented strains of both mating types, whereas a notable dominance of strains with the TcMAT1-1-1 gene was observed in field stage. Altogether, this research provides insights about genetic regulation and evolution of the MAT locus within the Pezizomycetes, and the reproductive biology of this important desert truffle, along with reliable markers to track the spatio-temporal distribution of strains of opposite mating types.