Sexual development of Stemphylium lycopersici.

MEDINA, ROCIO; FRANCO, MARIO; GAUNA, JUAN ; SAPARRAT, MARIO; BALATTI, PEDRO

Montevideo

Congreso; X Encuentro Latinoamericano y del Caribe de biotecnología agropecuaria y xi simposio REDBIO Argentina.; 2019

REDBIO

In filamentous ascomycetes, self-sterility, as well as fertility, depend on the mating-type (MAT)locus, whose genes code transcription factors, peptide pheromones, and their correspondingreceptors. Heterothallism (self-sterility) occurs between two fungal strains with compatiblemating types. On the contrary, homothallism refers to a self-fertile organism with a completesexual cycle. Heterothallic species are characterized by the presence in each isolate of onlyone idiomorph, either MAT1-1 or MAT1-2, while both types are present in homothallic species.While some Stemphylium species are homothallic others are heterothallic. The teleomorphicstate of Stemphylium phytopathogenic filamentous ascomycete fungi has not been describedyet. Here we identified the idiomorphs within a collection of isolates of S. lycopersici. A set ofspecific primers aimed at amplifying the MAT locus was design based on available sequencesof representatives of Stemphylium (AY335164.1, AY340940.1 and LGLR01000402.1-TW65_08925). Among 20 S. lycopersici isolates we found that each contained only oneidiomorph. While 85% belonged to the MAT1-1 type and the remaining 15% were of the Mat1-2 type. The isolates idiomorph were unrelated with the place and plant of isolation, suggestingthat in natural habitats the idiomorphs are together. The MAT1-1 idiomorph prevalence overMAT1-2 might explain why the teleomorphic state, has not been found yet. Future studies invitro might be performed to evaluate the occurrence of the sexual cycle of S. lycopersici.