REP-PCR, ultraestrutura de linhagens de Agaricus Bisporus e sua interação com Lecanicillium fungicola

Abstract

The Agaricus bisporus is the most appreciated and cultivated edible mushroom in the world. In Brazil, the productive sector has a wide range of strains from different origins. It makes hard to cultivate this mushroom due to the lack of important information such as genetic variability, and morphological and agronomical characteristics. Moreover, the parasites presence which lead to the diseases occurrence in the cultivation as the dry bubble disease caused by Lecanicillium fungicola have also hampered this mushroom production as well as caused great economic losses. Two studies were conducted involving this mushroom. On the first, fourteen A. bisporus strains were evaluated with Rep-PCR technique and electronic microscopy. The Rep-PCR technique allowed group the isolates according to their similarity. Using Scanning Electron Microscopy (SEM) it was possible to observe connection hyphae among basidia. It was also visualized, predominantly, two basidiospores per basidium, with occasional outbreaks of basidia with one, three and four basidiospores. Using Transmission Electron Microscopy (TEM), nuclei, vacuoles, lipid bodies and vesicles, besides reserve substances present in basidiospores were observed. The study shows that all Brazilian strains are belonging to the variety bisporus and they have a significant genetic variation may present peculiar characteristics. In the second study, was evaluated by SEM, the infection process of L. fungicola in three Brazilian strains of A. bisporus. The infection process of L. fungicola in three strains of A. bisporus was visualized both at vegetative phase and in basidiocarps formation phase. The micrographs demonstrate the strength of the vegetative mycelium to infection, having been observed the colonization process and reproduction of the parasite only in basidiocarps with formation of phialides, conidiophores and verticilos. The formation of calcium oxalate crystals using X-ray microanalyses both at the matching point of the hyphae in the plate as in the basidiocarps infection was also observed. These crystals can be related to the pathogenicity of L. fungicola. This is the first study that demonstrates the infection process of L. fungicola since the beginning of the formation of germ tubes (16 hours) to total tissue colonization (50 hours) in basidiocarps of A. bisporus.