Interação de Penicillium spp e Aspergillus flavus com sementes e grãos de milho e soja

Abstract

In the Brazil few studies have been conducted performed in relation to diversity, the transmission in the seeds and plants and to behavior of these speci es in stressful environments. The aim of this research was to identify the species of Penicillium in maize produced in some regions of Brazil. To evaluate the relation of the species Talaromyces wortimannii and Penicillium nov. sp on maize seeds. Studying the behavior of Penicillium polonicum and Aspergillus flavus isolates and the interaction of these species with maize and soybean grain. The phylogenetic analyzes based on the ITS, beta-tubulin and RPB2 genes were used for studing the diversity. In the effects of T. wortimanii and Penicillium sp nov. two contamination procedures of maize grain were used, and the results were evaluated used sanitary test (blotter method), germination, emergence speed index, fresh and dry height, and initial and final stand. To study the behavior of the isolated Penicillium polonicum and Aspergillus flavus, the fungi were grown on PDA medium, modified by solutes glycerol, mannitol and NaCl in three potential of water and different temperatures. After incubation period isolates were analyzed by mycelial growth rate and the production of conidia. The maize and soybeans grain were contaminated separately with each isolate, and storage in the same conditions of water stress and temperature. The contaminated and uncontaminated seeds were analyzed for water content and aflatoxins concentration. The 107 isolates collected were identified, among them species of Penicillium and Talaromyces and two new species. The incidence of the Talaromyces and Penicillium species was 100%, the high incidence of these species not affected the percentage of maize seed germination. Based on the results of IVE and initial and final of the stand observed a reduction of both in the potential of 96 hours. The increased of exposition period reduced the height and fresh weight of the plants. The highest incidence was in the maize stalk and the incidence of T. wortimannii was higher than the incidence of Penicillium nov. sp. In the study of the behavior and effect of Penicillium polonicum and Aspergillus flavus species observed that there was not inhibition of growth and production of conidiain any potential, being, that the greater mycelial growth in the potential of -1.0, -5,0 and - 10.0 Mpa and temperature of 20, 25 and 30 ° C. The same conditions of water stress and temperature provided the increase in water content of maize and soybean grain contaminated with Penicillium polonicum and Aspergillus flavus isolates and the high concentration of aflatoxin in grain contaminated with Aspergillus isolate.