Caracterização morfológica, cultural, molecular e enzimática de isolados de Fusarium spp., de seringueira

Abstract

In the Brazilian forestry sector there are different cultures, such as eucalyptus, pine and rubber, grown as a business. Domestic production of dry rubber (derived from the rubber tree) rose more than eight times in 18 years, and reached 130 thousand tons in 2010. Domestic production is concentrated in São Paulo (57.8%), Bahia (14.05%) and Mato Grosso (11.53%). As in other plantation crops, heveiculture faces numerous problems such as diseases, including diseases of the leaves, trunk and panel. In the present work, the main goal was the study of Fusarium, whose symptoms begin in the cracks in the bark, from the rootstock, and goes towards the panel, causing the bark around the injury to dry up. Over time the lesion grows in size and the bark ends up shedding, making the tree unsuitable for bleeding. Specific goals were characterizing the obtained isolates and cognition of the genetic and pathogenic diversity of isolates from the major latex producing regions in Brazil, using for this: a) morphological and cultural characterization b) study of the aggressiveness of isolates c) test of clonal resistance d) effect of fungicides on in vitro control e) genetic characterization by sequencing genic regions with a taxonomic value, such as the ITS region and f) in vitro production of extracellular enzymes. In the collections of isolates and survey field data, there were some plots with 49.20% of pathological incidence of drought, with trees attacked in aggregates and the pathogen spreading more towards the planting row, the agent has been characterized at genus-level as Fusarium spp, a mitosporic fungus of theform- class Hyphomycetes, which produces conidia hyaline, septated in a canoe-like form, called macroconid, the disease has been named fusariose of rubber. The preferred temperature for the development of the pathogen is between 25 and 30 ° C. The sequences obtained from the ITS region has similarity to Fusarium decemcellulare. The isolates differentially responded to in vitro chemical control and the most efficient active ingredients for the three isolates were chlorothalonil + thiophanate methyl and tebuconazole. The tested isolates produce the extracellular enzymes: amylase, cellulase, protease (caseinase), laccase (oxidase), pectinase and catalase. However, the quantity produced of each enzyme is significantly different among the isolates, except for amylase. Through the inoculation tests it has been found that the isolates from São Paulo were the most aggressive and the most resistant clone was RRIM 600.