Distribuição de mating-type em Fusarium decemcellulare Brick agente causal de superbrotamento em guaranazeiro (Paullinia cupana var. sorbilis H.B.K.)

Abstract

Fusarium decemcellulare is the main causal agent supersprouting in guarana, currently one of the major fungal diseases of culture in the State of Amazonas. Although considered free zone the disease years ago, in 2013 the disease was first detected in the State of Bahia, the main producer of guarana in Brazil. Depending the attacks area, supersprouting features three different symptoms: galls on stems, multiplication of vegetative buds or floral hypertrophy in inflorescences. Considered by many years a disease secondary and unimportant for the guarana crop, few studies have been conducted on this pathosystem the past 30 years. The analysis of distribution in MAT-1 and MAT-2 idiomorphs population is critical for the inference of the dynamics and potential of genetic variation of a pathogen and the degree of risk to the host. This work aimed to analyze the distribution of mating-type in F. decemcellulare and to estimate the effective number of the pathogen population in the main producing areas of guarana in the state of Amazonas. Of the different symptoms of supersprouting, 285 isolates were obtained and characterized. Of these, 165 presented the idiomorph MAT-1 and 120 MAT-2. Unlike other host species of F. decemcellulare, in guarana there was no occurrence of homothallic isolates and most producing cities of guarana analyzed had an effective population number over than 80%, showing a balance in the frequency of the idiomorphs MAT-1 and MAT- 2, suggesting the possibility of sexual reproduction in the field.