Members of the Fusarium solani species complex (fssc) associated with sudden death syndrome and red root rot of soybean in Brazil

Abstract

Brazil is the world's largest producer of soybeans. Two important diseases of this crop are sudden death syndrome (SDS) and red root rot (RRR). The causal agents of these diseases vary, but they are all members of the Fusarium solani Species Complex (FSSC), a diverse group of phylogenetic species that are pathogenic to several agricultural crops. While rootsymptoms are characterized by necrosis and tissue rot, in the leaves the development of chlorosis and interveinal necrosis is observed, resulting from the action of phytotoxins produced by the pathogen in the roots.This work is divided into 5 chapters. The first presents and characterizes the problem. The second presents the manuscript of the article “Five Fusarium solani species are associated with sudden death syndrome of soybean in Brazil”. In this work, we obtained 36 Fusarium isolates from different soybean-producing regions in Brazil and, through phylogenetic analysis, we showed that among these isolates we have representatives of 5 species from two FSSC Clades, namely F. paranaense, F. solani, F. brasiliense, F. crassistipitatum and F. tucumaniae. By performing a pathogenicity test, we confirmed that the representatives of the different Fusarium species, despite belonging to different FSSC Clades, are all pathogenic and induce similar foliar and root symptoms in soybean plants. In the thirdchapter, we present a project executed during the exchange at Purdue University - USA, where three vectors were successfully created for the genetic editing of F. virguliforme through the silencing of two genes (FvTox1 and FvNIS1) responsible for the encoding of two phytotoxins that induce the foliar symptoms of SDS. The activities described in the fourth chapter regarding the genetic transformation of F. virguliforme via ATMT were also carried out at Purdue University - USA. Finally, the fifth chapter refers to a project initiated abroad and completed at UFLA where the presence of FvTox1 and FvNIS1 in the genome of other FSSC member species was confirmed by PCR, which until then had only been identified in F. virguliforme.