Abstract
The use of DNA sequences analysis has been an important mean to distinguish and to identify populations of organisms at different levels. By molecular markers several complex organisms have been successful detected in plants for distinct aims. Ribosomal DNA (rDNA) has been used to evaluate genetic variability, microorganism phylogeny and to develop specific primers for detection of plant pathogens in plant tissues. In this study, the objective was to characterize isolates of Colletotrichum gossypii var. cephalosporioides and Colletotrichum gossypii , collected in different regions of Brazil, by analyzing the nucleotide sequence of rDNA regions. ITS1, ITS2, and the intervening 5.8S gene were amplified by PCR and their sequences compared to each other and to those from other species registered in the GenBank. The rDNA of isolates associated with Gossypium spp. showed sequence identities ranging from 96 to 100% in the ITS1 region, 98 to 100% in the 5.8S gene, and 97 to 100% in the ITS2 region. The sequences were submitted to UPGMA analysis, and according to the phylogenetic trees, the C . gossypii var. cephalosporioides and C. gossypii species clustered together along with isolates of Glomerella cingulata from mango and papaya, and thus no distinction could be made between isolates of those organisms.
Highlights
Anthracnose and ramulosis, caused by the seed-transmitted fungi Colletotrichum gossypii South. and Colletotrichum gossypii var. cephalosporioides A
Because of the difficulties to associate C. gossypii var. cephalosporioides to different degrees of aggressiveness and expression of symptoms, efforts were directed to the genetic characterization of Colletotrichum spp. associated with cotton plants
Given the difficulties in distinguishing between the causal agents of cotton ramulosis and anthracnose, and the lack of information about their Ribosomal DNA (rDNA) ITS1 and ITS2 regions, the objective in the present work was to carry out the phylogenetic characterization of C. gossypii strains, considered to be the etiological agent of anthracnose, and of C. gossypii var. cephalosporioides strains, the etiological agent of ramulosis, from different geographic origins in Brazil
Summary
Anthracnose and ramulosis, caused by the seed-transmitted fungi Colletotrichum gossypii South. and Colletotrichum gossypii var. cephalosporioides A. Anthracnose and ramulosis, caused by the seed-transmitted fungi Colletotrichum gossypii South. S. Costa, respectively, are widespread diseases of cotton with high potential to severely reduce yields (LIMA et al, 1985; TANAKA, 1995). The amount of inoculum of both pathogens on cotton seeds influences the disease progress at variable levels of incidence and inoculum severity (ARAÚJO et al, 2006). The species C. gossypii, described by Southworth in 1890 (VIÉGAS, 1946), was subsequently reported by Arx (1957) as belonging to the C. gloeosporioides group, with Glomerella cingulata as the teleomorph. The cephalosporioides variety, the causal agent of ramulosis, reported by Costa and Fraga (1937) and described by Costa in 1946 (VIÉGAS, 1946), was first identified in the State of São Paulo, associated with the witch’s broom symptoms, which were not observed in the strains that cause anthracnose
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