Morphocultural and molecular characterization of Colletotrichum gloeosporioides isolates pathogenic to papaya.
Andrade E. M., Uesugi C. H., Ueno B., Ferreira M. A. S. V.
Author Affiliation: Departamento de Fitopatologia, Universidade de Brasília, CEP 70910-900, Brasília, DF, Brazil.
Fitopatologia Brasileira 32 : 21-31
Abstract : Twenty-nine monoconidial cultures of Colletotrichum isolated from pawpaw (Carica papaya) petioles and fruits were characterized based on conidial and appressoria morphology, colony colour, growth rate, sensitivity to benomyl, presence of setae, presence of the teleomorph, PCR with taxon-specific primers, and PCR-RFLP analysis of the ITS region. The 29 isolates from pawpaw were identified as C. gloeosporioides [Glomerella cingulata], based mainly on conidial and appressoria morphology. Most of the isolates produced cylindrical and/or obclavate conidia, and entirely or weakly lobed appressoria. The presence of setae, teleomorphic stage, colony colour, sensitivity to benomyl, and growth rate varied among the isolates and were affected by the culture medium. All the pawpaw isolates and 4 isolates (C. gloeosporioides and C. acutatum) from other hosts, i.e. mango (Mangifera indica), strawberry and apple (Malus domestica), were pathogenic on fruits of pawpaw cv. Sunrise Solo, producing similar symptoms, but varying in aggressiveness. PCR with C. gloeosporioides-specific primer, CgInt, confirmed the identity of the 4 pawpaw isolates. Two other isolates reacted with the C. acutatum-specific primer, CaInt2. The majority of the pawpaw isolates (23), however, did not react with any of the primers. The RFLP analysis of the amplified ITS region with RsaI generated distinct patterns that differentiated between the C. gloeosporioides and C. acutatum, and showed uniformity among the pawpaw isolates.