Morphophysiological characterization and molecular identification of isolates of Guignardia citricarpa, a pathogenic agent of the citrus black spot - DOI: 10.4025/actasciagron.v30i5.5962

Abstract

The present work aims to identify 11 isolates of Guignardia citricarpa, the causal agent of the citrus black spot (CBS), obtained from affected fruit in different geographical regions, through PCR and morphophysiological characterization of propagative structures, sporing and mycelial growth in different means of culture, temperatures and photoperiods, under laboratory conditions. Through the PCR test, all isolates were identified as being the G. citricarpa pathogen. The characterized isolates were subjected to evaluations at temperatures of 20, 25 and 30^ºC, in continuous light, continuous darkness, and alternating 12 hours light and 12 hours darkness, during 24 days. The study used oat-agar (OA), potato-dextrose-agar (PDA) and carrot-dextrose-agar (CDA) as means of culture. The results showed an interaction between the different means of culture, temperatures and photoperiods. The mean of culture that best stimulated mycelial growth was CDA at 25ºC under the 12-hour photoperiod. The greatest spore (conidia) production was verified in PDA at 20^ºC in the 12-hour photoperiod. There was no sporing of any isolate in the CDA mean of culture. Under the 30^ºC temperature, the study verified only the production of hyphae and picnids in most isolates, in all means of culture and photoperiods.