Caracterização fisiológica de Colletotrichum gloeosporioides (Penz.) Penz. Sacc. associados a Mangifera indica L. em diferentes regimes de temperatura

Abstract

Mango (Mangifera indica L.) is a crop produced and exported by Brazil, however, it is frequently affected by several diseases, including anthracnose caused mainly by Colletotrichum gloeosporioides (Penz.) Penz. Sacc. Therefore, this work aimed to carry out the physiological characterization (mycelial growth, sporulation and germination) of C. gloeosporioides isolates, obtained from lesions in leaves of M. indica ‘Amrapali’. And for its development, six fungus isolates were reactivated, picked and placed in Petri dishes incubated at different temperatures (10°C, 15°C, 20°C, 25°C, 30°C e 35°C) in germination chambers BOD type with 12 h photoperiod. The evaluation of mycelial growth occurred at 2, 4, 6, 8 and 10 days after subculture, being carried out from the average of two diametrically opposite diameters, and the measurements were obtained with the aid of a digital caliper. On the tenth day of the radial growth assessment, the plates from this test were reused to account for the fungus sporulation, using a Neubauer plate and light microscope, where the spore count was performed in five quadrants of the chamber, for each board. To assess germination, plastic Petri dishes were used, containing agar-water medium, and a suspension of fungus spores was added to these plates, which was spread over the culture medium with the aid of a Drigalsky loop, then, the plates (one plate per isolate or treatment) were taken to BOD under the different temperatures. And to check germination, these plates were placed under a light microscope to visualize the conidia, where the length of the germ tube of five spores per plate was measured. After developing the experiments, it can be concluded that the isolates obtained were morphologically identified, confirming through the literature specialized to the species of C. gloeosporioides. In addition, all isolates had better mycelial growth and sporulation when exposed at 25°C, however, the fungal germ tube growth was higher at 35°C, with the highest germination percentage occurring at 35°C and 25°C, having 60% to 100% of conidia germination. It is also known that isolates M-09-01, M-09-02 and M-09-03 showed better results on mycelial growth, sporulation and germination, and for the last two physiological criteria mentioned, it is possible to realize a good performance also for the M-09-04. It is concluded that the fungus C. gloeosporioides presents a wide genetic variation, which allows a difference between its physiological and/or pathogenic actions, observed among its different isolates under study