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Morphological and physiological characterization of Colletotrichum sp. isolates from solanaceous crops

Anthracnose is a very frequent disease of solanaceous crops. The causal agent is reported as Colletotrichum gloeosporioides. In this work, Colletotrichum sp. isolates from hot pepper, sweet pepper and garden egg were characterized based on some of their morphological and physiological characteristics. Morphological characterization was based on the size and shape of conidia and the shape of the apressoria of 30 isolates. Physiological characterization was based on growth in different temperatures, use of different carbon sources and sensitivity to benomyl. Fifteen isolates were cultured on PDA under 10, 15, 20, 25, 28 and 30ºC. Use of carbon sources was achieved by culturing 32 isolates on minimal medium supplemented with glucose, fructose, lactose, maltose, sucrose or starch. To establish benomyl sensitivity, 43 isolates were cultured on PDA supplemented with 0, 1, 10 and 100 mug/mL of the fungicide. Garden egg isolates were less sensitive to benomyl and showed mainly fusiform conidia, with acute ends, similar to C. acutatum. Isolates from hot pepper and sweet pepper were highly sensitive to benomyl and showed mainly cylindrical conidia, with round ends, similar to C. gloeosporioides. Irregular, clavate or circular apressoria were observed in all isolates. Starch was the carbon source that led to the greater mycelial development of most isolates. The optimal temperature for almost all isolates was near to 25ºC, except for an isolate from hot pepper, which developed better at 28ºC. The mycelial growth rates of all isolates, for all tested temperatures, were similar to those showed by C. acutatum used as reference. The isolates collected from sweet pepper and hot pepper showed the greatest variability among the studied characteristics. Finally, it was shown that C. acutatum is also associated to anthracnose in solanaceous crops.

variability; Colletotrichum gloeosporioides; Colletotrichum acutatum; sweet pepper; hot pepper; garden egg


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