The Brazilian production of sugar-apple (Annona squamosa L.) predominates in the Northeast, being affected by anthracnose caused by Colletotrichum gloeosporioides. This study evaluated:1) the rates of micelial growth, conidiation, size of conidia and production of amylase, xylanase, protease and pectinases by the fungus isolated from lesions of avocado (Persea americana Mill), in different media; 2) the percentage of its germination and formation of appressoria on the young leaves of sugar apple; 3) the in vivo changes in levels of total proteins, phenols and soluble carbohydrates, before and after inoculation. Young leaves of two different ecotypes of sugar apple (PI and CT) were detached, inoculated and incubated either for their extraction (after 0 and 36 hours), or for its clearing (after 12, 18, 24, 30, 36, 42 and 46 hours), staining and analysis under the microscope. Each extract was partitioned against hexane, and the polar fraction was concentrated and re-solubilized for determination of biochemical parameters above mentioned. It was observed a higher sporulation of the fungal isolate in Mathur's medium, and it has produced all the enzymes tested in vitro. In vivo, this was more aggressive on the ecotype PI. There was ca. 80% germination and 50% of appressoria formation of the same after 24 and 30 hours of incubation on the ecotypes PI and CT respectively. The levels of total proteins, phenols and reducing glycids in extracts of CT were higher at 36 hours after inoculation, while only a slight increase in phenolic content was detected in extracts of PI.
Annona; Colletotrichum; sugar apple; anthracnose; biochemical resistance
