Effect of cuticular wax layers of green and red pepper fruits on infectionby Colletotrichum gloeosporioides

Colletotrichum gloeosporioides isolate KG13 caused necrotic, sunken anthrac nose symptoms on unwounded, wax-removed, and wounded green pepper fruits an d on wounded red fruits 7 days after inoculation. Hypersensitive reactions with small brownish discolorations, on some occasions, were found on unwoun ded red fruits. The isolate produced whitish symptoms with brown margins, b ut not the typical anthracnose on red fruits wax-removed by chloroform trea tment. Generally, wax-removed red fruits, but not green ones, produced larg er lesions and more conidia than untreated controls. Wounded pepper fruits had larger lesions than those with other treatments. More germinated conidi a, appressoria, and infection hyphae were found on wax-removed fruits than on controls; however? differences between green and red fruits were not fou nd. Cuticular wax layers of fruits were dissolved partially by chloroform a nd the outer epidermal cells were disrupted slightly. Anthracnose developme nt was negatively related with fruit developmental stage. Well-developed fr uits had more cuticular wax than less developed fruits. These results sugge st that the cuticular wax layers of pepper fruits may play a significant ro le in fruit infection by C. gloeosporioides isolate KG13, and mainly determ ine the incompatibility of red fruits to the isolate. Biochemical differenc es may also play a role.