A cytochrome P450 gene is differentially expressed in compatible and incompatible interactions between pepper (Capsicum annuum) and the anthracnose fungus, Colletotrichum gloeosporioides

The anthracnose fungus, Colletotrichum gloeosporioides, was previously show n to have an incompatible interaction with ripe-red fruit of pepper (Capsic um annuum). However, the fungus had a compatible interaction with unripe-ma ture-green fruit. Using mRNA differential display, we isolated and characte rized a PepCYP gene expressed in the incompatible interaction, The PepCYP g ene encodes a protein homologous to cytochrome P450 proteins containing a h eme-binding domain. The expression level of PepCYP is higher in the incompa tible interaction than in the compatible interaction, and then remains elev ated in the incompatible interaction. In the compatible interaction, the ex pression of PepCYP is transient. The induction of PepCYP gene is up-regulat ed by wounding or jasmonic acid treatment during ripening. Analysis of PepC YP expression by in situ hybridization shows that the accumulation of PepCY P mRNA is localized in the epidermal cell layers, but not in the cortical c ell layers. An examination of transverse sections of the fruits inoculated with the fungus shows that the fungus invades and colonizes the epidermal c ell layers of the unripe fruit at 24 and 72 h after inoculation, respective ly but not those of the ripe fruit. These results suggest that the PepCYP g ene product plays a role in the defense mechanism when the fungus invades a nd colonizes the epidermal cells of fruits in the incompatible interaction during the early fungal infection process.