Detection of ripening-induced cytochrome P-450 protein in various varieties of avaocado (Persea americana, Mill.)

The ripe Hass avocado contains one of the highest levels of the cytochrome P450 protein found in the plant kingdom. Therefore it has been used to prepare cytochrome P450 (P450) protein for analysis, and also provided the first cytochrome P450 gene to be cloned and sequenced from a plant source (Bozak et al. 1990). Polyclonal antibodies were generated against the CYP71A1 protein, and used in a western blot analysis of Hass fruit at various stages of ripening. An antigen of approximately 48,000 Daltons was absent in unripe fruit, but observed in ripening tissue. All of this work had been performed with the Hass variety. To determine whether other varieties of avocado grown on either the Cal Poly Pomona campus or at the Pine Tree Research Station (Santa Paula CA) contain similar levels of P450 protein, ripe tissue of the varieties Bacon, Zutano, Macarthur, Pinkerton, Fuerte, and Hass were subjected to Western Blot analysis. We determined that all six varieties contain similar levels of P450 protein, though the Hass variety contains the most. This indicates that CYP71A1 plays a role during ripening common to all these varieties. Therefore, it does not contribute to any characteristic of ripening which is unique to a single variety, such as flavor or skin color changes.