DEVELOPMENTALLY-REGULATED EXPRESSION OF THE WOUND-RESPONSIVE AND PATHOGEN-RESPONSIVE TOMATO ANIONIC PEROXIDASE IN GREEN FRUITS

A highly anionic peroxidase (TAP) isolated from tomato was thought to be induced only upon wounding or fungal attack as this protein and its mRNA could not be detected in the vegetative tissues of healthy tomat o but accumulated to very high levels in tissues responding to woundin g or fungal attack. We now demonstrate a pattern of developmentally re gulated expression of the tap gene in the exocarp of green, but not re d, tomato fruits. Detaching green fruits from the vine, however, leads to the complete loss of the tap transcript within 72 h. Administratio n of various growth regulators through the pedicel of detached green f ruits revealed that cytokinin was able to sustain a level of tap trans cripts in 72 h detached fruits comparable with that found in fruits at tached to the vine. Wound-induced expression of tap was confined to th e healing periderm of green fruits but was not detectable in the wound -tissue of post-climacteric ripening fruits. These results suggest tha t the developmental and wound regulated expression of tap may occur by separate or overlapping signal transduction pathways. Treatment of to mato plants and green fruits with 2-chloro-ethylphosphonic acid (ethep hon) demonstrated that ethylene does not effect the developmental supp ression of tap in post-climacteric fruits, nor does it alter the norma l levels of tap transcripts in either healthy or wound-healing tomato tissues.