IMMUNODETECTION AND CHARACTERIZATION OF TOMATO ENDO-BETA-1,4-GLUCANASE CEL1 PROTEIN IN FLOWER ABSCISSION ZONES

Tomato (Lycopersicon esculentum Mill.) endo-beta-1,4-glucanase Cel1 mR NA accumulation was previously correlated with abscission of flower ex plants. Cel1 antibodies were raised against a fusion protein encoding a portion of the Cel1 polypeptide and was shown to react specifically with three polypeptides with molecular masses ranging between 51 and 5 3 kD in flower abscission zones induced to abscise. All three polypept ides were clearly suppressed in two transgenic lines expressing an ant isense Cel1 gene that specifically suppressed the accumulation of Cel1 mRNA, indicating that all three polypeptides are products of the Cel1 gene. Cel1 protein accumulation was correlated with flower abscission . Breakstrength and Cel1 protein content were also analyzed in flower explants, indicating that Cel1 protein accumulation is correlated with the final stages of flower shedding, which suggests that Cel1 is invo lved in the late stage of abscission. These results support the involv ement of Cel1 in the abscission of flower explants and suggest that ot her hydrolase activities also participate in that process.