Figure 4.

Accumulation of PG mRNA, enzyme activity, and protein during ripening of transgenic ACC synthase antisense tomato fruits. MG fruits were harvested and maintained under a constant flow of humidified air at 25°C for 28 d. During this period some fruit began to slowly ripen. The ripening stage of each fruit was determined (see Methods), and accumulation of PG mRNA, activity, and protein was analyzed in fruit that had attained a ripening stage defined by the physical state of the locule and seed maturity. A, mRNA-hybridization analysis. Each lane contained 3.2 μg of poly(A⁺) mRNA. B, PG enzyme assays were performed by incubating 10 mg of crude cell wall protein extracts with polygalacturonic acid, and PG activity was determined by a reducing sugar assay. C, Internal ethylene concentration (microliters/liter). D, Immunoblot of cell wall protein extracts. Each lane contained 10 mg of protein, and PG protein was detected with antibody by using a chemiluminescence kit. PG2 indicates the mobility of purified PG.