Improvement of Strawberry Fruit Softening through the Silencing of Cell Wall Genes

摘要

To improve strawberry fruit shelf life, we have analyzed the effect of inhibiting the expression of several ripening-specific cell wall genes through antisense or RNAi transformation. The down-regulation of the genes FaplC and FaPG1 encoding a pectate lyase and a polygalacturonase enzyme, respectively, notably reduced the loss of firmness at the red ripe stage. Interestingly, PG-silenced plants showed firmer fruits than pectate lyase plants. In co transformation experiments with Agrobacterium strains carrying both genes, we found that several transgenic lines yielded firmer fruits than plants transformed with PG or pectate lyase alone, indicating a possible synergistic effect of both pectolytic enzymes on cell wall disassembly. Contrary to these results, the inhibition of the genes related to xyloglucan processing and/or depolymerization FaEG3 and FaExp2, encoding a β-1,4-glucanase and an expansin protein, respectively, did not modify fruit softening. A high number of FaExp2-silenced plants showed significant phenotypic alterations which could be related to the role of this gene in cell expansion. Currently, we are evaluating strawberry plants transformed with antisense sequences of a β-galactosidase and an acetyl pectin esterase gene, the product of both genes acting on the pectin matrix. Globally, our investigations show that it is possible to modify strawberry fruit softening through the inhibition of genes involved in pectin processing.