The Effect of 1-MCP on the Expression of Several Ripening-related Genes in Strawberries

To elucidate the role of ethylene in nonclimacteric fruit development and ripening, quantitative (cDNA-amplifled fragment length polymorphism) cDNA-AFLP was used to visualize differential gene expression in four stages of ripening of strawberries (Fragaria ×ananassa Duch. 'Elsanta') treated with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action. The proportion of clones affected by 1-MCP treatment was much higher in green than in white, pink, and red receptacle tissue. Three major cell-wall-related genes were affected by 1-MCP and, thus, are putatively ethylene dependent: a ripening-repressed beta-galactosidase (Faβgal3), up-regulated by 1-MCP; a putative endo-1,3-1,4-beta-D-glucanase (EGase), up-regulated in green and down-regulated in red fruit by 1-MCP; and a pectate lyase B (pIB), expressed only in the red stage and significantly down-regulated by 1-MCP. Furthermore, we have identified genes encoding an alcohol dehydrogenase, a protein kinase-related protein, and a putative glutathione S-transferase, all ripening-induced and down-regulated by 1-MCP, suggesting that their regulation is at least partly ethylene dependent.