Antisense inhibition of pectin esterase gene expression in transgenic tomatoes

Summary Tomato plants (Lycopersicon esculentum Mill. cv. Ailsa Craig) were transformed with chimaeric pectin esterase (PE; EC 3.1.1.11) antisense RNA genes, based on a cDNA isolated from a tomato fruit library. PE enzyme activity in ripe fruit of these plants was reduced by up to 93%, as a result of inhibition of PE mRNA accumulation from an endogenous gene, or genes. No major differences in fruit development and ripening were apparent, although pectin remained more heavily esterified (methylated) at all stages of fruit development, thus confirming that PE has a role in pectin de-esterification in vivo. PE enzyme activity was unaffected in leaves or roots of the transformants, although antisense RNA transcripts were detected. This observation, and immunological differences between PE isoenzymes in leaves and roots compared to fruit, indicate differential expression of PE isoenzymes in these organs.