Comparative study between two strawberry pyruvate decarboxylase genes along fruit development and ripening, post-harvest and stress conditions

Abstract

Two strawberry cDNAs showing sequence similarity to pyruvate decarboxylase (PDC) genes ( Fapdc1 and Fapdc3 genes) from higher plants have been isolated by a differential display-PCR approach (DDRT-PCR). Sequence comparisons, northern and RT-PCR analysis showed that these strawberry genes are different and are expressed in a different expression pattern in vegetative tissues and in fruits during fruit development and ripening processes. RT-PCR studies indicated that only Fapdc1 gene is induced during fruit ripening whereas Fapdc3 gene is constitutively present in all tissues studied. The removal of the achenes from unripe green fruits induced the expression of Fapdc1 gene and this induction was inhibited by treatment of de-achened fruits with naphthaleneacetic acid (NAA) and indoleacetic acid (IAA), thus indicating that only the expression of Fapdc1 gene is under hormonal control. Also, Fapdc1 gene expression was increased in anoxia conditions in cultured cells. However, Fapdc3 is accumulated to high levels in strawberry cultured cells, irrespective of oxygen availability and probably controlled by sugar supply. The expression pattern of both genes in response to stress and post-harvest treatments is evaluated. All these results suggest that the strawberry Fapdc1 gene could play an important role in fruit ripening and aroma biogenesis, and also under stress conditions, whereas Fapdc3 would be involved in general metabolism to support energy production and biosynthesis of higher molecular weight compounds. The Fapdc1 genomic region has been cloned and characterised to isolate an inducible fruit ripening-related promoter for biotechnological purposes in strawberry.