Comparative analysis of Pinus pinea and Pinus pinaster dehydrins under drought stress

Abstract

Maritime pine (Pinus pinaster) and stone pine (P. pinea) are two of the most drought-resistant Mediterranean trees. Several studies have analysed the response to drought stress at the molecular level in maritime pine, including the identification of drought-induced genes, transcriptomic analysis during dehydration or in-depth characterisation and diversity studies of specific candidate genes. On the contrary, much less information is available for stone pine, and notwithstanding being a closely related species, significant differences in the transcription profile of several genes during drought, evaluated using microarrays, were reported recently for these two species. In this study, we focus on P. pinea dehydrins, one of the most important gene families expressed in response to drought. We have identified eight dehydrin genes in P. pinea, orthologous to the ones previously described in P. pinaster, and have compared their transcription profiles under drought stress. For this purpose, we imposed a severe and prolonged drought treatment to P. pinea seedlings and analysed the expression pattern of proteins from the dehydrin family in needles, stems and roots. The complete open reading frames of these genes were amplified from cDNA and genomic DNA, and their intron/exon structures were determined. qRT-PCR was performed to analyse their expression pattern in needles, stems and roots during the drought treatment. Remarkable differences between the two species have been detected in the transcript patterns of five out of the eight genes, which could be related with the different behaviours described for these species under drought stress