The abscisic acid influence on the gene expression of pro- and anti-apoptotic proteins in the leaves of cucumber plants at low temperatures.

We studied the effect of abscisic acid (ABA) on the expression of genes encoding the functional homologues of proapoptotic (CsBAX) and antiapoptotic (CsBI-1) proteins in cucumber leaves at low temperatures. The exposure to a hardening temperature of 12°C caused a slight increase in the level of CsBAX gene transcript and a sharp increase in the CsBI-1 gene transcript. At a damaging temperature of 4°C, the content of the CsBAX gene mRNA significantly increased, whereas the content of the CsBI-1 gene mRNA remained virtually unchanged. The treatment of seedlings with ABA reduced the release of electrolytes from cells and both 12 and 4°C, i.e., increased the cold resistance and simultaneously decreased the level of CsBAX gene transcripts, but drastically increased the content of CsBI-1 gene mRNA.