Fast changes in expression of expansin gene and leaf extensibility in osmotically stressed maize plants

Adding PEG to the nutrient medium of maize (Zea mays L., hybrid Harkovskaya 310 MV) plants arrested the growth of their leaves initially but in 40–50 min growth resumed. This coincided with and was obviously due to a gradual increase in extensibility of the primary leaf suggested by changes in its extension rate, which was induced by adding a counterweight to inductive electromechanical position sensor. Specificity of gene probe for expansins was confirmed by sequencing cDNA and its comparison with literature data. Dot-blot analysis showed an increase in transcript level of expansin genes induced by PEG treatment. Thus gene-specific regulation of expansin mRNA pools likely contributes to fast adjustment of cell wall-loosening under conditions of water deficit.