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.