Abstract

Drought is the most significant factor reducing plant productivity. To further study the stress-induced adaptive mechanisms of alfalfa at the molecular level, a drought-induced suppression subtractive hybridization (SSH) cDNA library was constructed. Initially, 225Escherichia coli colonies were obtained. By removing the vector sequences and the sequences with poor quality, 94 expressed sequence tags (EST) were retained. No significant homology to any previously identified genes was observed in 39 ESTs, whereas the remaining 55 ESTs showed high homology with plant genes of known and unknown functions registered in databases. Semi-quantitative real-time PCR analysis of five genes randomly selected in this SSH cDNA library of alfafa revealed that all of their transcripts were up-regulated after drought induction. Several ESTs identified from our drought-induced SSH of alfalfa were found to respond not only to drought but also high salinity and low temperature. This suggests that there may be a connection between the expression-regulation of gene and different environmental stresses in plants.

Key words: Suppression subtractive hybridization (SSH), Medicago sativa, drought stress, semi-quantitative real-time PCR (sqRT-PCR).