Transcriptome analysis of alfalfa under cold and freezing stress
To investigate the potential target mRNAs, two degradome libraries from cold stress and freezing stress samples were constructed, as previously described. In brief, poly(A)-enriched RNA were isolated and ligated to an RNA oligo-nucleotide adaptor containing a 3’MmeI recognition site, and the ligated products were used to synthetize first-strand cDNA. Then a short PCR (five cycles) was employed to amplify the cDNA, and the product was ligated to a double-stranded DNA adaptor, and subjected to gel purification again for PCR amplification. The final cDNA library was purified and sequenced on Illumina GAII by BGI-Shenzhen Co. Ltd (Shenzhen, China).