Isolation of cold-responsive genes from garlic, Allium sativum

Cold stress discourages development of the full genetic potential of plants and results in serious adverse effects on plant growth and limits agricultural productivity. Garlic (Allium sativum) requires low temperatures for the induction of flowering and bulb development. However, low or freezing temperatures can often cause physiological damage. Cold-responsive genes were isolated from a Korean garlic variety through systematic analyses using differential display (DD)-PCR, reverse transcription (RT)-PCR, and quantitative (Q)-PCR. Of the 2470 transcripts observed, 76 transcripts were up-regulated and 20 transcripts were down-regulated in response to cold temperatures (4°C) as determined by DD-PCR analysis. The differentially-expressed genes were further narrowed to 15 up-regulated and four down-regulated genes through subsequent RT-PCR and Q-PCR analyses. Of the 15 up-regulated genes, 11 genes were homologous to previously-reported abiotic-stress regulated genes in other species, and four genes did not match any known genes. Of the four down-regulated genes, three genes matched function-annotated genes and one gene did not match any genein the BLAST analysis. While most of the up-regulated poly-peptides were hydrophilic, the down-regulated polypeptides were neutral or hydrophobic. Of the 19 differentially-regulated genes, four genes showed different expression profiles in different tissues upon cold stress. Genetic manipulation of the CR genes obtained may provide molecular tool for overcoming frost damage of the garlic plants during hibernation.