Identification of low temperature inducible genes of Lactuca sativa by using suppression subtractive hybridization method

Abstract

Abstract Lettuce ( Lactuca sativa ) is one of important vegetables taken as raw state. It is expected to be kept as high quality under low temperature conditions, especially freezing state. However, there are few research regarding to its molecular response to abiotic stress of lettuce. As we reported previously, lettuce plants acquire low levels of freeze tolerance. In the present paper, we have isolated 192 cDNA clones corresponding to cold induced genes of lettuce plant by using a PCR-based suppression subtractive hybridization method. Most clones were categorized into 62 distinct known genes based on homology search. Out of the corresponding genes, 45 genes were confirmed to be low-temperature-inducible with reverse transcription-qPCR. Some of the genes encoded stress-related proteins, such as late embryogenesis abundant proteins including dehydrin, which were expected to be involved in enhancement of freezing tolerance. On the other hand, some of proteins encoded by genes were suspected to be involved in suppressing the enhancement of freezing tolerance, such as vacuolar processing enzyme (VPE), adagio protein, and gigantea-like protein. In particular, VPE have been reported to be associated with program cell death, suggesting that it is negatively involved in freezing tolerance of lettuce.