植物の温度検知機構の分子生物学的解析

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1. Purpose: When plants are exposed to low-temperature, they introduce double bonds into fatty acids of membrane lipids, which compensates the decrease in molecular motion of membranes caused by low temperature. This phenomenon suggests that the plants can detect the change in temperature and transduce this signal to the expression of desaturase genes. The purpose of this research is to study the mode of temperature-induced regulation of desaturase expression in cyanobacteria.2. Results:(1) Genes (desA) for plant-type desaturases at the DELTA12 position were cloned from Synechocystis PCC6714 and Synechococcus PCC7002 with a probe derived from desA of Synechocystis PCC6803. When Synechococcus PCC7914, which is incapable of the DELTA12 desaturation, was transformed with these desA genes, this strain acquired the ability to introduce the double bond at the DELTA12 position. These observations confirm that the cloned genes were all desA.(2) The northern blot analysis of desA gene expression in Synechocystis PCC6803 demonstrated that the transcription of desA gene was markedly enhanced upon decrease in temperature.(3) A Promoter-detecting cassette constructed from the plasmid pBSDELTAAv was introduced into the genome of Synechocystis PCC6803. In a number of mutants produced some responded to temperature changes We are now identifying the temperature-responsible promoters.