Abstract
Chloroplast genes are transcribed by two types of RNA polymerase, termed NEP and PEP. PEP is eubacteria-type RNA polymerase, which is composed of plastid-encoded core subunits and one of nuclear-encoded sigma factors. In Arabidopsis thaliana, there are six sigma factors, SIG1 to SIG6. It is assumed that each sigma factor is involved in transcription of different plastid genes in response to both developmental and environmental signals. However, the roles of individual sigma factor in chloroplast transcription remain to be determined.
We are studying the function of sigma factors under stress conditions, and have already demonstrated that expression of SIG5 is induced by several environmental stresses. In this work, we found that expression of SIG6 is also, but specifically induced under low-temperature condition. In transposon-tagged sig6-2 mutant, growth inhibition and etiolation of leaves were observed after low-temperature treatment. Results including microarray analysis to identify low temperature-specific SIG6-dependent genes, will be reported.
