Abstract
In higher plants, sigma factors of PEP(plastid-encoded RNA polymerase) of plastids are encoded by nuclear genes, and regulate plastid developments and proliferation. In Arabidopsis and rice, six sigma factors (SIG1~SIG6)were identified and their functions were analyzed. To clarify the function of sigma factor in a crop plant, soybean, we amplified genes of sigma factors from the genomic DNA with degenerate primers, and could obtain SIG5-like gene fragments. Further amplification of the cDNA and Southern blot analysis reveals the existence of at least two isoforms of Sig5 homologues in soybean (GmSIG5A,5B). SIG5 is involved in the stress response in Arabidopsis and rice. We here analyzed GmSIG5A, 5B genes for the tissue-specificity, stress- and light-responses of the expression. Some computer programs predict that SIG5A is localized in mitochondria and SIG5B in plastid, so we also did experiments to prove the assumption.
