Os08g0163400

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RAP-DB:Os08g0163400 have an another name :OsSIG1..[1]

Annotated Information

Function

Sigma factors encoded by the nucleus of plants confer promoter specificity on the bacterial-type RNA polymerase in chloroplasts. We previously showed that transcripts of OsSIG1, which encodes one such sigma factor in rice, accumulate relatively late during leaf development. We have now isolated and characterized two allelic mutants of OsSIG1, in which OsSIG1 is disrupted by insertion of the retrotransposon Tos17, in order to characterize the functions of OsSIG1. The OsSIG1)/) plants were found to be fertile but they manifested an approximately one-third reduction in the chlorophyll content of mature leaves. Quantitative RT-PCR and northern blot analyses of chloroplast gene expression revealed that the abundance of transcripts derived from the psaA operon was markedly reduced in OsSIG1)/) plants compared with that in wild-type homozygotes. This effect was accompanied by a reduction in the abundance of the core protein complex (PsaA–PsaB) of photosystem I. Analysis of chlorophyll fluorescence also revealed a substantial reduction in the rate of electron transfer from photosystem II to photosystem I in the OsSIG1 mutants. Our results thus indicate that OsSIG1 plays an important role in the maintenance of photosynthetic activity in mature chloroplasts of rice by regulating expression of chloroplast genes for components of photosystem I..[2]

Expression

We isolated and characterized two rice nuclear genes, OsSIG2A and OsSIG2B, encoding the putative sigma-factor of the plastid RNA polymerase. Deduced protein sequences predicted a plastid-localizing signal in the N-terminus and subsequent polypeptides similar to known SIG2 proteins. Gene expression analysis revealed that the OsSIG2A transcript is more abundant than the OsSIG2B transcript in all tissues tested and that both rice SIG2s are expressed from earlier stages of leaf development than that in the case of OsSIG1. These results indicate differential expression of SIG genes in leaf morphogenesis, suggesting the existence of tissue- and stage-specific functions of SIG proteins for transcriptional regulation of chloroplast genes in plant development.[3]

We previously showed that the maximal level of OsSIG1 expression occurs at a later stage of leaf development than does that of OsSIG2A or OsSIG2B expression (Kasai et al., 2004). To characterize further the expression of OsSIG1, we performed northern analysis with total RNA isolated from three portions of the expanded leaves of 20-day-old Nipponbare (WT) plants. The amount of OsSIG1 mRNA was highest in the middle region of the leaf blades (Figure 2)[2]


Evolution

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Labs working on this gene

1 Cell-Free Science and Technology Research Center, Ehime University, Matsuyama 790-8577, Japan,

2 Experimental Farm, Kyoto University, Takatsuki, Osaka 569-0096, Japan,

3 The Venture Business Laboratory, Ehime University, Matsuyama 790-8577, Japan,

4 Department of Integrated Biosciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan,

5 Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0017, Japan,

6 National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan

References

  1. Kasai K , Kawagishi-Kobayashi M ., et al. (2004). "Differential expression of three plastidial sigma factors, OsSIG1, OsSIG2A, and OsSIG2B, during leaf development in rice.." Biosci Biotechnol Biochem 2004 Apr;68 (4):973-7.
  2. 2.0 2.1 Tozawa, Y, Masayoshi Teraishi., et al. (2007). "The plastid sigma factor SIG1 maintains photosystem I activity via regulated expression of the psaA operon in rice chloroplasts." The Plant Journal 52(1): 124-132.
  3. Cite error: Invalid <ref> tag; no text was provided for refs named ref3

Structured Information