Molecular cloning and characterization of OsCHR4, a rice chromatin-remodeling factor required for early chloroplast development in adaxial mesophyll. Zhao Chunfang,Xu Jiming,Chen Yue,Mao Chuanzao,Zhang Shelong,Bai Youhuang,Jiang Dean,Wu Ping Planta Mi-2 protein, the central component of the NuRD nucleosome remodeling and histone deacetylase complex, plays a role in transcriptional repression in animals. Mi-2-like genes have been reported in Arabidopsis, though their function in monocots remains largely unknown. In the present study, a rice Mi-2-like gene, OsCHR4 (Oryza sativa Chromatin Remodeling 4, LOC_Os07g03450), was cloned from a rice mutant with adaxial albino leaves. The Oschr4 mutant exhibited defective chloroplasts in adaxial mesophyll, but not in abaxial mesophyll. Ultrastructural observations indicated that proplastid growth and/or thylakoid membrane formation in adaxial mesophyll cells was blocked in the Oschr4 mutant. Subcellular localization revealed that OsCHR4::GFP fusion protein was targeted to the nuclei. OsCHR4 was mainly expressed in the root meristem, flower, vascular bundle, and mesophyll cells by promoter::GUS analysis in transgenic rice. The transcripts of some nuclear- and plastid-encoded genes required for early chloroplast development and photosynthesis were decreased in the adaxial albino mesophyll of the Oschr4 mutant. These observations provide evidence that OsCHR4, the rice Mi-2-like protein, plays an important role in early chloroplast development in adaxial mesophyll cells. The results increase our understanding of the molecular mechanism underlying tissue-specific chloroplast development in plants. 10.1007/s00425-012-1667-1

Rice Encoding a Component of the TAC Complex is Required for Chloroplast Development under Cold Stress. Lin Dongzhi,Zheng Kailun,Liu Zhaohui,Li Zhikang,Teng Sheng,Xu Jianlong,Dong Yanjun The plant genome Transcriptionally active chromosome (TAC) is a component of protein-DNA complexes with RNA polymerase activity, expressed in the plastid. However, the function of rice TAC proteins is still poorly understood. In this paper, we first report the identification of a new rice ( L.) mutant () in the gene encoding TAC. The mutant displayed an albino phenotype and malformed chloroplasts before the three-leaf stage when grown at low temperatures (20°C) and a normal phenotype at higher temperatures (>28°C). Map-based cloning revealed that encodes a novel chloroplast-targeted TAC protein in rice. In addition, the transcript levels of all examined plastid-encoded polymerase (PEP)-dependent genes were clearly downregulated in mutants at low temperatures, although partially recovering levels were obtained at high temperatures, comparable to wild-type plants. Furthermore, the transcripts were ubiquitously expressed in all examined tissues, with high expression levels in green tissues. The data suggest that the rice nuclear-encoded TAC protein TCM1 is essential for proper chloroplast development and maintaining PEP activity under cold stress. 10.3835/plantgenome2016.07.0065

Transposition behavior of nonautonomous a hAT superfamily transposon nDart in rice (Oryza sativa L.). Fujino Kenji,Sekiguchi Hiroshi Molecular genetics and genomics : MGG Transposable elements (TEs) have a significant impact on the evolution of gene function and genome structures. An endogenous nonautonomous transposable element nDart was discovered in an albino mutant that had an insertion in the Mg-protoporphyrin IX methyltransferase gene in rice. In this study, we elucidated the transposition behavior of nDart, the frequency of nDart transposition and characterized the footprint of nDart. Novel independent nDart insertions in backcrossed progenies were detected by DNA blotting analysis. In addition, germinal excision of nDart occurred at very low frequency compared with that of somatic excision, 0-13.3%, in the nDart1-4(3-2) and nDart1-A loci by a locus-specific PCR strategy. A total of 253 clones from somatic excision at five nDart loci in 10 varieties were determined. nDart rarely caused deletions beyond target site duplication (TSD). The footprint of nDart contained few transversions of nucleotides flanking to both sides of the TSD. The predominant footprint of nDart was an 8-bp addition. Precise excision of nDart was detected at a rate of only 2.2%, which occurred at two loci among the five loci examined. Furthermore, the results in this study revealed that a highly conserved mechanism of transposition is involved between maize Ac/Ds and rice Dart/nDart, which are two-component transposon systems of the hAT superfamily transposons in plant species. 10.1007/s00438-011-0633-0