title: OspTAC2 encodes a pentatricopeptide repeat protein and regulates rice chloroplast development.
abstract: Functional chloroplast generation depends on the precise coordination of gene expression between the plastid and the nucleus and is essential for plant growth and development. In this study, a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes was isolated from a60Co-irradiated rice population. The mutant gene was identified as an ortholog of the Arabidopsis plastid transcriptionally active chromosome protein 2 (pTAC2) gene, and the mutant strain was designated osptac2. Sequence and transcription analyses showed that OspTAC2 encodes a putative chloroplast protein consisting of 10 pentratricopeptide repeat (PPR) domains and a C-terminal small MutS-related (SMR) domain. Cytological observations via microscopy showed that the OspTAC2-green fluorescent fusion protein is localized in the chloroplasts. Transmission electron microscopy revealed that the chloroplast of the osptac2 mutant lacks an organized thylakoid membrane. The transcript levels of all investigated PEP (plastid-encoded RNA polymerase)-dependent genes were dramatically reduced in the osptac2 mutant, whereas the transcript levels of NEP (nuclear-encoded polymerase)-dependent genes were increased. These results suggest that OspTAC2 plays a critical role in chloroplast development and indicate that the molecular function of the OspTAC2 gene is conserved in rice and Arabidopsis.
authors.affiliation: Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. Electronic address: wangdk@mail.zaas.ac.cn.
authors.forename: Dekai
authors.initials: D
authors.lastname: Wang
authors.affiliation: Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Heqin
authors.initials: H
authors.lastname: Liu
authors.affiliation: Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Zhai
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, NY 14853-1801, USA.
authors.forename: Liangsheng
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Shao
authors.affiliation: Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Yuezhi
authors.initials: Y
authors.lastname: Tao
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D012275:Oryza / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D010940:Plant Proteins
keywords: Chloroplast development; Oryza sativa; Pentatricopeptide repeat protein