Os01g0805600

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Annotated Information

Function

"Fig. 1 The suppression of Orysa;CycB1;1 produces aberrant rice seeds. a Mature seeds of wild type (WT), Pubi::GUS (CK), Pubi::CycB1;1OE (OE) and Pubi::CycB1;1RNAi transgenic (TL3 and TL4) rice. TL transgenic line. Arrows indicate the embryos; b CK and TL4-II seeds at diVerent development stages; c statistical analysis of the 1,000 kernel weights of WT, CK, OE, TL4-I and TL4-II seeds; d expression analysis of Orysa;CycB1;1 in TL4-I and TL4-II seedlings; e RT-PCR analysis of Orysa;CycB1;1 in Pubi::CycB1;1RNAi and Pubi::CycB1;1OE transgenic rice plants. Bar 2.6 mm (a), 3.0 mm (b)"

The cell cycle is an important process during seed development in plants and its progression is driven by a number of core regulators such as the cyclins. Currently, however, little is known regarding the role of the cyclins in embryo and endosperm development in cereals. In current study, we show that the knockdown of Orysa;CycB1;1 in rice results in the production of abnormal seeds, which at maturity contain only an enlarged embryo. It was further found that a delayed and abnormal cellularization occurred in the endosperm in these knockdown seeds which eventually became abortive. Moreover, the observed development of the enlarged embryo was also morphologically abnormal and found to be caused by an enlarged cell size rather than an increased cell number. Expression analysis showed that Orysa;CycB1;1 transcripts were localized in the endosperm and embryo. Genome-wide transcriptional profiling further indicated that a large number of genes are responsible for the phenotype of the enlarged embryo. The results of the knockdown of Orysa;CycB1;1 via an endosperm or an embryo-specific promoter also suggest that the enlarged embryo may be correlated to the abortive endosperm. The results suggest that Orysa;CycB1;1 expression is critical for endosperm formation via the regulation of mitotic division, and that the endosperm plays an important role in maintenance of embryo development in rice.(Fig.1)

Expression

B-type cyclins play key roles in the mitotic cell cycle and endoreduplication. Our previous study showed that knockdown of Orysa;CycB1;1 resulted in abnormal seeds and low seed production. To investigate the functions of Btype cyclins in plant reproductive growth, the research analyzed the ploidy of the abnormal Pubi::CycB1;1RNAi embryo. The results showed that the abnormal Pubi::CycB1;1RNAi embryo was triploid. The triploid seedlings had larger reproductive organs than those of control plants, and were abortive. Semi-quantitative RT-PCR and in situ hybridization analyses showed that Orysa;CycB1;1 transcripts were localized in cells of anthers and ovaries. This indicated that Orysa;CycB1;1 is critical for reproductive growth and might be involved in gametogenesis in rice. The results of this study increase our understanding of the functions of B-type cyclins in rice reproductive growth.

"Fig. 2. Aberrant rice seeds produced by Pubi::CycB1;1RNAi transgenic plants. "

"Fig. 3. Expression of Orysa;CycB1;1 in rice plants."

(Fig.2;Fig.3)

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Labs working on this gene

• Rice Functional Genomics, Joint Laboratory of Temasek Life Sciences Laboratory of Singapore
• Institute of Genetics and Developmental Biology, The Chinese Academy of Sciences,Beijing, China
• Rice Functional Genomics Group, Temasek Life Science Laboratory, 1 Research Link, The National University of Singapore, Singapore
• Institut de Biotechnologie des Plantes, UMR 8618, Universit´e Paris-Sud, Bâtiment 630, 91405 Orsay Cedex, France
• Department of Plant Genetics(VIB), Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
• Institute of Biotechnology, Tennis Court Road, CB2 1QT Cambridge, UK

References

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