Abstract
Endosperm development in maize (Zea mays L.) and related cereals comprises a cell proliferation stage followed by a period of rapid growth coupled to endoreduplication. Regulation of the cell cycle in developing endosperm is poorly understood. We have characterized various subunits of cyclin-dependent kinase (CDK) complexes, master cell cycle regulators in all eukaryotes. A-, B-, and D-type cyclins as well as A- and B-type cyclin-dependent kinases were characterized with respect to their RNA and protein expression profiles. Two main patterns were identified: one showing expression throughout endosperm development, and another characterized by a sharp down-regulation with the onset of endoreduplication. Cyclin CYCB1;3 and CYCD2;1 proteins were distributed in the cytoplasm and nucleus of cells throughout the endosperm, while cyclin CYCD5 protein was localized in the cytoplasm of peripheral cells. CDKB1;1 expression was strongly associated with cell proliferation. Expression and cyclin-binding patterns suggested that CDKA;1 and CDKA;3 are at least partially redundant. The kinase activity associated with the cyclin CYCA1 was highest during the mitotic stage of development, while that associated with CYCB1;3, CYCD2;1 and CYCD5 peaked at the mitosis-to-endoreduplication transition. A-, B- and D-type cyclins were more resistant to proteasome-dependent degradation in endoreduplicating than in mitotic endosperm extracts. These results indicated that endosperm development is characterized by differential expression and activity of specific cyclins and CDKs, and suggested that endoreduplication is associated with reduced cyclin proteolysis via the ubiquitin–proteasome pathway.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-013-1990-1) contains supplementary material, which is available to authorized users.
Highlights
Maize (Zea mays L.) endosperm development is characterized by three distinct and successive types of cell cycle: acytokinetic mitosis, which produces a syncytium; mitotic cell division; and endoreduplication
These results revealed specificities in the spatiotemporal expression of different cyclins and cyclin-dependent kinase (CDK) and in the activity of cyclin/CDK complexes during endosperm development, and suggested that the transition from mitotic to endoreduplication cycles and its concomitant cell expansion are associated with reduced proteasome-dependent proteolysis of several types of cyclins
We searched Pioneer Hi-Bred’s and public databases to identify D, A- and B-type cyclins and A- and B-type CDKs potentially expressed during maize endosperm development
Summary
Maize (Zea mays L.) endosperm development is characterized by three distinct and successive types of cell cycle: acytokinetic mitosis, which produces a syncytium; mitotic cell division; and endoreduplication (reviewed by Sabelli and Larkins 2009a). By 8–10 DAP, initiating in central regions of the endosperm and extending toward its periphery, cells gradually and asynchronously cease dividing and engage in the endoreduplication cell cycle, which is characterized by repeated rounds of DNA replication without intervening sister chromatid segregation and cytokinesis (Edgar and Orr-Weaver 2001). This cell cycle variant results in highly polyploid cells with multiple, apparently uniform, copies of chromosomes. Endoreduplicated cells account for the major fraction of endosperm volume (Vilhar et al 2002)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
