CYCD gene function in Arabidopsis seed development

• Main Author: Collins, C. C.
• Published: University of Cambridge 2008
• Subjects: 581.35
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597859

Promoter-reporter (<i>GUS</i>) gene transgenics representing all ten <i>CYCD </i>genes were used to show that <i>CYCD</i>s are differentially expressed in flower, seed and vegetative tissues suggesting that they have discrete cell- and tissue-specific roles in plant development. <i>CYCD </i>expression was tightly associated with cells with high cell division activity such as organ primordia and meristems, and in tissues known to retain a potential to divide, such as pericycle cells. In the embryo, endosperm and peripheral seed tissues, the domains of expression of the <i>CYCDs</i> reflected phylogenetic structure with characteristic overlapping expression patterns that could define each of the six or seven <i>CYCD </i>subgroups, suggesting both functional redundancy and functional specificity exists between members of the <i>CYCD </i>gene family in controlling cell division in these tissues. Genes belonging to the <i>CYCD3, CYCD2/4 </i>and <i>CYCD6</i> subgroups were strongly expressed throughout embryogenesis suggesting they have prominent roles in regulating cell divisions in the embryo, whereas the expression patterns observed for genes from the <i>CYCD2/4, CYCD5, </i>and <i>CYCD6 </i>subgroups suggests they are involved in the development of the endosperm. The analysis of loss-of-function mutants for <i>CYCD1;1, CYCD2;1/CYCD4;1, CYCD6;1 </i>and <i>CYCD7;1 </i>showed that none of these genes are essential for normal seed development suggesting functional redundancy exists within the <i>CYCD </i>gene family. In contrast, loss of function of all three <i>CYCD3</i> genes led to defects in the apical and central/basal regions of the embryo, resulting in an overall delay in developmental progression and seed abortion in severe cases. This study has also shown that <i>CYCD</i> genes may be used to manipulated important seed characteristics such as seed size, as a result of a promotion of cell division/growth in the embryo and endosperm.