CYCD gene function in Arabidopsis seed development

Promoter-reporter (GUS) gene transgenics representing all ten CYCD genes were used to show that CYCDs are differentially expressed in flower, seed and vegetative tissues suggesting that they have discrete cell- and tissue-specific roles in plant development. CYCD 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 CYCDs reflected phylogenetic structure with characteristic overlapping expression patterns that could define each of the six or seven CYCD subgroups, suggesting both functional redundancy and functional specificity exists between members of the CYCD gene family in controlling cell division in these tissues. Genes belonging to the CYCD3, CYCD2/4 and CYCD6 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 CYCD2/4, CYCD5, and CYCD6 subgroups suggests they are involved in the development of the endosperm. The analysis of loss-of-function mutants for CYCD1;1, CYCD2;1/CYCD4;1, CYCD6;1 and CYCD7;1 showed that none of these genes are essential for normal seed development suggesting functional redundancy exists within the CYCD gene family. In contrast, loss of function of all three CYCD3 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 CYCD 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.EThOS - Electronic Theses Online ServiceGBUnited Kingdo