These authors contributed equally to this work.
Impact of segmental chromosomal duplications on leaf size in the grandifolia-D mutants of Arabidopsis thaliana
Article first published online: 2 JUL 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 60, Issue 1, pages 122–133, October 2009
How to Cite
Horiguchi, G., Gonzalez, N., Beemster, G. T.S., Inzé, D. and Tsukaya, H. (2009), Impact of segmental chromosomal duplications on leaf size in the grandifolia-D mutants of Arabidopsis thaliana. The Plant Journal, 60: 122–133. doi: 10.1111/j.1365-313X.2009.03940.x
- Issue published online: 24 SEP 2009
- Article first published online: 2 JUL 2009
- Received 19 May 2009; accepted 22 May 2009; Published online 2 July 2009.
- segmental duplication;
- cell proliferation;
- leaf size
The number of cells in an organ is a major factor that specifies its size. However, the genetic basis of cell number determination is not well understood. To obtain insight into this genetic basis, three grandifolia-D (gra-D) mutants of Arabidopsis thaliana were characterized that developed huge leaves with two to three times more cells than the wild-type. Genetic and microarray analyses showed that a large segmental duplication had occurred in all the gra-D mutants, consisting of the lower part of chromosome 4. In the duplications, genes were found that encode AINTEGUMENTA (ANT), a factor that extends the duration of cell proliferation, and CYCD3;1, a G1/S cyclin. The expression levels of both genes increased and the duration of cell proliferation in the leaf primordia was extended in the gra-D mutants. Data obtained by RNAi-mediated knockdown of ANT expression suggested that ANT contributed to the huge-leaf phenotype, but that it was not the sole factor. Introduction of an extra genomic copy of CYCD3;1 into the wild-type partially mimicked the gra-D phenotype. Furthermore, combined elevated expression of ANT and CYCD3;1 enhanced cell proliferation in a cumulative fashion. These results indicate that the duration of cell proliferation in leaves is determined in part by the interaction of ANT and CYCD3;1, and also demonstrate the potential usefulness of duplication mutants in the elucidation of genetic relationships that are difficult to uncover by standard single-gene mutations or gain-of-function analysis. We also discuss the potential effect of chromosomal duplication on evolution of organ size.