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Impact of segmental chromosomal duplications on leaf size in the grandifolia‐D mutants of Arabidopsis thaliana
Author(s) -
Horiguchi Gorou,
Gonzalez Nathalie,
Beemster Gerrit T.S.,
Inzé Dirk,
Tsukaya Hirokazu
Publication year - 2009
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2009.03940.x
Subject(s) - arabidopsis thaliana , mutant , biology , arabidopsis , genetics , gene
Summary 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 G 1 /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.