The Functional Significance of Leaf Shape Variation - Towards a Consensus from Gene to Community
Tsukaya, Hirokazu .
How leaf size and shape are controlled? –-- Genetic analyses of Arabidopsis mutants as an attempt to answer the question.
Isolation and characterization of Arabidopsis mutants with altered proportion of leaf shape has led us to identify four various types of genes that are involved in the proportional growth of leaf lamina (reviewed in Tsukaya 2006): AN, a member of CBA gene family, controls leaf width via the regulation of polar expansion of leaf cells; ROT3, a gene encoding a Brassinosteroid-biosynthesis enzyme, regulates leaf length via the control of polar cell elongation; AN3, a transcriptional co-activator, regulates the activity of plate meristem in leaf primordia; and ROT4, a member of a plant-specific peptide gene family, controls the number of cells in the longitudinal direction of the leaf. Most of these controls can be interpreted as cell-autonomous regulations, however, the case of the AN3 is a little bit different. Detailed analysis revealed that the loss-of-function an3 mutant shows “compensation”, a curious phenomenon in which significant reduction of cell number in leaf primordia triggers abnormal increase of cell volume (Tsukaya 2002; 2003). On the contrary, over-expression of AN3 simply increases the number of leaf cells without affecting their size.
Compensation seems to reflect an unknown, organ-wide interaction between cell cycling and cell expansion pathways. To reveal the nature of the linkage, we have conducted several genetic analyses, including construction of double mutants and tetraploid lines. Interestingly, we found that compensation is triggered only under a special set of conditions; the effect of tetraploidization on cell size differs among mutant and wild-type backgrounds. Based on these data, possible mechanisms of compensation, that reflects an organ-wide control system, will be discussed.
Tsukaya, H. (2002) Int. Rev. Cytol. 217: 1-39.
Tsukaya, H. (2003) Curr. Opin. Plant Biol. 6: 57-62.
Tsukaya H. (2006) Ann. Rev. Plant Biol. 57: 477-496.
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1 - The University of Tokyo, Graduate School of Science, Science Building #2, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Tokyo, 113-0033, Japan
Presentation Type: Symposium or Colloquium Presentation
Location: Williford B/Hilton
Date: Monday, July 9th, 2007
Time: 8:15 AM