JXB Advance Access originally published online on July 26, 2006
Journal of Experimental Botany 2006 57(12):3019-3031; doi:10.1093/jxb/erl063
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© 2006 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
Mutations in the RETICULATA gene dramatically alter internal architecture but have little effect on overall organ shape in Arabidopsis leaves
1División de Genética and Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, E-03202 Elche, Spain
2Plant Science Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
3School of Human and Life Sciences, Roehampton University, Holybourne Avenue, London SW15 4J, UK
4División de Genética, Universidad Miguel Hernández, Campus de San Juan, E-03550 Alicante, Spain
To whom correspondence should be addressed. E-mail: jlmicol{at}umh.es
A number of mutants have been described in Arabidopsis, whose leaf vascular network can be clearly distinguished as a green reticulation on a paler lamina. One of these reticulate mutants was named reticulata (re) by Rédei in 1964 and has been used for years as a classical genetic marker for linkage analysis. Seven recessive alleles of the RE gene were studied, at least four of which seem to be null. Contrary to many other leaf mutants studied in Arabidopsis, very little pleiotropy was observed in the external morphology of the re mutants, whose only aberration obvious at first sight is the reticulation exhibited by cotyledons and leaves. The re alleles caused a marked reduction in the density of mesophyll cells in interveinal regions of the leaf, which does not result from perturbed plastid development in specific cells, but rather from a dramatic change in internal leaf architecture. Loss of function of the RE gene seems to specifically perturb mesophyll cell division in the early stages of leaf organogenesis. The leaves of re mutants were nearly normal in shape in spite of their extremely reduced mesophyll cell density, suggesting that the epidermis plays a major role in regulating leaf shape in Arabidopsis. The RE gene was positionally cloned and found to be expressed in all the major organs studied. RE encodes a protein of unknown function and is identical to the LCD1 gene, which was identified based on the increased sensitivity to ozone caused by its mutant allele lcd1-1. Double mutant analyses suggest that RE acts in a developmental pathway that involves CUE1 but does not include DOV1.
Key words: Arabidopsis, leaf organogenesis, mesophyll development, reticulata