Article

Common regulatory networks in leaf and fruit patterning revealed by mutations in the Arabidopsis ASYMMETRIC LEAVES1 gene.

División de Genética, Universidad Miguel Hernández, Campus de San Juan, Ctra. de Valencia s/n, 03550-San Juan de Alicante, Spain.
Development (impact factor: 6.6). 08/2007; 134(14):2663-71. DOI:10.1242/dev.02864 pp.2663-71
Source: PubMed

ABSTRACT Carpels and leaves are evolutionarily related organs, as the former are thought to be modified leaves. Therefore, developmental pathways that play crucial roles in patterning both organs are presumably conserved. In leaf primordia of Arabidopsis thaliana, the ASYMMETRIC LEAVES1 (AS1) gene interacts with AS2 to repress the class I KNOTTED1-like homeobox (KNOX) genes BREVIPEDICELLUS (BP), KNAT2 and KNAT6, restricting the expression of these genes to the meristem. In this report, we describe how AS1, presumably in collaboration with AS2, patterns the Arabidopsis gynoecium by repressing BP, which is expressed in the replum and valve margin, interacts in the replum with REPLUMLESS (RPL), an essential gene for replum development, and positively regulates the expression of this gene. Misexpression of BP in the gynoecium causes an increase in replum size, while the valve width is slightly reduced, and enhances the effect of mutations in FRUITFULL (FUL), a gene with an important function in valve development. Altogether, these findings strongly suggest that BP plays a crucial role in replum development. We propose a model for pattern formation along the mediolateral axis of the ovary, whereby three domains (replum, valve margin and valve) are specified by the opposing gradients of two antagonistic factors, valve factors and replum factors, the class I KNOX genes working as the latter.

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Keywords

antagonistic factors
 
Arabidopsis gynoecium
 
Arabidopsis thaliana
 
crucial role
 
essential gene
 
FRUITFULL
 
gynoecium causes
 
mediolateral axis
 
opposing gradients
 
pattern formation
 
play crucial roles
 
replum development
 
replum factors
 
replum size
 
REPLUMLESS
 
repressing BP
 
valve development
 
valve factors
 
valve margin
 
valve width