Common regulatory networks in leaf and fruit patterning revealed by mutations in the Arabidopsis ASYMMETRIC LEAVES1 gene.
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.
Alonso-Cantabrana
Hugo
H
División de Genética, Universidad Miguel Hernández, Campus de San Juan, Ctra. de Valencia s/n, 03550-San Juan de Alicante, Spain.
Ripoll
Juan José
JJ
Ochando
Isabel
I
Vera
Antonio
A
Ferrándiz
Cristina
C
Martínez-Laborda
Antonio
A
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D018398:Homeodomain Proteins / Q000378:metabolism; D026161:MADS Domain Proteins / Q000378:metabolism; D009154:Mutation; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D014157:Transcription Factors; C097414:AGL8 protein, Arabidopsis; C463739:AS2 protein, Arabidopsis; C456239:ASYMMETRIC LEAVES1 protein, Arabidopsis; C092213:KNAT2 protein, Arabidopsis; C491111:KNAT6 protein, Arabidopsis; C487569:RPL protein, Arabidopsis; D012097:Repressor Proteins