A novel role for the floral homeotic gene APETALA2 during Arabidopsis fruit development.
The majority of the Arabidopsis fruit comprises an ovary with three primary tissue types: the valves, the replum and the valve margins. The valves, which are derived from the ovary walls, are separated along their entire length by the replum. The valve margin, which consists of a separation layer and a lignified layer, forms as a narrow stripe of cells at the valve-replum boundaries. The valve margin identity genes are expressed at the valve-replum boundary and are negatively regulated by FUL and RPL in the valves and replum, respectively. In ful rpl double mutants, the valve margin identity genes become ectopically expressed, and, as a result, the entire outer surface of the ovary takes on valve margin identity. We carried out a genetic screen in this sensitized genetic background and identified a suppressor mutation that restored replum development. Surprisingly, we found that the corresponding suppressor gene was AP2, a gene that is well known for its role in floral organ identity, but whose role in Arabidopsis fruit development had not been previously described. We found that AP2 acts to prevent replum overgrowth by negatively regulating BP and RPL, two genes that normally act to promote replum formation. We also determined that AP2 acts to prevent overgrowth of the valve margin by repressing valve margin identity gene expression. We have incorporated AP2 into the current genetic network controlling fruit development in Arabidopsis.
Division of Biological Sciences, Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
Juan José
JJ
Ripoll
Adrienne H K
AH
Roeder
Gary S
GS
Ditta
Martin F
MF
Yanofsky
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000166:cytology / Q000378:metabolism*; D005638:Fruit / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D012097:Repressor Proteins
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D009687:Nuclear Proteins; C097414:AGL8 protein, Arabidopsis; C499534:APETALA2 protein, Arabidopsis; C092212:KNAT1 protein, Arabidopsis; C487569:RPL protein, Arabidopsis; D012097:Repressor Proteins