The homeotic protein AGAMOUS controls late stamen development by regulating a jasmonate biosynthetic gene in Arabidopsis.
The Arabidopsis thaliana floral homeotic gene AGAMOUS (AG) plays a central role in reproductive organ (stamen and carpel) development. AG RNA is expressed in the center of floral primordia from a time prior to the initiation of stamen and carpel primordia until late in flower development. While early AG expression acts in specification of stamens and carpels, the role, if any, of continued AG expression in later flower development is unknown. To examine the timing of AG action and its possible late-stage functions, we performed a series of time-course experiments using a transgenic line with inducible AG activity in an ag homozygous mutant background. We show that AG controls late-stage stamen development, including anther morphogenesis and dehiscence, as well as filament formation and elongation. We further show that AG coordinates late stamen maturation by controlling a biosynthetic gene of the lipid-derived phytohormone jasmonic acid (JA). Expression analysis and in vivo binding of AG indicate that AG directly regulates the transcription of a catalytic enzyme of JA, DEFECTIVE IN ANTHER DEHISCENCE1. Our results indicate that stamen identity and differentiation control by AG is achieved by the regulation of different transcriptional cascades in different floral stages, with organ specification induced early, followed by phytohormone biosynthesis to coordinate stamen maturation.
Ito
Toshiro
T
Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore. itot@tll.org.sg
Ng
Kian-Hong
KH
Lim
Tze-Soo
TS
Yu
Hao
H
Meyerowitz
Elliot M
EM
D026342:AGAMOUS Protein, Arabidopsis / Q000378:metabolism*; D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000196:embryology* / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics; D002384:Catalysis / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D035264:Flowers / Q000196:embryology* / Q000201:enzymology / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D019787:Linoleic Acid / Q000494:pharmacology; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D010741:Phospholipases A / Q000235:genetics; D054466:Phospholipases A1 / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D026342:AGAMOUS Protein, Arabidopsis; D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; D012333:RNA, Messenger; C011006:jasmonic acid; D003907:Dexamethasone; C072239:methyl jasmonate; D019787:Linoleic Acid; C445094:DAD1 protein, Arabidopsis; D010741:Phospholipases A; D054466:Phospholipases A1