Arabidopsis LEAFY COTYLEDON2 induces maturation traits and auxin activity: Implications for somatic embryogenesis.
LEAFY COTYLEDON2 (LEC2) is a central regulator of embryogenesis sufficient to induce somatic cells to form embryos when expressed ectopically. Here, we analyze the cellular processes induced by LEC2, a B3 domain transcription factor, that may underlie its ability to promote somatic embryogenesis. We show auxin-responsive genes are induced after LEC2 activation in seedlings. Genes encoding enzymes involved in auxin biosynthesis, YUC2 and YUC4, are activated within 1 h after induction of LEC2 activity, and YUC4 appears to be a direct transcriptional target of LEC2. We also show ectopic LEC2 expression induces accumulation of seed storage protein and oil bodies in vegetative and reproductive organs, events that normally occur during the maturation phase of embryogenesis. Furthermore, LEC2 activates seed protein genes before an increase in RNAs encoding LEC1 or FUS3 is observed. Thus, LEC2 causes rapid changes in auxin responses and induces cellular differentiation characteristic of the maturation phase. The relevance of these changes to the ability of LEC2 to promote somatic embryogenesis is discussed.
Stone
Sandra L
SL
Section of Plant Biology, College of Biological Sciences, and Graduate Program in Plant Biology, University of California, Davis, CA 95616, USA.
Braybrook
Siobhan A
SA
Paula
Stephanie L
SL
Kwong
Linda W
LW
Meuser
Jonathan
J
Pelletier
Julie
J
Hsieh
Tzung-Fu
TF
Fischer
Robert L
RL
Goldberg
Robert B
RB
Harada
John J
JJ
D017360:Arabidopsis / Q000196:embryology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics*; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers / Q000235:genetics; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D007210:Indoleacetic Acids / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*
D029681:Arabidopsis Proteins; D017931:DNA Primers; D007210:Indoleacetic Acids; C504240:LEC2 protein, Arabidopsis; D014157:Transcription Factors