Li Z, Li B, Shen WH, Huang H, Dong A

Leaf organogenesis occurs within the peripheral zone of the shoot apical meristem (SAM). Initiation and subsequent development of a leaf requires stable repression of a highly conserved class of plant genes, namely class-I KNOTTED1-like homeobox (KNOX) genes. In Arabidopsis, this class is comprised of four members: SHOOT MERISTEMLESS (STM), BREVIPEDICELLUS ...

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(BP), KNAT2 and KNAT6. Two transcription factors, ASYMMETRIC LEAVES1 (AS1) and AS2, are known to form a protein complex to repress BP, KNAT2 and KNAT6. Here we show that AS2 physically interacts with the microRNA319 (miR319)-regulated CINCINNATA-like TEOSINTE BRANCHED1-CYCLOIDEA-PCF (TCP) transcription factors in vitro and in vivo. By chromatin immunoprecipitation, we demonstrated that AS2 and TCPs bind to similar regions of the BP and KNAT2 promoters. In addition, DNA-binding activities of the TCP proteins rely on the presence of AS2, as the activities were dramatically reduced in the as2 mutant. The jaw-D mutant, which overexpresses MIR319a to downregulate several target TCP genes, strongly enhanced the as2 phenotypes and caused more severe ectopic expression of BP, KNAT2 and KNAT6. Our results reveal that KNOX repression requires different types of transcription factors that function together to ensure normal leaf development. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Date: Mar. 01, 2012

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