The INHIBITOR OF MERISTEM ACTIVITY (IMA) protein

Abstract

The INHIBITOR OF MERISTEM ACTIVITY (IMA) gene from tomato regulates the processes of flower and ovule development. IMA encodes a Mini Zinc Finger (MIF) protein that is characterized by a very short sequence containing an unusual zinc-finger domain. IMA acts as a repressor of WUSCHEL expression which controls the meristem organizing centre and the determinacy of the nucellus during ovule development. IMA inhibits cell proliferation during floral termination, controls the number of carpels during floral development and participates in the initiation of ovule primordia by activating D-type gene expression. In addition IMA is involved in a multiple hormonal signalling pathway like its Arabidopsis homolog MIF1. We thus propose that IMA, as a representative of this new family of zinc finger proteins, is an important effector in the regulatory pathway controlling meristem activity linking cell division, differentiation and hormonal control of development.

Addendum to: Sicard A, Petit J, Mouras A, Chevalier C, Hernould M. Meristem activity during flower and ovule development is controlled by the mini zinc finger gene INHIBITOR OF MERISTEM ACTIVITY in tomato. Plant J 2008; In press.

Figures and Tables

Figure 1 Tentative model for the function of IMA in the regulation of meristematic activity and flower determination. (A) IMA as a general inhibitor of plant growth linking hormonal perception and cell cycle control. (B) Promotion of meristem activity in the absence of IMA gene expression. (C) Inhibition of meristem activity by IMA. IMA prevents the perception of growth stimulatory hormonal signals, represses the expression of WUSCHEL and promotes D-type gene expression.

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