The ArabidopsisGRF-INTERACTING FACTORGene Family Performs an Overlapping Function in Determining Organ Size as Well as Multiple Developmental Properties      

Abstract

Previously, the GRF-INTERACTING FACTOR1 (GIF1)/ANGUSTIFOLIA3 (AN3) transcription coactivator gene, a member of a small gene family comprising three genes, was characterized as a positive regulator of cell proliferation in lateral organs, such as leaves and flowers, of Arabidopsis (Arabidopsis thaliana). As yet, it remains unclear how GIF1/AN3 affects the cell proliferation process. In this study, we demonstrate that the other members of the GIF gene family, GIF2 and GIF3, are also required for cell proliferation and lateral organ growth, as gif1, gif2, and gif3 mutations cause a synergistic reduction in cell numbers, leading to small lateral organs. Furthermore, GIF1, GIF2, and GIF3 overexpression complemented a cell proliferation defect of the gif1 mutant and significantly increased lateral organ growth of wild-type plants as well, indicating that members of the GIF gene family are functionally redundant. Kinematic analysis on leaf growth revealed that the gif triple mutant as well as other strong gif mutants developed leaf primordia with fewer cells, which was due to the low rate of cell proliferation, eventually resulting in earlier exit from the proliferative phase of organ growth. The low proliferative activity of primordial leaves was accompanied by decreased expression of cell cycle-regulating genes, indicating that GIF genes may act upstream of cell cycle regulators. Analysis of gif double and triple mutants clarified a previously undescribed role of the GIF gene family: gif mutants had small vegetative shoot apical meristems, which was correlated with the development of small leaf primordia. gif triple mutants also displayed defective structures of floral organs. Taken together, our results suggest that the GIF gene family plays important roles in the control of cell proliferation via cell cycle regulation and in other developmental properties that are associated with shoot apical meristem function.

Arabidopsis GROWTH-REGULATING FACTOR7 Functions as a Transcriptional Repressor of Abscisic Acid– and Osmotic Stress–Responsive Genes, Including DREB2A

“…Thus, we propose that an interaction with an unknown cofactor through the QLQ domain is important for transcriptional repression by GRF7. The GRF1-interating factor family proteins described in previous reports Horiguchi et al, 2005;Lee et al, 2009) are candidates for such cofactors.…”

YUCCAGenes Are Expressed in Response to Leaf Adaxial-Abaxial Juxtaposition and Are Required for Leaf Margin Development

“…The histochemical detection of GUS activity was according to our previous methods (Li et al, 2005), with a staining incubation time of 6 h. The stained tissues were cleared as previously described when needed (Lee et al, 2009), and the microscopic images were obtained using a differential interference contrast microscope. Preparing plant material sections was as previously described (Xu and Shen, 2008).…”

Combined Large-Scale Phenotyping and Transcriptomics in Maize Reveals a Robust Growth Regulatory Network

“…For instance, leaves of maize (Zea mays) plants with altered levels of GA are affected in their growth rates, and the size of the division zone (DZ) is changed correspondingly . Examples in Arabidopsis of genes that are regulators of final leaf size by influencing cell proliferation are AVP1, JAW, and BRI1 (Gonzalez et al, 2010), GROWTH-REGULATING FACTOR1 (GRF1) and GRF2 (Kim and Kende, 2004), GRF5 (Horiguchi et al, 2005), DA1 and ENHANCER OF DA1 , ANGUSTIFOLIA3 (AN3)/GRF-INTERACTING FACTOR (Lee et al, 2009), and KLUH (Kazama et al, 2010). These examples illustrate that cell proliferation seems to be a key contributing factor to final leaf size.…”