Biological roles and an evolutionary sketch of the GRF-GIF transcriptional complex in plants

Abstract

GROWTH-REGULATING FACTORs (GRFs) are sequence-specific DNA-binding transcription factors that regulate various aspects of plant growth and development. GRF proteins interact with a transcription cofactor, GRF-INTERACTING FACTOR (GIF), to form a functional transcriptional complex. For its activities, the GRF-GIF duo requires the SWITCH2/SUCROSE NONFERMENTING2 chromatin remodeling complex. One of the most conspicuous roles of the duo is conferring the meristematic potential on the proliferative and formative cells during organogenesis. GRF expression is post-transcriptionally down-regulated by microRNA396 (miR396), thus constructing the GRF-GIF-miR396 module and fine-tuning the duo’s action. Since the last comprehensive review articles were published over three years ago, many studies have added further insight into its action and elucidated new biological roles. The current review highlights recent advances in our understanding of how the GRF-GIF-miR396 module regulates plant growth and development. In addition, I revise the previous view on the evolutionary origin of the GRF gene family.

Overexpression of the Transcription Factor GROWTH-REGULATING FACTOR5 Improves Transformation of Dicot and Monocot Species

“…Similarly, the frequency of explants containing transgenic shoots significantly increased when GRF5 genes were transformed in sunflower, suggesting an effect on proliferation of transformed tissues ( Figure 6 ). The results obtained in these two crops are again consistent with the notion that GRF genes positively regulate cell division in growing plant organs ( Kim, 2019 ). Indeed, Arabidopsis plants overexpressing AtGRF5 develop enlarged leaves containing more cells, which was also accompanied with increased expression of cell cycle genes ( Horiguchi et al., 2005 ; Gonzalez et al., 2010 ; Debernardi et al., 2014 ).…”

“…Here, we report that ectopic expression of a developmental regulator, GROWTH-REGULATING FACTOR 5 ( GRF5 ), has a positive effect in boosting regeneration and genetic transformation in various crop species using established organogenic or embryogenic regeneration systems. The GRF genes belong to a small plant-specific transcription factor family and they form a transcriptional complex with GRF-INTERACTING FACTOR ( GIF ) to regulate plant growth and development by providing cues to primordial cells of vegetative and reproductive organs ( van der Knaap et al., 2000 ; Kim et al., 2003 ; Omidbakhshfard et al., 2015 ; Kim, 2019 ; Liebsch and Palatnik, 2020 ). Genetic analyses of plants with AtGRF5 overexpression and loss-of-function mutations in Arabidopsis revealed that this transcription factor is involved in the regulation of the cell division and expansion during leaf development ( Horiguchi et al., 2005 ; Horiguchi et al., 2006 ; Debernardi et al., 2014 ).…”

Genome-wide identification of GRF transcription factors in soybean and expression analysis of GmGRF family under shade stress

“…Furthermore, it has been shown that the microRNA miR396 directly inhibits the expression of GRFs through post-transcriptional regulation [11,14]. Constitutive overexpression of Arabidopsis miR396a and miR396b, or heterologous expression of ptc-miR396c (from Populus trichocarpa) and ath-miR396a (from Arabidopsis thaliana) in tobacco (Nicotiana tabacum) significantly reduce mRNA levels of GRFs and lead to narrower and smaller leaves, which mimic Arabidopsis grf1/2/3 [17][18][19][20]. Thus, the transcription levels of GRFs are regulated strictly and quantitatively by the miRNA-GRF-GIF cascade.…”

ORESARA15 Acts Synergistically with ANGUSTIFOLIA3 and Separately from AINTEGUMENTA to Promote Cell Proliferation during Leaf Growth

“…The an3-4 and ant-1 mutants were described previously [10,33]. an3-4 has large deletionsin transcribed regions of the AN3 (At5g26840) locus, which occurred by X-ray irradiation.…”

“…Another important cell proliferation regulator of organ growth, ANGUSTIFOLIA3/GRF-INTERACTING FACTOR1 (AN3/GIF1), is a member of the transcriptional coactivator family in Arabidopsis [8,9]. AN3/GIF1 is recruited by DNA-binding factors such as GROWTH REGULATOR FACTORs (GRFs) to activate target gene expression [10,11]. Mutations in GRF3, GRF4, or GRF5 have been shown to decrease cell proliferation activity, thereby reducing leaf size [12,13].…”