GASA4, One of the 14-Member Arabidopsis GASA Family of Small Polypeptides, Regulates Flowering and Seed Development

Abstract

Members of the plant-specific gibberellic acid-stimulated Arabidopsis (GASA) gene family play roles in hormone response, defense and development. We have identified six new Arabidopsis GASA genes, bringing the total number of family members to 14. Here we show that these genes all encode small polypeptides that share the common structural features of an N-terminal putative signal sequence, a highly divergent intermediate region and a conserved 60 amino acid C-terminal domain containing 12 conserved cysteine residues. Analysis of promoter::GUS (beta-glucuronidase) transgenic plants representing six different GASA loci reveals that the promoters are activated in a variety of stage- and tissue-specific patterns during development, indicating that the GASA genes are involved in diverse processes. Characterization of GASA4 shows that the promoter is active in the shoot apex region, developing flowers and developing embryos. Phenotypic analyses of GASA4 loss-of-function and gain-of-function lines indicate that GASA4 regulates floral meristem identity and also positively affects both seed size and total seed yield.

One new kind of phytohormonal signaling integrator: Up-and-coming GASA family genes

“…11,13,15,19,20,27,44 GASA is an important plant hormone signal integrator involved in the regulation of seed germination, root growth, stem elongation, floral induction, flower organ development and other plant growth and development processes. Most of the GASA proteins are located in the cell wall, suggesting their function may relate to the cell wall extension or cell division.…”

“…In Arabidopsis, AtGASA4 not only involved in regulation the identification of floral meristem, promoting flowering and positive regulation of seeds size and yield, 11,20 but also accelerating seed germination by promoting GA signaling and inhibition of redox acivity. 22 Genetic analyses show that suppression of both AtGASA4 and AtGASA6 causes late flowering, while overexpression of AtGASA6 causes early flowering in Arabidopsis.…”

“…[9][10][11][12][13][14][15] GAST1 (GA-stimulated transcript 1) is the first GASA family gene member has been isolated and identified from tomato (Lycopersicon esculentum). 9 By far a great number of GASA genes and proteins have been isolated and identified from Petunia (Petunia hybrida), Arabidopsis (Arabidopsis thaliana), Potato (Solanum tuberosum) and rice (Oryza sativa) etc.. [13][14][15][16][17][18][19][20][21] GASA proteins play an important role in the regulation of plant growth and development, including participation in seed germination, 22,23 lateral root formation, 24,25 stem elongation, 18,26 flowering, 20,26 flower and fruit development, [27][28][29] biological and abiotic stresses responses, 12,13,[15][16][17]30,31 as well as the hormonal signal transduction. 9,14,15,31 The structure and function of this kind of proteins have a deeper understanding with different GASA members has been identified from a variety of plant species.…”

The bHLH Transcription Factor HBI1 Mediates the Trade-Off between Growth and Pathogen-Associated Molecular Pattern–Triggered Immunity inArabidopsis

“…These include about 31 cytochrome P450 genes, seven WRKY transcription factors, four VQ motifcontaining proteins, three U-box proteins, four calmodulin-like proteins, nine FAD binding Berberine family proteins, 11 glutathione S-transferases, and nine members of the 2-oxoglutarate and Fe(II)-dependent oxygenase superfamily (Supplemental Figure 1). In addition, HBI1 activates four (GASA3, 4, 6, and 7) and represses one (GASA5) of the 14 members of the GASA gene family (Roxrud et al, 2007), three of them are direct target genes of HBI1 (Supplemental Figure 1 and Supplemental Data Set 2). The GASA genes encode secreted Cys-rich proteins that have been implicated in development, stress response, and inhibiting ROS (Ko et al, 2007;Rubinovich and Weiss, 2010;Nahirñak et al, 2012;Sun et al, 2013).…”

Identification of floral genes for sex determination in Calamus palustris Griff. by using suppression subtractive hybridization

“…Another gibberellin-related gene that was found in the SSH library was giberellin-regulated protein 10, which belonged to the hormone-regulated gene family. The expression of this gene in flower buds may engage various biological processes such as germination, seed development, and flower induction (Roxrud et al, 2007).…”