Genome-Wide Comprehensive Analysis of the GASA Gene Family in Populus

Abstract

Gibberellic acid-stimulated Arabidopsis (GASA) proteins, as cysteine-rich peptides (CRPs), play roles in development and reproduction and biotic and abiotic stresses. Although the GASA gene family has been identified in plants, the knowledge about GASAs in Populus euphratica, the woody model plant for studying abiotic stress, remains limited. Here, we referenced the well-sequenced Populus trichocarpa genome, and identified the GASAs in the whole genome of P. euphratica and P. trichocarpa. 21 candidate genes in P. trichocarpa and 19 candidate genes in P. euphratica were identified and categorized into three subfamilies by phylogenetic analysis. Most GASAs with signal peptides were located extracellularly. The GASA genes in Populus have experienced multiple gene duplication events, especially in the subfamily A. The evolution of the subfamily A, with the largest number of members, can be attributed to whole-genome duplication (WGD) and tandem duplication (TD). Collinearity analysis showed that WGD genes played a leading role in the evolution of GASA genes subfamily B. The expression patterns of P. trichocarpa and P. euphratica were investigated using the PlantGenIE database and the real-time quantitative PCR (qRT-PCR), respectively. GASA genes in P. trichocarpa and P. euphratica were mainly expressed in young tissues and organs, and almost rarely expressed in mature leaves. GASA genes in P. euphratica leaves were also widely involved in hormone responses and drought stress responses. GUS activity assay showed that PeuGASA15 was widely present in various organs of the plant, especially in vascular bundles, and was induced by auxin and inhibited by mannitol dramatically. In summary, this present study provides a theoretical foundation for further research on the function of GASA genes in P. euphratica.

Genome-Wide Identification and Functional Analysis of the GASA Gene Family Responding to Multiple Stressors in Canavalia rosea

“…The CrGASAs were divided into three groups (G1, G2, and G3) based on their phylogenetic analysis with other species, including Arabidopsis, rice, and soybean ( Figure 2 ). According to this phylogenetic tree, most CrGASAs showed closer homology with soybean GASAs, and, as a diploid dicotyledon species, C. rosea holds more CrGASA members than that in the diploid monocotyledons—for example, 14 or 10 GASA members were found in maize and rice [ 28 , 32 ], while almost 20 GASA members were identified in apple (26), citrus (18), tobacco (18), and poplars (19 or 21), which probably indicates a slight GASA gene expansion in dicotyledon species [ 35 , 36 , 37 , 39 , 40 ]. Because of the relatively short protein lengths and the highly conserved GASA domains of all CrGASAs ( Figure 3 ), the classification of protein groups mostly depends on the variable N-terminus ( Figure 4 ), which also determines the subcellular localization of CrGASAs.…”

“…Poplar is an important tree species for shelterbelt and timber forests, and there are 21 candidate GASA s in Populus trichocarpa and 19 in Populus euphratica . Some members are widely involved in hormone responses, growth, and development for vegetative organs, and drought stress responses [ 36 , 37 ]. Grapevine ( Vitis vinifera ) is a major fruit crop, and the demand for seedless grapes is greatly increasing.…”

Transcriptome and Low-Affinity Sodium Transport Analysis Reveals Salt Tolerance Variations between Two Poplar Trees

“…GA2-oxidases (GA2oxs) regulate the deactivation of bioactive GAs and are very important to plant development and stress responses [ 54 ]. GASA ( Gibberellic Acid Stimulated in Arabidopsis ) genes encoding cysteine-rich peptides are involved in plant development and environmental adaption [ 55 ]. It has been reported that overexpression of GA2ox and GASA14 genes in Arabidopsis might enhance plants’ resistance to high salinity [ 56 , 57 ].…”

Genome-wide identification and characterization of the lettuce GASA family in response to abiotic stresses

“…5 ). Previous studies have revealed that the transcript of GASA from Populus euphratica is downregulated in leaves under MeJA treatment [ 33 ]. In Prunus mume, six GASA were upregulated after ABA treatment, and five GASA were upregulated at different time points after IAA treatment [ 34 ].…”