Identification and expression profiling of SmGATA genes family involved in response to light and phytohormones in eggplant

Abstract

GATA proteins are transcription factors of zinc finger proteins, which play an important role in plant growth development and abiotic stress. However, there have been no identification or systematic studies of the GATA gene family in eggplant. In this study, 28 SmGATA genes were identified in the genome database of eggplant, which could be divided into four subgroups. Plant development, hormones, and stress-related cis-acting elements were identified in promoter regions of the SmGATA gene family. RT-qPCR indicated that 4 SmGATA genes displayed upregulated expressions during fruit developmental stage, whereas 2 SmGATA genes were down-regulated expression patterns. It was also demonstrated that SmGATA genes may be involved in light signals to regulate fruit anthocyanin biosynthesis. Furthermore, the expression patterns of SmGATA genes under ABA, GA and MeJA treatments showed that the SmGATAs were involved in the process of fruit ripening. Notably, SmGATA4 and SmGATA23 were highly correlated with the expression of anthocyanin biosynthesis genes, light-responsive genes, and genes that function in multiple hormone signaling pathways and the proteins they encoded were localized in the nucleus. All these results showed GATA genes likely play a major role in regulating fruit anthocyanin biosynthesis by integrating the light, ABA, GA and MeJA signaling pathways and provided references for further research on fruit quality in eggplant.

Keywords: GATA; Solanum melongena L.; gene family; hormones; light.

Figure 1

Phylogenetic analysis of GATA proteins in eggplant, tomato and Arabidopsis.

Figure 2

Phylogenetic tree, motif composition and gene structure of GATA genes in eggplant. (A) The phylogenetic tree is constructed by the full-length sequences of eggplant GATA proteins with 1000 replicates on each node. (B) The amino acid motifs (numbered 1-10) in SmGATAs are displayed in ten colored boxes, and black lines indicate protein sequence length. (C) Green rectangles, yellow rectangles lines represent the UTR (untranslated region), CDS (coding sequence or exons), respectively.

Figure 3

Schematic representations of the predicted regulatory elements in the SmGATA family.

Figure 4

Collinearity of GATA genes in eggplant. Colored lines indicate duplicated GATA gene pairs. The chromosome number is shown inside each chromosome.

Figure 5

Expression profiles of the eggplant SmGATA genes during fruit developmental.

Figure 6

Expression profiles of SmGATA genes in ‘Zaohongqie 2’ fruit following light induction via bag removal. (A) Colour changes of ‘Zaohongqie 2’ fruits after bag removal. (B) Hierarchical clustering of the expression profiles of 28 SmGATA genes after bag removing. (C) RT-qPCR analysis of 14 selected SmGATA genes following light induction. SmActin was used as the internal reference control to normalize template levels. The relative mRNA levels are represented as the mean ± SD (n=3). Statistically significant differences were assessed using Student’s t-test (*P < 0.05, **P < 0.01).

Figure 7

Expression profiles of eggplant GATA genes in response to ABA, GA, and MeJA treatment. SmActin was used as the internal reference control to normalize template levels. Relative mRNA levels are represented as the mean ± SD (n=3). Statistically significant differences were assessed using Student’s t-test (*P < 0.05, **P < 0.01).

Figure 8

Co-expression network analysis of GATA, anthocyanin biosynthesis, light signaling, and multiple hormone signaling genes in eggplant.

Figure 9

Subcellular localization of two GFP-fused SmGATA proteins. The two SmGATA-GFP fusion proteins (SmGATA4-GFP and SmGATA23-GFP) were transiently expressed in N. benthamiana leaves and observed by fluorescence microscopy 48 h later. Bar = 50 μm.