Genome-Wide Identification and Expression Profiling of the GATA Gene Family Reveals Candidate Genes Associated with GA3-Induced Shoot Elongation in Citrus grandis ‘Wanbai’

Plant GATA transcription factors are zinc-finger proteins involved in signal transduction, growth and development. However, their potential involvement in plant height and gibberellin-associated shoot growth in pummelo insufficiently characterised. In this study, members of the CgGATA gene family were identified genome-wide and characterised through analyses of physicochemical properties, chromosomal distribution, phylogenetic relationships, gene structures, conserved motifs, collinearity and predicted cis-acting elements in putative upstream regulatory regions. RT-qPCR was used to examine expression profiles across sampled tissues, and expression changes associated with prolonged gibberellin (GA3) treatment in ‘Wanbai Pummelo’ shoot tips, and expression patterns in tall and dwarf pummelo genotypes. A total of 23 CgGATA genes were identified and classified into four phylogenetic subfamilies. Members of the same subfamily generally shared similar gene structures and conserved-motif compositions. Comparative collinearity analysis identified more syntenic GATA gene pairs between pummelo and sweet orange than between pummelo and Arabidopsis thaliana. The putative upstream regulatory regions contained predicted elements associated with light, phytohormone, growth and stress responses. The genes exhibited distinct expression profiles across the sampled tissues, with many showing relatively high within-gene values in stems and leaves. Prolonged GA3 treatment promoted seedling shoot elongation and was associated with changes in the transcript abundance of several CgGATA genes at 28 d. Integration of these expression profiles, the tall dwarf comparison and predicted gibberellin-responsive elements prioritised CgGATA11 and CgGATA18 as candidates for investigating plant height variation and shoot elongation in pummelo. These findings provide a basis for functional studies but do not establish that either gene directly regulates gibberellin signalling or plant height.