GATA transcription factors have been demonstrated to play key regulatory roles in plant growth, development, and hormonal response. However, the knowledge concerning the evolution of GATA genes in Eucalyptus urophylla and their trans-regulatory interaction is indistinct. Phylogenetic analysis and study of conserved motifs, exon structures, and expression patterns resolved the evolutionary relationships of these GATA proteins. Phylogenetic analysis showed that EgrGATAs are broadly distributed in four subfamilies. Cis-element analysis of promoters revealed that EgrGATA genes respond to light and are influenced by multiple hormones and abiotic stresses. Transcriptome analysis revealed distinct temporal and spatial expression patterns of EgrGATA genes in various tissues of E. urophylla S.T.Blake, which was confirmed by real-time quantitative PCR (RT-qPCR). Further research revealed that EurGNC and EurCGA1 were localized in the nucleus, and EurGNC directly binds to the cis-element of the EurGUN5 promoter, implying its potential roles in the regulation of chlorophyll synthesis. This comprehensive study provides new insights into the evolution of GATAs and could help to improve the photosynthetic assimilation and vegetative growth of E. urophylla at the genetic level.

Poplar is an important fast-growing tree, and its photosynthetic capacity directly affects its vegetative growth. Stomatal density is closely related to photosynthetic capacity and growth characteristics in plants. Here, we isolated PagSTOMAGEN from the hybrid poplar (Populus alba × Populus glandulosa) clone 84K and investigated its biological function in vegetative growth. PagSTOMAGEN was expressed predominantly in young tissues and localized in the plasma membrane. Compared with wild-type 84K poplars, PagSTOMAGEN-overexpressing plants displayed an increased plant height, leaf area, internode number, basal diameter, biomass, IAA content, IPR content, and stomatal density. Higher stomatal density improved the net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and transpiration rate in transgenic poplar. The differential expression of genes related to stomatal development showed a diverged influence of PagSTOMAGEN at different stages of stomatal development. Finally, transcriptomic analysis showed that PagSTOMAGEN affected vegetative growth by affecting the expression of photosynthesis and plant hormone-related genes (such as SAUR75, PQL2, PSBX, ERF1, GNC, GRF5, and ARF11). Taken together, our data indicate that PagSTOMAGEN could positively regulate stomatal density and increase the photosynthetic rate and plant hormone content, thereby promoting vegetative growth in poplar. Our study is of great significance for understanding the relationship between stoma, photosynthesis, and yield breeding in poplar.

Poplar is an important afforestation and urban greening species. Poplar leaf development occurs in stages, from young to mature and then from mature to senescent; these are accompanied by various phenotypic and physiological changes. However, the associated transcriptional regulatory network is relatively unexplored. We first used principal component analysis to classify poplar leaves at different leaf positions into two stages: developmental maturity (the stage of maximum photosynthetic capacity); and the stage when photosynthetic capacity started to decline and gradually changed to senescence. The two stages were then further subdivided into five intervals by gene expression clustering analysis: young leaves, the period of cell genesis and functional differentiation (L1); young leaves, the period of development and initial formation of photosynthetic capacity (L3–L7); the period of maximum photosynthetic capacity of functional leaves (L9–L13); the period of decreasing photosynthetic capacity of functional leaves (L15–L27); and the period of senescent leaves (L29). Using a weighted co-expression gene network analysis of regulatory genes, high-resolution spatiotemporal transcriptional regulatory networks were constructed to reveal the core regulators that regulate leaf development. Spatiotemporal transcriptome data of poplar leaves revealed dynamic changes in genes and miRNAs during leaf development and identified several core regulators of leaf development, such as GRF5 and MYB5. This in-depth analysis of transcriptional regulation during leaf development provides a theoretical basis for exploring the biological basis of the transcriptional regulation of leaf development and the molecular design of breeding for delaying leaf senescence.

The MYB transcription factor family is one of the largest families of plant transcription factors (TFs), and it plays a vital role in the entire process of a plant’s growth and development. Well known in China, Eucommia ulmoides (E. ulmoides) produces a form of natural rubber called Eucommia ulmoides gum (EUG). Nevertheless, there is little research on the evolutionary history and expression patterns of its MYBs, as well as on the regulation of EUG by MYB TFs. This research provides a comprehensive description, classification, and potential functional analysis of the EuMYB gene family. A total of 119 MYB members of E. ulmoides were identified based on the whole genome sequencing data, and their gene structure, phylogenetics, chromosome location, conserved motifs, etc., were analyzed. Based on the phylogenetic tree results, EuMYBs could be divided into 35 sub-groups. In addition, chromosomal localization and collinearity analysis revealed the heterogeneous distribution of the MYB family in the E. ulmoides’ genome, indicating the expansion of its gene family. Moreover, promoter cis-acting elements showed that the promoter contained abundant light-responsive elements, anaerobic-induction-responsive elements, and abscisic-acid-responsive elements. A co-expression regulatory network between the EUG biosynthesis genes and the EuMYBs was built. Meanwhile, regarding the six EuMYBs with high expression in the gum-forming tissues selected that correlated with the farnesyl diphosphate synthase (FPS1) structural gene, RT-qPCR experiments showed a possible regulatory relationship between EuMYBs and FPS1, which played an important role in EUG biosynthesis. In conclusion, this paper defines a research gap and lays a foundation for further studies on the biological functions of EuMYBs.