Soil salinization is a crucial factor that impacts plant distribution and growth. Apocynum venetum, an ornamental plant with medicinal value, has shown remarkable salt tolerance. However, the specific mechanisms through which A. venetum responds to salt stress are not yet fully understood. To address this gap, we conducted a study where 10-week-old A. venetum seedlings were subjected to salt stress by irrigating them with a nutrient solution containing varying concentrations of NaCl (0, 100, 200, and 350 mmol·L⁻¹). After the salt stress treatment, various growth indicators (such as plant height, root length, root fresh weight, root dry weight, leaf fresh weight, leaf dry weight, root water content, leaf water content, and root–leaf ratio) as well as physiological indicators (including SOD and CAT activities in both leaves and roots, soluble protein contents in leaves and roots, and chlorophyll and carotene contents in leaves) were determined. In addition, the gene expression profile of roots under salt stress was examined by transcriptome sequencing to explore the mechanism of salt response in A. venetum. Our results show that salt stress led to yellowing and wilting of A. venetum seedling leaves. Furthermore, the chlorophyll and carotenoid contents in the leaves of the 350 mmol·L⁻¹ NaCl-treated group were significantly reduced. Although the leaf and root biomass gradually decreased with an increase in the salt concentration, the root–leaf ratio exhibited a decreasing trend. NaCl stress also caused significant changes in physiological indices in the A. venntum leaves and roots. The activities of superoxide dismutase (SOD) and catalase (CAT) increased in both leaves and roots of the 100 mmol·L⁻¹ NaCl-treated group. The soluble protein content in both leaves and roots increased under the 200 mmol·L⁻¹ NaCl stress. To screen changes in root gene expression, transcriptome sequencing and qRT-PCR were performed. GO and KEGG enrichment analyses revealed that salt stress primarily affects carbohydrate metabolism, MAPK signaling transduction, phytohormone signaling pathways, glyoxylate and dicarboxylate metabolism, and other pathways. This study provides a novel understanding of the growth and physiological response of A. venetum leaf and root to NaCl stress, as well as the changes in the transcription levels in A. venetum root. The results serve as a reference for future research on salt-tolerant mechanisms and molecular breeding of A. venetum.

The Homeodomain leucine zipper (HD-Zip) family of transcription factors is crucial in helping plants adapt to environmental changes and promoting their growth and development. Despite research on the HD-Zip family in various plants, studies in Lagerstroemia (crape myrtle) have not been reported. This study aimed to address this gap by comprehensively analyzing the HD-Zip gene family in crape myrtle. This study identified 52 HD-Zip genes in the genome of Lagerstroemia indica, designated as LinHDZ1-LinHDZ52. These genes were distributed across 22 chromosomes and grouped into 4 clusters (HD-Zip I-IV) based on their phylogenetic relationships. Most gene structures and motifs within each cluster were conserved. Analysis of protein properties, gene structure, conserved motifs, and cis-acting regulatory elements revealed diverse roles of LinHDZs in various biological contexts. Examining the expression patterns of these 52 genes in 6 tissues (shoot apical meristem, tender shoot, and mature shoot) of non-dwarf and dwarf crape myrtles revealed that 2 LinHDZs (LinHDZ24 and LinHDZ14) and 2 LinHDZs (LinHDZ9 and LinHDZ35) were respectively upregulated in tender shoot of non-dwarf crape myrtles and tender and mature shoots of dwarf crape myrtles, which suggested the important roles of these genes in regulate the shoot development of Lagerstroemia. In addition, the expression levels of 2 LinHDZs (LinHDZ23 and LinHDZ34) were significantly upregulated in the shoot apical meristem of non-dwarf crape myrtle. These genes were identified as key candidates for regulating Lagerstroemia plant height. This study enhanced the understanding of the functions of HD-Zip family members in the growth and development processes of woody plants and provided a theoretical basis for further studies on the molecular mechanisms underlying Lagerstroemia plant height.

Background/Objectives: Teosinte branched1/Cycloidea/Proliferating cell nuclear antigen factors (TCPs) are plant-specific transcription factors involved in leaf development, flowering, branching, hormone signaling, and stress responses. Prunus a key temperate fruit tree with ornamental spring blooms, still lacks comprehensive TCP gene studies across many species. Methods: We identified 154 TCP genes in eight Prunus species: 19 in Prunus tenella var. tenella, 19 in P. amygdalus, 17 in P. armeniaca ‘Rojo Pasion’, 19 in P. mira, 20 in P. jamasakura var. jamasakura, 19 in P. fruticosa, 19 in P. mume var. tortuosa, and 22 in P. × yedoensis ‘Somei-yoshino’. These genes were classified into PCF, CIN, and CYC/TB1 groups. We examined segmental duplication, conserved motifs, and cis-acting elements. Expression patterns of 12 TCPs in P. tenella var. tenella were tested under low-temperature stress (25 °C, 5 °C, −5 °C, and −10 °C), and PtTCP9’s subcellular localization was determined. Results: TCP genes within the same groups showed similar motifs and cis-acting elements. Cold stress analysis identified multiple low-temperature-responsive elements in gene promoters. Four genes (PtTCP2, PtTCP6, PtTCP14, and PtTCP16) increased expression under cold stress, while six genes (PtTCP1, PtTCP5, PtTCP8, PtTCP9, PtTCP17, and PtTCP19) decreased. PtTCP9 was localized to the nucleus. Conclusions: This was the first genome-wide study of the TCP gene family in these eight Prunus species, providing valuable insights into the characteristics and functions of TCP genes within this important genus.

Transcription factors (TFs) in the homeodomain-leucine zipper (HD-ZIP) family serve as essential regulators of plant development and control responses to environmental stimuli. To date, however, the HD-ZIP gene family in Prunus nana remains to be fully characterized. Accordingly, a genome-wide analysis of P. nana HD-ZIP family genes was performed using the most recent genomic data available, leading to the classification of 30 HD-ZIP TFs. These genes were annotated and subjected to systematic analyses of phylogenetic relationships, protein physicochemical properties, sequence-based structural characteristics, chromosomal distributions, and associated cis-acting regulatory elements. High levels of diversity were observed with respect to the gene structures for these PnaHD-Zip genes and the cis-regulatory elements found in the promoter regions upstream of these genes, suggesting that they play diverse roles in a range of biological contexts. These 30 PnaHD-Zip genes were further classified into four subgroups based on the results of phylogenetic, gene structure, and conserved motif analyses. Subsequent qPCR analyses indicated that PnaHD-Zip1 and PnaHD-Zip7 expression levels tended to increase was continuously inhibited in response to cold stress, suggesting that proteins in this HD-ZIP gene family may exhibit distinct responses to low-temperature stress exposure. Overall, these results offer a robust foundation for future studies seeking to explore the functional roles that HD-ZIP TFs play as regulators of cold stress tolerance in P. nana, in addition to offering more general insight regarding the regulatory functions and characteristics of these different HD-ZIP genes in P. nana.