GRAS, termed after GAI (gibberellic acid insensitive), RGA (repressor of GA1), and SCR (scarecrow), is a plant-specific transcription factor crucial for plant development and stress response. However, understanding of the functions played by the GRAS members and their target genes in citrus is limited. In this study, we identified a cold stress-responsive GRAS gene from Poncirus trifoliate, designated as PtrPAT1, by yeast one-hybrid library screening using the promoter of PtrBADH-l, a betaine aldehyde dehydrogenase (BADH)-like gene. PtrPAT1, belonging to the PAT1 subfamily, was localized in the nucleus and plasma membrane, exhibited transactivation activity and showed a remarkable upregulation under cold stress. Overexpression of PtrPAT1 elevated BADH activity, increased glycine betaine (GB) accumulation and conferred enhanced cold tolerance in transgenic tobacco plants compared with wild type, while downregulation in trifoliate orange by virus-induced gene silencing (VIGS) resulted in opposite trends. Furthermore, the activities of two antioxidant enzymes, including peroxidase (POD) and superoxide dismutase (SOD), were significantly increased in the overexpression plants, but remarkably decreased in the VIGS line, consistent with accumulation patterns of the reactive oxygen species (ROS). PtrPAT1 was demonstrated to interact with and activate the PtrBADH-l promoter through the putative PAT1-binding motif with the core sequence of TTTCATGT, indicating that PtrBADH-l is a target gene of PtrPAT1. Taken together, these results demonstrate that PtrPAT1 positively affects cold tolerance through the regulation of GB biosynthesis by modulating PtrBADH-l expression.

Peach trees exhibit vigorous growth that is often difficult to manage, frequently leading to canopy closure and the outward migration of fruiting positions, which ultimately results in diminished yield and fruit quality. Therefore, it is of great importance to study the key genes regulating peach tree vigor. Preliminary experiments identified PpNAC036 as a candidate gene potentially associated with vigor. In this study, we characterized the expression profile of PpNAC036 across various peach tissues. Our results demonstrate that PpNAC036 is most highly expressed in stems and responds rapidly to hormonal treatments, with expression levels increasing 3.6-fold and 3.9-fold under IAA and NPA treatments, respectively (5 min to 1 h). Subsequently, the PpNAC036 gene was cloned and overexpressed in Arabidopsis thaliana. Compared to the wild type, transgenic Arabidopsis exhibited a 28–50% reduction in primary root length and a 31.6–36.8% decrease in hypocotyl length. Conversely, at maturity, the transgenic Arabidopsis displayed enhanced vegetative vigor, with fresh and dry weights increasing by 37–48% and 29–46%, respectively. This growth was accompanied by a nearly two-fold increase in stem diameter and a 1.5- to 2-fold elevation in lignin content; simultaneously, genes related to lignin biosynthesis were upregulated. Hormonal profiling revealed that PpNAC036 overexpression led to a 7-fold increase in IAA, a 22–60% rise in GAs, and a 97–106% increase in CTKs, whereas ABA levels decreased by 5–6%. Furthermore, the transgenic Arabidopsis exhibited delayed germination and flowering, along with alterations in the number of floral organs. Transcriptomic analysis identified 2797 common DEGs, which were enriched in pathways related to cell wall organization and hormone signaling. Collectively, these findings elucidate the function of PpNAC036 as a pivotal regulator of plant vigor and secondary cell wall development, positioning it as a promising candidate gene for molecular breeding and architectural optimization in peach.

Organic acids are naturally present in plants and exert a positive influence on plant development, which justifies surveying their potential effect on adventitious root (AR) formation. In this study, 0.0298 mol/L (4000 mg/L) of malic acid and 0.0267 mol/L (4000 mg/L) of tartaric acid were used to explore the effects of low-molecular-weight organic acid on the rooting of persimmon rootstock Diospyros lotus L. during cutting propagation. After organic acid treatment, the rooting percentage and the survival rate significantly increased, accompanied by a greater development of lateral roots. Anatomical analysis revealed that Diospyros lotus L. exhibits characteristics that induce root primordia, and organic acid treatment can enhance the differentiation of root primordia. Furthermore, treatment with organic acid led to a substantial decrease in soluble sugar and starch contents, along with a slight increase in soluble protein content during early cutting stages. Additionally, the indole-3-acetic acid (IAA) content peaked in the early stages of AR formation and was significantly higher than that of the control, while abscisic acid (ABA) levels exhibited the opposite trend. Comparatively, gibberellic acid (GA₃) remained at extremely low levels throughout the rooting process in the organic acid groups compared to the control. In conclusion, the current study uncovers the anatomical structure over time during AR formation, revealing the dynamic changes in the related main nutrients and hormones and providing new ideas and a new practical approach for improving root regeneration in persimmon rootstock cuttings.