Low temperature limits the growth and ornamental value of evergreen shrubs. Rhododendron yedoense var. poukhanense, an important ornamental shrub from Northeast China, frequently suffers freezing damage during winter. While exogenous abscisic acid (ABA) enhances cold tolerance in many plants, its molecular mechanisms at subzero temperatures remain poorly understood in non-model species lacking chromosome-level reference genomes. This study investigated the effects of exogenous ABA on freezing tolerance in R. yedoense var. poukhanense at -4 °C using an integrated physiological, transcriptomic, and proteomic approach. Cutting seedlings were subjected to four treatments: CK (22°C control), A (22°C + ABA), LT (-4°C), and ALT (-4°C + ABA). Photosynthetic pigments, osmotic regulation substances, antioxidant enzyme activities, and malondialdehyde (MDA) content were measured. Transcriptome sequencing and quantitative proteomics were performed, and transcriptome data were validated by quantitative real-time PCR (qRT-PCR) of 15 selected genes. ABA pretreatment reduced visible cold injury severity, partially preserved photosynthetic pigments, decreased MDA content by 28.7%, and promoted recovery of catalase (+43.6%), superoxide dismutase (+31.1%), and peroxidase (+20.0%) activities under freezing stress. Transcriptome analysis revealed 8, 444 differentially expressed genes (DEGs) in LT versus CK and 6, 481 DEGs in ALT versus CK, representing a 23% reduction in transcriptional reprogramming scope attributable to ABA priming. The ALT versus LT comparison identified only 1, 690 additional DEGs, indicating that most cold-responsive genes were pre-activated during the ABA priming phase. Proteome analysis identified 1, 461 differentially expressed proteins (DEPs) in ALT versus CK. Integrated analysis revealed extensive post-transcriptional regulation, with transcript-protein concordance of only 1.0-4.1%, and co-enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in both omics layers. qRT-PCR validation confirmed high reliability of the transcriptome data (R2 = 0.8500). These findings demonstrate that exogenous ABA enhances freezing tolerance through multi-layered molecular regulation encompassing transcriptional buffering, translational reprogramming, and functional reallocation from photosynthesis to stress protection. This study provides the first integrated physiology-transcriptome-proteome framework for ABA-mediated freezing tolerance in an evergreen ornamental shrub and offers theoretical support for ABA-based winter protection strategies.
Riwen Fei, Jia-Yi Liu, Si-Yu Duan et al.· Frontiers in Plant Science· 0 citations
The mesophyll protoplast transient expression system is an essential and robust methodology for examining gene expression regulation. Despite its potential, it has not been effectively employed to elucidate the genetic regulatory pathways and networks underlying plant responses to nutrient starvation, such as those involving phosphorus (Pi) and iron (Fe). In this study, we identified differentially expressed genes in response to Pi starvation in Arabidopsis using transcriptome analysis and RT-qPCR validation. Our findings revealed that Pi starvation significantly upregulated the expression of Pi-starvation induced (PSI) genes, including SPX1, SPX3, IPS1, and PS2, while simultaneously downregulating the expression of Fe starvation-responsive genes, such as FIT, IRT1, and FRO2. Additionally, through a dual luciferase transient expression assay in mesophyll protoplasts, we demonstrated that the transcription factor PHR1 serves as a crucial transcriptional regulator, modulating the expression of phosphate starvation response (PSR) genes. This regulation significantly enhances the transcriptional activity of the SPX1, SPX2, SPX3, IPS1, PS2, and PHT1;4 promoters. Upon the addition of the SPX1 protein, the activation of these gene promoters by PHR1 were alleviated. Concurrently, the transcriptional regulator FIT, which governs the expression of genes responsive to Fe starvation, markedly increased the transcriptional activity of the IRT1 and FRO2 promoters. Based on these findings, we propose the mesophyll protoplast transient expression system as a rapid and reliable method for investigating complex genetic networks. Overall, our study provides substantial evidence for understanding the role of the mesophyll protoplast transient expression system in elucidating the genetic regulatory pathways and networks involved in plant responses to nutrient starvation.
Yashan Tian, Jian-Ju She, Jin-Hui Lin et al.· Frontiers in Plant Science· 0 citations
Cadmium (Cd), a highly toxic and mobile heavy metal, has emerged as a severe environmental concern in global agroecosystems, posing a substantial threat to human health. Although prior studies have established that ZAT6 and ZAT10 positively regulate Arabidopsis tolerance to Cd toxicity, the underlying molecular mechanisms remain largely elusive. The present study provides evidence that a class I TCP transcription factor, TCP9, significantly enhances Arabidopsis tolerance to Cd toxicity through the direct activation of ZAT6 and ZAT10 expression. The real-time quantitative PCR (RT-qPCR) analysis indicates that the expression of TCP9 was induced under Cd toxicity. Meanwhile, the tcp9 mutant exhibited heightened sensitivity to Cd toxicity, accompanied by elevated Cd accumulation in both shoots and roots. Notably, the complemented lines exhibited phenotypic characteristics analogous to those observed in the wild-type (WT) plants. Further physiological and biochemical analyses revealed that, in comparison to WT, the tcp9 mutant displayed elevated hydrogen peroxide (H2O2) accumulation and reduced contents of catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) under Cd toxicity. Furthermore, TCP9 directly interacted with the promoters of ZAT6 and ZAT10 in vitro, facilitating their transcription and consequently enhancing plant tolerance to Cd toxicity. Overall, our findings showed that TCP9 enhances Cd tolerance via modulating ZAT6 and ZAT10, thereby identifying TCP9 as a potential key target for improving plant tolerance to Cd toxicity.
Jianju She, Feng Chen, Jia-Yi Liu et al.· Plants· 0 citations
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