NtWHY1 negatively regulates tobacco cold tolerance via interfering with flavonoid biosynthesis

Transcriptomic Analysis Reveals the Molecular Mechanisms Underlying Heat-Induced Suppression of Polymethoxyflavone Accumulation in Citrus Leaves

High-temperature stress impairs plant growth and alters secondary metabolism. Polymethoxyflavones (PMFs) are citrus-specific flavonoids with important nutritional benefits; however, their transcriptional responses to heat stress remain poorly understood. Here, five-month-old ‘Ponkan’ citrus seedlings were exposed to 40 °C for 6, 11, and 21 days. HPLC analysis showed that the accumulation of four major PMFs (sinensetin, nobiletin, tangeretin, and 5-demethylnobiletin) was significantly reduced in leaves under heat stress. RNA-seq identified 3424 differentially expressed genes shared across all three time points, which were enriched in pathways associated with microtubule cytoskeleton organization, cell cycle regulation, and glyoxylate and dicarboxylate metabolism. Further analysis of the PMF biosynthetic pathway revealed that 14 of 18 key structural genes, including CHS, CHI, FNSII, and OMT family members, were downregulated by heat treatment. In addition, several bHLH, AP2/EREBP, and MYB transcription factors, known regulators of flavonoid biosynthesis, exhibited expression patterns closely associated with PMF accumulation. RT-qPCR analysis validated the transcriptome results. Collectively, these findings suggest that heat stress suppresses PMF accumulation through coordinated repression of PMF biosynthetic genes and their potential regulators. This study provides new insights into the molecular basis of heat-responsive PMF metabolism and offers potential targets for maintaining citrus nutritional quality under elevated temperatures.

Transcription factor NtELF3 promotes the polyphenol accumulation by targeting NtFLS-1 and NtCHIL-2 genes in tobacco.

Tobacco (Nicotiana tabacum L.) is an important economic crop, from which polyphenols are crucial for regulating its growth and development as well as shaping its quality. However, few genes associated with polyphenol accumulation have been cloned from tobacco, and the molecular mechanisms underlying this process remain poorly understood. Here, we found that the tobacco transcription factor EARLY FLOWERING 3 (NtELF3), which is highly expressed in tobacco leaves, positively regulates the accumulation of chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, rutin, scopoletin, and total polyphenols in tobacco middle leaves. The metabolomic and transcriptomic analyses of middle leaves showed that a total of 177 differentially accumulated metabolites and 7409 differentially expressed genes (DEGs) were identified in ntelf3-1 mutant versus wild type, respectively. Further investigation identified that 17 DEGs were involved in phenylpropanoid metabolic and flavonoid metabolic processes. Combined analysis indicated that the phenylpropanoid and flavonoid biosynthesis pathways were also co-enriched in kyoto encyclopedia of genes and genomes enrichment analysis. Molecular biology experiment demonstrated that NtELF3 directly binds to the promoters of NtFLS-1 and NtCHIL-2 that are both associated with phenylpropanoid and flavonoid biosynthesis, and promotes their expression. Taken together, our results not only provide new theoretical support for in-depth understanding of the regulatory mechanisms underlying polyphenol accumulation in tobacco, but also offer excellent genes and germplasm resources for tobacco quality breeding.

Overexpression of PlPAT1, a GRAS transcription factor from Paeonia lactiflora, enhances salt stress tolerance in transgenic tobacco

It is demonstrated that PlPAT1 functions as a positive regulator of salt stress tolerance, likely through modulating osmotic balance and enhancing reactive oxygen species scavenging capacity.

Functional identification of the bHLH transcription factor MdSAT1 in response to Zn stress in apple

Functional characterization of the MdFLZ2 gene in drought and salt stress tolerance in apple.

Drought and salt stress are significant environmental limitations that severely constrain plant growth and productivity, therefore, enhancing stress tolerance is a key goal in crop improvement. The plant-specific FCS-like zinc finger (FLZ) proteins have been identified as important regulators of stress adaptation. In this study, we conducted a genome-wide characterization of the FLZ gene family in apple and functionally characterized MdFLZ2. qRT-PCR analysis revealed that MdFLZ2 was differentially expressed across various tissues and transcriptionally induced by both drought and salt stress. Subcellular localization assays demonstrated that the MdFLZ2 protein is localized to both the nucleus and the cytoplasm. The overexpression of MdFLZ2 in apple calli, Arabidopsis and tomato conferred increased resistance to drought and salt stress. In addition, yeast two-hybrid (Y2H) assays confirmed that MdFLZ2 interacted with MdSnRK1.1, and similar interactions were also detected between other MdFLZ family members and MdSnRK1.1. Collectively, our findings suggest MdFLZ2 as a positive regulator of drought and salt tolerance and highlight its potential to serve as a genetic resource for abiotic stress improvement.

MdXERICO negatively regulates salt tolerance in apple through ubiquitination and degradation of MdJAZ10.