Investigation of the transcriptional response of sorghum to nitrogen resupply following growth under nitrogen‐limiting conditions provides new insight into the nitrogen‐responsive regulation of dhurrin in sorghum, highlighting candidate regulators for future functional characterization.
Abstract
Dhurrin, a cyanogenic glucoside, plays an important role in Sorghum bicolor physiology and defense. The concentration of dhurrin in sorghum is influenced by both nitrogen status and stage of plant organ development. While nitrogen resupply activates the expression of genes for dhurrin biosynthesis, the molecular mechanisms underlying this regulation remain unclear. In this study, we investigated the transcriptional response of sorghum to nitrogen resupply following growth under nitrogen‐limiting conditions. Using a time‐course design, we measured hydrogen cyanide potential (HCNp), growth, and nitrate content at 0‐, 2‐, 6‐, 12‐, 24‐, 36‐, 48‐, and 60‐h after resupply and collected tissue for RNAseq analysis in parallel for analysis of gene expression and construction of gene regulatory networks (GRNs). HCNp (mg g−1 DW) increased significantly in leaf and stem tissues following nitrogen resupply, with increases in the leaf partially driven by continued declines in controls under ongoing nitrogen stress. Expression of the dhurrin pathway genes was upregulated in leaves from 24 h after nitrogen resupply, with diel expression patterns observable over the remaining time points. No upregulation was observed in roots or stems, suggesting that developmental context overrides environmental cues. GRN analysis identified candidate transcription factors regulating dhurrin biosynthesis genes, including members of the MYB, bZIP, and GARP‐type transcription factor families. Some of these candidate transcription factors may be involved in relieving senescence‐associated suppression of dhurrin biosynthesis and link nitrogen signaling to pathway activation. These findings provide new insight into the nitrogen‐responsive regulation of dhurrin in sorghum, highlighting candidate regulators for future functional characterization.
ELONGATED HYPOCOTYL5 (HY5), a bZIP transcription factor, is a central regulator of light signalling and secondary metabolism, yet its role in coordinating primary metabolism with plant stress responses remains unclear. Here, we investigated HY5 function in Nicotiana tabacum using wild-type, HY5-overexpressing (NtHY5OX), and CRISPR/Cas9-generated HY5 knockout (NtHY5CR) lines. Integrated transcriptomic analyses of leaves and roots, combined with LC/MS- and GC/MS-based metabolite profiling, revealed that HY5 overexpression promotes a broad metabolic reprogramming characterised by enhanced expression of genes associated with the Calvin cycle, tricarboxylic acid (TCA) cycle, flavonoid biosynthesis, and nicotine metabolism. These transcriptional changes were accompanied by increased accumulation of phenolic compounds and alkaloids, indicating a shift in metabolic reprogramming toward defence-related specialised metabolism. In contrast, NtHY5CR mutants accumulated higher levels of amino acids, lipids, and organic acids, consistent with prioritisation of growth-associated primary metabolism at the expense of protective secondary metabolite production. Pathway enrichment analyses identified HY5 as a key regulatory node integrating central carbon metabolism with specialised metabolite biosynthesis. Functionally, this HY5-dependent metabolic configuration enhanced resistance to Alternaria solani and improved tolerance to salt stress, demonstrating that HY5-mediated metabolic plasticity underpins adaptive stress responses in tobacco. Together, these findings establish HY5 as a critical coordinator of metabolic and defence networks, providing mechanistic insight into how light-responsive transcriptional regulation shapes plant stress resilience and offering targets for engineering stress-tolerant crops.
Shambhavi Dwivedi, Deeksha Singh, Sanchita Gupta et al.· Plant, Cell and Environment· 0 citations
The results suggest that OsCYP51H9 participates in the phytosterol-BR pathway and plays a positive role in rice adaptation to low-nitrogen environments, providing a potential target for molecular breeding.
Zhengli Jiao, Jianyi Li, Weijuan Xu et al.· Plant physiology and biochem...· 0 citations
Magnesium (Mg) is fundamental for diverse physiological, biochemical, and molecular processes in higher plants because its deficiency or toxicity severely restricts development. The supply of Mg remodels the plant ionome and transporter profiles while simultaneously activating the nitrate reductase enzyme, which catalyzes nitrate reduction to nitrite and enhances nitrogen (N) assimilation. However, the specific mechanisms involving ion interactions and transporters in Mg metabolism that improve N metabolism in mulberry remain largely unexplored. To address this research gap, we employed physiological, transcriptomic, and functional characterizations of the nitrate reductase (NIA) gene in mulberry (Morus alba L. car. Yu-711) plants exposed to six Mg levels: deficiency at 0mM, low at 1mM, moderately low at 2mM, sufficiency (control, CK) at 3mM, toxicity at 6mM, and higher toxicity at 9mM for twenty days. Findings showed that Mg allocation follows an acropetal decrease, where roots retain the highest proportion followed by stems and leaves. Detailed correlation and regression analyses identified significant positive and negative interactions between Mg and other essential elements (N, K, P, S, Ca, Zn, Cu, and Fe), confirming that Mg supply alters the mulberry ionome. These alterations led to the induction of various transporters, coupled with upregulation of the NIA gene, which triggered activation of the N metabolism pathway. Functional characterization via virus-induced gene silencing (VIGS) of MaNIA resulted in a marked decrease in both Mg accumulation and NIA expression levels and subsequently reduced nitrate reductase (NR) enzyme activity. Subcellular localization studies further determined that NIA is localized in the cytoplasm. This research offers novel perspectives on the complex interplay between Mg and essential nutrients in the mulberry ionome and provides a critical framework for designing metabolic engineering strategies to optimize growth in plants suffering from Mg disorders.
Jianbin Li, Michael Ackah, F. K. Amoako et al.· Plant Science· 0 citations
This study provides a root-focused transcriptomic resource and identifies candidate regulatory genes potentially linking ABA-related responses with lignin/lignan-associated metabolism in H. pedunculosum under salt stress.
Yang Tao, Xiao Huang, Enhao Zhang et al.· Plant physiology and biochem...· 1 citation
These findings demonstrate that GmHMGR6 enhances soybean salt tolerance through coordinated regulation of nitrogen metabolism, nodulation, and photosynthetic performance.
ABSTRACT Strigolactones (SLs) modulate multiple aspects of plant development and stress physiology. This study investigated their role in maize response to abiotic stress by comparing an SL‐biosynthesis mutant (zmccd8) with wild‐type (WT) seedlings grown for 4 weeks in vermiculite under nutrient and water limitation. Plant growth, time‐course pigment accumulation, targeted gene expression, and root transcriptomic profiles were analyzed. Our results showed that zmccd8 plants were largely unable to induce leaf senescence and efficient nutrient remobilization toward younger tissues under nitrogen (N) deficiency, a response previously associated with maize adaptation to low N availability. In parallel, the mutant developed a smaller root system, mainly due to limited adventitious root formation, particularly under N shortage. Root transcriptomic profiling revealed that N deficiency strongly affected WT plants, inducing extensive regulation of pathways involved in nitrogen metabolism and transport, secondary metabolism, ethylene and MAPK signaling, oxidative stress responses, and major transcription factor families. These responses were largely absent in the zmccd8 mutant, suggesting reduced transcriptional plasticity and compromised capacity to cope with stress‐associated oxidative imbalance. Conversely, despite inducing substantial physiological and molecular responses, water stress elicited only modest SL‐dependent regulation, with limited and heterogeneous changes between genotypes. Overall, our findings demonstrate that in maize, SLs act in a stress‐specific manner, playing a predominant role in acclimatisation to nitrogen deficiency through coordinated regulation of senescence, nutrient remobilization, root architecture, and gene expression, while contributing more marginally to water‐stress acclimatisation. These results provide new insights into SLs' role in shaping maize physiological plasticity under abiotic stress conditions.
L. Buzzicotti, Claudia Camilletti, L. Ravazzolo et al.· Physiologia Plantarum : An I...· 0 citations
