Plant, Cell & Environment最新文献

Circadian clocks execute temporal regulation of metabolism by modulating the timely expression of genes. Clock regulation of mRNA synthesis was envisioned as the primary driver of these daily rhythms. mRNA oscillations often do not concur with the downstream protein oscillations, revealing the importance to study protein oscillations. Chlamydomonas reinhardtii is a well-studied miniature plant model. We quantitatively probed the Chlamydomonas proteome for two subsequent circadian cycles using high throughput SWATH-DIA mass spectrometry. We quantified > 1000 proteins, half of which demonstrate circadian rhythms. Among these rhythmic proteins, > 90% peak around subjective midday or midnight. We uncovered key enzymes involved in Box C/D pathway, amino acid biosynthesis, fatty acid (FA) biosynthesis and peroxisomal β-oxidation of FAs are driven by the clock, which were undocumented from earlier transcriptomic studies. Proteins associated with key biological processes such as photosynthesis, redox, carbon fixation, glycolysis and TCA cycle show extreme temporal regulation. We conclude that circadian proteomics is required to complement transcriptomic studies to understand the complex clock regulation of organismal biology. We believe our study will not only refine and enrich the evaluation of temporal metabolic processes in C. reinhardtii but also provide a novel understanding of clock regulation across species.

Understanding plant adaptations in extreme environments is crucial, as these adaptations often confer advantages for survival. However, a significant gap exists regarding the genetic mechanisms underlying these adaptations and their responses to human-induced rapid environmental change (HIREC). This study addresses the question of whether genetic convergence occurs among plants with similar adaptive features, specifically focusing on isobilateral leaves in mangrove species. Here, we analyse the genetic convergence of isobilateral leaves in mangroves that have independently adapted to coastal intertidal zones. Our findings reveal that genetic convergence is evident in gene families involved in leaf abaxial and adaxial development, with strong selection pressures identified in photosynthesis and leaf polarity pathways. Despite these adaptations, mangrove species with isobilateral leaves occupy narrower ecological niches and face diminishing suitable habitat areas projected under various HIREC scenarios. These results indicate that while convergent traits enhance local adaptation, they may also increase vulnerability to ongoing environmental changes. This research provides valuable insight into the interplay between genetic adaptation and environmental resilience, underscoring the necessity for targeted biodiversity conservation strategies that safeguard specific adaptive traits amid rapid environmental shifts.

Epigenetic mechanisms, including DNA methylation, histone modifications, and Noncoding RNAs, play a critical role in enabling plants to adapt to environmental changes without altering their DNA sequence. These processes dynamically regulate gene expression in response to diverse stressors, making them essential for plant resilience under changing global conditions. This review synthesises research on tropical and subtropical plants-species naturally exposed to extreme temperatures, salinity, drought, and other stressors-while drawing parallels with similar mechanisms observed in arid and temperate ecosystems. By integrating molecular biology with plant ecology, this synthesis highlights how tropical plants provide valuable models for understanding resilience strategies applicable across broader plant taxa. This review underscores the potential of epigenetic mechanisms to inform conservation strategies and agricultural innovations aimed at bolstering plant resilience in the face of climate change.

Chrysanthemum white rust (CWR), caused by Puccinia horiana Heen., is a serious disease of chrysanthemum worldwide. This disease reduces the quality and yield of Chrysanthemum morifolium, leading to significant losses for chrysanthemum growers and industries. It is often referred to as the 'cancer' of chrysanthemum. The most effective approach to managing CWR is to utilise host resistance. Reactive oxygen species (ROS) are conserved basic defence compounds in higher plants that are generated in response to biotic stresses. This study reported the TGACG-binding (TGA) transcription factor 1 (CmTGA1) in chrysanthemum. Subcellular localisation analysis revealed that CmTGA1 is localised in the nucleus and cytoplasm. Overexpression or knockout of CmTGA1 in chrysanthemum increased or reduced CWR resistance by regulating ROS generation, the activities of antioxidant enzymes, and CmRbohD (a gene mediating ROS generation) expression. Yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays showed that CmTGA1 bound directly to the as-1 element in the promoter region of CmRbohD. Subcellular localisation analysis revealed that CmRbohD was localised in the cytomembrane and cytoplasm. CmRbohD was induced by P. horiana infection and enhanced CWR resistance by promoting ROS generation, activating the antioxidant enzyme system, and catalysing lignin biosynthesis. Our results showed that CmTGA1 activated CmRbohD to improve the CWR resistance via the ROS pathway in chrysanthemum. Our findings provided novel insights into the regulatory pathways involving the CmTGA1-CmRbohD cascade-mediated regulation of CWR resistance, demonstrating an effective strategy to improve tolerance to P. horiana in chrysanthemum.

Drought impacts trees in varied temporal and spatial patterns, suggesting that heterogeneity of below-ground water stores influences the fate of trees under water stress. Karst ecosystems rely on shallow soil overlying bedrock that can store available water in primary pores. A contribution of rock moisture to tree water status has been previously demonstrated, but actual mechanisms and rates of rock-to-root water delivery remain unknown. We report accurate measurements of hydraulic properties of two rock types (Breccia and Dolostone), of typical Karst red soil, and of roots of a common Karst tree species grown under different rock-soil combinations. Experimental data were used to build a water exchange model that supported the hypothesis that roots can extract water from porous and highly conductive rocks (Breccia), but not from more compact ones (Dolostone), especially when plants grow in rocky substrate or experience water stress, and thus have low root hydraulic conductivity and low rates of water extraction from rocks. Our data support the hypothesis that rocks represent important water stores for plants growing in rock-dominated habitats. Heterogeneous rock properties translate into different rates of water delivery to root systems, underlying complex patterns of tree mortality under severe drought stress.

Despite a high sucrose accumulation in its taproot vacuoles, sugar beet (Beta vulgaris subsp. vulgaris) is sensitive to freezing. Earlier, a taproot-specific accumulation of raffinose was shown to have beneficial effects on the freezing tolerance of the plant. However, synthesis of raffinose and other oligosaccharides of the raffinose family depends on the availability of myo-inositol. Since inositol and inositol-metabolising enzymes reside in different organelles, functional inositol metabolism and raffinose synthesis depend on inositol transporters. We identified five homologues of putative inositol transporters in the sugar beet genome, two of which, BvINT1;1 and BvINT1;2, are localised at the tonoplast. Among these, only the transcript of BvINT1;1 is highly upregulated in sugar beet taproots under cold. BvINT1;1 exhibits a high transport specificity for inositol and sugar beet mutants lacking functional BvINT1;1 contain increased inositol levels, likely accumulating in the vacuole, and decreased raffinose contents under cold treatment. Due to the quenching capacity of raffinose for Reactive Oxygen Species (ROS), which accumulate under cold stress, bvint1;1 sugar beet plants show increased expression of both, ROS marker genes and detoxifying enzymes. Based on these findings, we conclude that the vacuolar inositol transporter BvINT1;1 is contributing to ROS-homoeostasis in the cold metabolism of sugar beet.

Temperate fruit trees rely on environmental and endogenous signals to trigger dormancy release and flowering. However, the knowledge of DELLA protein PmRGL2, a Prunus mume homolog of REPRESSOR OF GA-Like 2 (RGL2), which serves as an important inhibitory factor in gibberellin (gibberellin acid [GA]) signalling, is limited related to on its regulatory effects on dormancy release and flowering. In our study, the protein-protein interaction assays showed an interaction between PmRGL2 and PmFRL3, a Prunus mume homolog of FRIGIDA-LIKE (FRL). The FRL protein regulates flowering induction by binding to chaperone proteins. To understand the transcriptional regulation of PmRGL2 in Prunus mume, in detail's we constructed a ChIP-Seq library at four key stages of flower bud development. Genome-wide analysis screened a MCM1-AGAMOUSDEFICIENS Serum Response Factor box (MADS box) protein for two SHORT VEGETATIVE PHASEs (SVPs). Genetic analysis showed that overexpressing PmSVP in Arabidopsis thaliana reduced the GA content and delayed flowering, whereas PmSVP-like overexpression increased the GA content and promoted flowering. Protein-DNA binding assays revealed that the PmRGL2/PmFRL3 protein complex promoted PmSVP transcription while repressing PmSVP-like transcription, which inhibited the flowering process. As chilling requirements increased, the PmFRL3 protein was degraded. ThePmRGL2/PmFRL3 protein complex is disrupted. With the increase in the GA content within the flower buds, the PmRGL2 protein was degraded in response to GA signalling, and the function of PmSVP-like was released. It dominated flowering, leading to this process in Prunus mume. Therefore, we propose a mechanism by which the PmRGL2/PmFRL3 protein complex responds to GA and low-temperature signalling to regulate PmSVP and PmSVP-like synergistically and thus Prunus mume flowering time.

Elucidating the mechanisms underlying heat tolerance in rice (Oryza Sativa. L) is vital for adapting this crop to rising global temperature while increasing yields. Here, we identified a rice mutant, high temperature tolerance 1 (htt1), with high survival rates under heat stress. HTT1 encodes a chloroplast-localized stearoyl-acyl carrier protein (ACP) desaturase involved in the biosynthesis of unsaturated fatty acids, converting C18:0 to C18:1 fatty acid. Overexpression and knockout rice lines provided evidence that HTT1 negatively regulates the response to heat stress. In the htt1 mutant, a G-to-A base substitution in HTT1 impairs unsaturated fatty acid biosynthesis, remodelling the lipid content of cellular membranes and in particular increasing diglyceride contents, which improves membrane stability under heat stress. HTT1 was differentially expressed in all tissues analyzed and was inhibited by heat. Yeast one-hybrid and dual-luciferase reporter assays showed that OsHsfA2d binds to the promoter of HTT1, inhibiting its expression. Different HTT1 alleles were identified between the two Asian cultivated rice subspecies, indica and japonica, potentially facilitating their adaptation to different environmental temperature. Taken together, these findings demonstrate that HTT1 is a previously unidentified negative regulator of heat tolerance and a potential target gene for the improvement of heat adaptability in rice.

Functional redundancy is considered a pivotal mechanism for maintaining the adaptability of species by preventing the loss of key functions in response to dehydration. However, we still lack a comprehensive understanding of the redundancy of leaf hydraulic systems along aridity gradients. Here, photosynthesis (A_n), stomatal conductance (g_s) and leaf hydraulic conductance (K_leaf) during dehydration were measured in 20 woody species from a range of aridity index (AI) conditions and growing in a common garden to quantify stomatal redundancy (SR), the extent of stomatal opening beyond the optimum required for maximum photosynthesis (A_max), leaf hydraulic redundancy (HR), and the extent of leaf hydraulic conductance (K_leaf) beyond the optimum required for maximum g_s (g_s-max). The findings revealed that species from arid habitats tended to have higher SRs but lower HRs than did species from humid habitats. The relatively high SR in arid species arose from relatively high g_s-max values. The relatively low HR arose from the relatively high K_leaf value at a 5% reduction in g_s-max (K_leaf-gs). Our results suggest that greater stomatal redundancy and lower hydraulic redundancy prevent the loss of photosynthesis and water transportation, respectively, and thus might be the key adaptive mechanisms for plants to adapt to drought conditions.

Drought stress reduces leaf net assimilation (A_N) and phloem export, but the equilibrium between the two is unknown. Consequently, the leaf carbon balance and the primary use of the leaf nonstructural carbohydrates (NSC) under water deficit are unclear. Also, we do not know how quickly leaves can replenish their NSC storage and resume export after rehydration. Hence, we dried grapevines to either zero A_N, leaf turgor loss, or complete wilting while following the leaf carbon dynamics. The vines ceased growth and minimized carbon export under drought, conserving the leaves NSC until A_N zeroed. Subsequently, the leaves slowly depleted their NSC storage. However, the NSC depletion rate in the leaves was too slow to support the leaf's energetic requirements, potentially transforming the leaves into carbon sinks. Even under extreme drought (-2 MPa), the leaves had substantial NSC reserves (38% of the controls). After rehydration, all surviving leaves recovered their NSC storage within a week, and even leaves that were later shed had functional phloem export in the week after rehydration. The study reveals the leaf carbon relations under drought, highlighting the preference of the leaf to conserve its NSC storage rather than utilize it.