Plant Physiology and Biochemistry最新文献

Rising atmospheric carbon dioxide (CO₂) and soil heavy metal pollution affect crop safety and production. Exposure to elevated CO₂ (ECO₂) increases cadmium (Cd) uptake in some crops like wheat and rice, however, it remains unclear how ECO₂ affects Cd uptake by Brassica napus. Here, we investigated the responses of B. napus seedlings exposed to ECO₂ and Cd through analyses of physiology, transcriptome, metabolome, and rhizosphere microbes. Compared with Cd-stress alone (Cd50_ACO₂), ECO₂ boosted the uptake of Cd by B. napus roots by 38.78% under coupled stresses (Cd50_ECO₂). The biomass and leaf chlorophyll a content increased by 38.49% and 79.66% respectively in Cd50_ECO₂ relative to Cd50_ACO₂. Activities of superoxide dismutase (SOD) and peroxidase (POD) enhanced by 8.42% and 185.01%, respectively, while glutathione (GSH) and ascorbic acid (AsA) contents increased by 16.44% and 52.48%, and abundances of rhizosphere microbes changed significantly under coupled stresses (Cd50_ECO₂) relative to Cd-stress alone (Cd50_ACO₂). Also, the upregulation of glutathione, glutathione transferase genes, and heavy metal ATPase expression promoted the detoxification effect of rapeseed on Cd. Changes in the expression of transcription factors like MAPK, WRKY, BAK1 and PR1, as well as changes in metabolic pathways like β-alanine, may be involved in the regulatory mechanism of stress response. These findings provide new insights for studying the regulatory mechanism of rapeseed under ECO₂ on soil Cd stress, and also provide a basis for further research on Cd tolerant rapeseed varieties in the future climate context.

In many regions, nitrogen (N) deficiency limits pepper cultivation, presenting significant cultivation challenges. This study investigates the impact of N deficiency and silicon (Si) supplementation on physiological responses and antioxidant modulation in pepper plants, focusing particularly on the homeostasis of carbon (C), nitrogen, and phosphorus (P), and their effects on growth and biomass production. Conducted in a factorial design, the experiment examined pepper plants under conditions of N sufficiency and deficiency, with and without Si supplementation (0.0 mM and 2.0 mM). Results showed that N deficiency sensitizes pepper plants, leading to increased electrolyte leakage (39.59%) and disrupted C, N, and P homeostasis. This disruption manifests as reductions in photosynthetic pigments (−64.53%), photochemical efficiency (−14.92%), and the synthesis of key metabolites such as total free amino acids (−86.97%), sucrose (−53.88%), and soluble sugars (−39.96%), ultimately impairing plant growth. However, Si supplementation was found to alleviate these stresses. It modulated the antioxidant system, enhanced the synthesis of ascorbic acid (+30.23), phenolic compounds (+33.19%), and flavonoids (+7.52%), and reduced cellular electrolyte leakage (−25.02%). Moreover, Si helped establish a new homeostasis of C, N, and P, optimizing photosynthetic and nutritional efficiency by improving the utilization of C (+17.46%) and N (+13.20%). These Si-induced modifications in plant physiology led to increased synthesis of amino acids (+362.20%), soluble sugars (+51.34%), and sucrose (77.42%), thereby supporting enhanced growth of pepper plants. These findings elucidate the multifaceted biological roles of Si in mitigating N deficiency effects, offering valuable insights for more sustainable horticultural practices.

The phenylpropanoid pathway is vital for plant growth and development, producing lignin and flavonoids. This study investigates PtrMYB203, a homolog of MYB repressors of proanthocyanidin (PA) biosynthesis in Populus trichocarpa, as a transcriptional repressor in the phenylpropanoid pathway of hybrid poplar (Populus alba x P. glandulosa). Overexpression of PtrMYB203 (35S::PtrMYB203) in hybrid poplar detrimentally impacted plant growth and development. Histological analysis revealed irregular xylem vessel formation and decreased lignin content, corroborated by Klason lignin assays. Moreover, 35S::PtrMYB203 transgenic poplars exhibited significant decreases in anthocyanin and PA accumulations in callus tissues, even under high light conditions. Quantitative RT-PCR analysis and protoplast-based transcriptional activation assay confirmed the downregulation of lignin and flavonoid biosynthesis genes. This genetic modification also alters the expression of several MYB transcription factors, essential for phenylpropanoid pathway regulation. Remarkably, saccharification efficiency in the 35S::PtrMYB203 poplar was improved by over 34% following hot water treatment alone. These findings suggest PtrMYB203 as a potential genetic target for enhancing wood properties for bioenergy production, providing valuable insights into the manipulation of metabolite pathways in woody perennials to advance wood biotechnology.

The trihelix transcription factor (GT) gene family members play vital roles in plant growth and development, responses to abiotic or biotic stress, and fruit ripening. However, its role in banana fruit ripening remains unclear. Here, 59 MaGT gene members were identified in banana and clustered into five subfamilies, namely GT1, GT2, GTγ, SIP1, and SH4. This classification is completely supported by their gene structures and conserved motif analysis. Transcriptome data analysis indicated that MaGT14, MaGT21, and MaGT27 demonstrated significant differential expression during fruit ripening. Quantitative real-time PCR analysis revealed that these three genes were highly induced by ethylene treatment, responded to cold and heat stress, and had a high expression abundance in ripe fruit. Subcellular localization demonstrated that MaGT21 and MaGT27 functioned as nuclear proteins, while MaGT14 functioned as a nuclear and cell membrane protein. Further investigation indicated MaGT21 could positively stimulate the transcription of the key ethylene biosynthesis gene MaACO1 by directly targeting the GT motif in the promoter. MaGT21 transient overexpression in banana fruit upregulated MaACO1 and accelerated fruit ripening. Our findings provide comprehensive and valuable information for further functional studies of MaGT genes in banana, help to understand the roles of MaGTs during banana fruit ripening.

Living organisms have developed finely regulated homeostatic networks to mitigate the effects of environmental fluctuations in transition metal micronutrients, including iron, zinc, and copper. In Saccharomyces cerevisiae, the tandem zinc-finger protein Cth2 post-transcriptionally regulates gene expression under conditions of iron deficiency by controlling the levels of mRNAs that code for non-essential ferroproteins. The molecular mechanism involves Cth2 binding to AU-rich elements present in the 3′ untranslated region of target mRNAs, negatively affecting their stability and translation. Arabidopsis thaliana has two TZF proteins homologous to yeast Cth2, C3H14 and C3H15, which participate in cell wall remodelling. The present work examines the expression of representative metal homeostasis genes with putative AREs in plants with altered levels of C3H14 and C3H15 grown under varying metal availabilities. The results suggest that C3H15 may act as a post-transcriptional plant modulator of metal adequacy, as evidenced by the expression of SPL7, the main transcriptional regulator under copper deficiency, and PETE2, which encodes plastocyanin. In contrast to S. cerevisiae, the plant C3H15 affects copper and zinc homeostasis rather than iron. When grown under copper-deficient conditions, adult C3H15^OE plants exhibit lower chlorophyll content and photosynthetic efficiency compared to control plants, suggesting accelerated senescence. Likewise, metal content in C3H15^OE plants under copper deficiency shows altered mobilization of copper and zinc to seeds. These data suggest that the C3H15 protein plays a role in modulating both cell wall remodelling and metal homeostasis. The interaction between these processes may be the cause of altered metal translocation.

With global climate change, the frequent occurrence of intense rainfall and aggravation of waterlogging disasters have severely threatened the plant growth and fruit quality of grapevines, which are commercially important fruit crops worldwide. There is accordingly an imperative to clarify the responses of grapevine to waterlogging and to propose appropriate remedial measures. Strigolactone (SL) is a phytohormone associated with plant abiotic stress tolerance, while, its function in plant responses to waterlogging stress remain undetermined. In this study, systematic analyses of the morphology, physiology, and transcriptome changes in grapevine leaves and roots under post-waterlogging and GR24 (a synthetic analog of SL) treatments were performed. Morphological and physiological changes in grapevines in response to post-waterlogging stress, including leaf wilting and yellowing, leaf senescence, photosynthesis inhibition, and increased anti-oxidative systems, could be alleviated by the application of GR24. Moreover, transcriptome analysis revealed that the primary gene functions induced by post-waterlogging stress changed over time; however, they were consistently associated with carbohydrate metabolism. The GR24-induced leaf genes were closely associated with carbohydrate metabolism, photosynthesis, antioxidant systems, and hormone signal transduction, which were considered vital aspects that were influenced by GR24 in grapevine to induce post-waterlogging tolerance. Concerning the roots, an enhancement of microtubules and cytoskeleton for cell construction in GR24 application was proposed to facilitate root system recovery after waterlogging. With this study, we comprehend the knowledge regarding the responses of grapevines to post-waterlogging and the ameliorative effect of GR24 with the insight to the transcriptome changes during these processes.

Soil salinization is a major environmental factor that severely affects global agriculture. Root endophytes can enter root cells, and offer various ecological benefits, such as promoting plant growth, improving soil conditions, and enhancing plant resistance. Su100 is a novel strain of endophytic fungus that was characterized from blueberry roots. In this study, we focused on evaluating the effects of Su100 secretion on maize growth. The results demonstrated that maize treated with Su100 fermentation broth (SFB) exhibited significantly stronger salt tolerance than the control. It is worth mentioning that the treated root system not only had an advantage in terms of biomass but also a change in root structure with a significant increase in lateral roots (LRs) compared to the control. Transcriptome analysis combined with hormone content measurements indicated that SFB upregulated the auxin signaling pathway, and also caused alterations in brassinosteroids (BR) and jasmonic acid (JA) biosynthesis and signaling pathways. Transcriptome analyses also indicated that SFB caused significant changes in the sugar metabolism of maize roots. The major changes included: enhancing the conversion and utilization of sucrose in roots; increasing carbon flow to uridine diphosphate glucose (UDPG), which acted as a precursor for producing more cell wall polysaccharides, mainly pectin and lignin; accelerating the tricarboxylic acid cycle, which were further supported by sugar content determinations. Taken together, our results indicated that the enhanced salt tolerance of maize treated with SFB was due to the modulation of sugar metabolism and phytohormone biosynthesis or signaling pathways. This study provided new insights into the mechanisms of action of endophytic fungi and highlighted the potential application of fungal preparations in agriculture.

Photosynthesis in fluctuating light requires coordinated adjustments of diffusion conductance and biochemical capacity, but the role of chloroplast ATP synthase activity (g_H⁺) in dynamic photosynthesis is not well understood. In this study, we measured gas exchange, chlorophyll fluorescence and electrochromic shift signals in fluctuating light for leaves of tomato (Solanum lycopersicum) and maize (Zea mays). During the transition from sun to shade, simultaneous increases in g_H⁺, effective quantum yield of PSII, and net CO₂ assimilation rate (A_N) occurred in tomato but uncoupled in maize, indicating that g_H ⁺ limited A_N during the sun-to-shade transition in tomato but not in maize. During the shade-to-sun transition, g_H ⁺ increased simultaneously with stomatal conductance, mesophyll conductance and Rubisco carboxylation capacity in tomato, suggesting that g_H⁺ is an overlooked factor affecting light induction of A_N in tomato. By comparison, g_H ⁺ maintained at high levels in maize and its A_N was mainly restricted by stomatal conductance. Our results reveal that the kinetics of g_H⁺ in fluctuating light differs between species, and chloroplast ATP synthase may be a potential target for improving dynamic photosynthesis in crops such as tomato.

In recent years, the widespread application of growth regulators and nutrients to boost yield and quality of strawberry fruits has led to the rapid growth of strawberry industry globally. Although the effects of major nutrients on strawberry yield have been widely studied, investigations into the effect of trace elements such as boron remain limited. This study examined the effect of boron application on the yield and quality of “Benihoppe” strawberry fruits. Nutrient solutions with varying boron concentrations (0, 0.024, 0.048, 0.072, and 0.096 mM) were applied to the plants, and their effect on fruit quality was evaluated. The results indicated that boron application enhanced the yield per plant, nutrient composition (total amino acid and vitamin C content), antioxidant properties (total phenol) and volatile components (esters) in strawberry fruits. Specifically, treatment with 0.048 mM boron concentration significantly increased the accumulation of soluble sugars, such as sucrose, whose concentration was 154.29% higher than that of the control treated with 0 mM concentration. This enhancement is attributable to the regulated expression of sucrose phosphate synthase (maker-Fvb2-2-augustus-gene-229.38) and β-fructofuranosidase-1/2/3 (augustus-masked-Fvb5-4-processed-gene-2.0, maker-Fvb5-3-augustus-gene-272.30, and maker-Fvb5-1-augustus-gene-0.37) genes, which play crucial roles in sugar metabolism and enzyme activity. Overall, boron application enhanced the quality of “Benihoppe” strawberries. The findings of this study offer substantial theoretical and practical guidance for using boron fertilizers in strawberry farming.

The transcription factor Ethylene Responsive Factor (ERF) is crucial for responding to various environmental stressors. Proteins containing the ERF-associated amphiphilic repression (EAR) motif often inhibit gene expression. However, the functions of LkERF, an EAR motif-containing protein from Larix kaempferi, especially in reactive oxygen species (ROS) homeostasis, are not well understood. In the present research, we introduce a novel transcription factor, LkERF6, which contains an EAR motif and positively regulates gene expression, thereby enhancing drought and salt tolerance in tobacco. LkERF6 is classified within the ERF-B1 subfamily due to its conserved AP2/ERF domain and EAR motif. Subcellular localization assays demonstrated LkERF6 is primarily localized in the nucleus. Further analysis revealed that LkERF6 interacts with GCC and DRE elements and is significantly induced by NaCl and PEG₆₀₀₀. Moreover, LkERF6 transgenic tobacco plants exhibit lower ROS accumulation and higher levels of antioxidant enzyme activities. Additionally, correlation analysis identified a strong association between LkERF6 and three genes: LkSOD, LkCCS, and LkCAT. Y1H, EMAS, and DLR assays confirmed that LkERF6 directly interacts with the promoters of these genes through GCC-box and DRE-box to activate their expression. These findings shed new light on the function of EAR motif-containing transcription factors and highlight LkERF6's crucial role in enhancing abiotic stress resistance by activating multiple ROS clearance genes.