Plant Physiology and Biochemistry最新文献

Excess antimony (Sb) has been shown to damage plant growth. Rice plants readily absorb a large amount of Sb after a long period of flooding, yet the mechanisms underlying Sb toxicity in plants have not been solved. This study was conducted to explore the effects of Sb on the uptake of N and S, and monitor the concentrations of reduced glutathione (GSH) and enzymes associated with these processes. In addition, we analyzed differentially expressed metabolites (DEMs) correlated with amino acids (AAs) and oligopeptides, specifically DEMs containing sulfur (S), GSH and indole–3–acetic acid (IAA). The results showed that antimonite [Sb(III)] inhibited shoot growth whereas antimonate [Sb(V)] stimulated shoot growth. Interestingly, Sb(III)_5/10 enhanced shoot concentrations of total nitrogen (N), NH₄⁺–N [only at Sb(III)₁₀] and S; but reduced the shoot concentrations of NO₃–N and soluble protein. Sb(III)_5/10 addition significantly increased oxidized glutathione (GSSG) concentration and activities of glutathione peroxidase (GSH–Px) and glutathione S-transferase (GST) but non–significantly affected concentration of reduced glutathione (GSH) and activities of γ-glutamylcysteine synthetase (GCL) and glutathione reductase (GR), suggesting Sb(III) restricted GSH recycling. Addition of Sb (1) increased the abundance of DEMs associated with lignins, Ca uptake, toxicity/detoxification, and branched chain AAs; (2) decreased the abundance of AAs inclcuding isoleucine (Ile), leucine (Leu), tryptophan (Trp), tyrosine (Tyr) and histidine (His); (3) increased the abundance of arginine (Arg), putrescine (Put) and spermidine (Spd); and (4) affected methylation and acetylation of many AAs, especially acetylation.

Aluminum (Al) stress is a significant issue in acidic soils, severely affecting crop growth and yield. Rice is notably resilient to Al toxicity, yet the internal tolerance mechanisms remain inadequately addressed. Here, we examined the role of OsTIP2;1, a tonoplast-bound intrinsic protein (TIP), in rice's internal Al detoxification. Our findings reveal that OsTIP2;1 expression was quickly and explicitly activated by Al ions in roots but not in shoots. The OsTIP2;1-GFP protein localizes to the tonoplast in plant and yeast cells. Non-functional ostip2;1 rice mutants were more vulnerable to Al toxicity. In the roots, the ostip2;1 mutants exhibited considerably lower levels of Al in the cell sap, primarily the vacuolar contents, than in the wild-type plant. Moreover, the ostip2;1 mutants showed reduced Al accumulation in the roots but increased translocation to the shoots. Heterologous expression of tonoplast-localized OsTIP2;1 in yeast led to enhanced Al tolerance, suggesting that OsTIP2;1 facilitates Al sequestration to the vacuole. These findings indicate that OsTIP2;1 mediates internal detoxification by transporting Al into the vacuole in the root and restricting its transport to above-ground tissues, thus contributing to Al resistance in rice.

Histidine biosynthesis is essential for the growth and development of plants, where it occurs within chloroplasts. The eleven reactions are catalyzed by eight enzymes, known as HISN1-8, each acting sequentially. Here, we present the crystal structures of a 5′-ProFAR isomerase (HISN3) from the model legume Medicago truncatula bound to its enzymatically synthesized substrate (ProFAR) and product (PrFAR). The active site of MtHISN3 contains a sodium cation that participates in ligand recognition, a feature not observed in bacterial and fungal structures of homologous enzymes. The steady-state kinetics of wild-type MtHISN3 revealed a slightly higher turnover rate compared to its bacterial homologs. Plant HISN3 sequences contain an unusually elongated Lys60-Ser91 fragment, while deletion of the 74–80 region resulted in a 30-fold loss in catalytic efficiency compared to the wild-type. Molecular dynamics simulations suggested that the fragment facilitates product release, thereby contributing to a higher k_cat. Moreover, conservation analyses suggested a non-cyanobacterial origin for plant HISN3 enzymes, which is another instance of a non-cyanobacterial enzyme in the plant histidine biosynthetic pathway. Finally, a virtual screening campaign yielded five molecules, with the energy gains ranging between −13.6 and −13.1 kcal/mol, which provide new scaffolds for the future development of herbicides.

Providing food with nutrition and functionality is crucial for sustaining human life. Rice (Oryza sativa L.) is a representative staple crop with high carbohydrate content but low amounts of essential amino acids, micronutrients, and carotenoids such as provitamin A. To improve the nutritional quality, rice endosperm was biofortified to accumulate carotenoids such as β-carotene through genetic engineering (i.e., using synthetic carotenoid biosynthetic genes, a nonmammalian viral polycistronic sequence, and an optimized promoter and transit peptide) and high-throughput rice transformation (approximately 300 transgenic plants per construct). To facilitate the safety assessment of genetically modified food, molecular characterization was performed to select elite lines equipped with a single intergenic insertion of T-DNA, high transgene expression, in this case leading to high carotenoid content, and with phenotypic and compositional substantial equivalence. In this study, we present β-carotene-biofortified rice event candidate lines eligible for commercial use and a disclosed molecular protocol for the development of biotech rice crops.

With progress in technology, soaring demand for lithium (Li) has led to its release into the environment. This study demonstrated the mitigation of the adverse effects of Li stress on tomato (Solanum lycopersicum L.) by the application of waste materials, namely coconut shell biochar (CBC) and steel slag (SS). To explore the impact of Li treatment on tomato plants different morphological, biochemical parameters and plant defense system were analyzed. Tomato plants exposed to Li had shorter roots and shoots, lower biomass and relative water contents, and showed decreases in physiological variables, as well as increases in electrolyte leakage and lipid peroxidation. However, the application of CBC and SS as passivators, either singly or in combination, increased growth variables of tomato and relieved Li-induced oxidative stress responses. The combined CBC and SS amendments reduced Li accumulation 82 and 90% in tomato roots and shoots, respectively, thereby minimizing the negative impacts of Li. Antioxidant enzymes SOD, CAT, APX and GR reflected 4, 5, 30, and 52% and glyoxalase enzymes I and II 7 and 250% enhancement in presence of both CBC and SS in Li treated soil, with a concurrent decrease in methylglyoxal content. Lithium treatment triggered oxidative stress, increased enzymatic and non-enzymatic antioxidant levels, and induced the synthesis of thiols and phytochelatins in roots and shoots. Hence, co-amendment with CBC and SS protected tomato plants from Li-induced oxidative damage by increasing antioxidant defenses and glyoxalase system activity. Both CBC, generated from agricultural waste, and SS, an industrial waste, are environmentally benign, safe, economical, and non-hazardous materials that can be easily applied on a large scale for crop production in Li-polluted soils. The present findings highlight the novel reutilization of waste materials as renewable assets to overcome soil Li problems and emphasize the conversion of waste into wealth and its potential for practical applications.

Transcription factors (TFs) are crucial for regulating fruit ripening in tomato (Solanum lycopersicum). The GRAS (GAI, RGA, and SCR) TFs are involved in various physiological processes, but their role in fruit ripening has seldom been reported. We have previously identified a gene encoding GRAS protein named SlFSR (Fruit Shelf-life Regulator), which is implicated in fruit ripening by regulating cell wall metabolism; however, the underlying mechanism remains unclear. Here, we demonstrate that SlFSR proteins are localized to the nucleus, where they could bind to specific DNA sequences. SlFSR acts downstream of the master ripening regulator RIN and could collaborate with RIN to control the ripening process by regulating expression of ethylene biosynthesis genes. In SlFSR-CR (CRISPR/Cas9) mutants, the initiation of fruit ripening was not affected but the reduced ethylene production and a delayed coloring process occurred. RNA-sequencing (RNA-seq) and promoter analysis reveal that SlFSR directly binds to the promoters of two key ethylene biosynthesis genes (SlACO1 and SlACO3) and activates their expression. However, SlFSR-CR fruits displayed a significant down-regulation of key rate-limiting genes (SlDXS1 and SlGGPPS2) in the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway, which may account for the impaired lycopene synthesis. Altogether, we propose that SlFSR positively regulates ethylene biosynthesis and lycopene accumulation, providing valuable insights into the molecular mechanisms underlying fruit ripening.

‘Benihoppe’ and ‘Fenyu No.1’ are representative varieties of red and pink strawberries in China, possess distinct hue and flavor profiles. This study analyzed the underlying biochemical and molecular differences of two varieties utilizing transcriptomics and high-performance liquid chromatography (HPLC). Ripening ‘Benihoppe’ fruits accumulated more sucrose and pelargonin-3-glucoside (P3G) with a little cyanidin and higher firmness. Whereas ripening ‘Fenyu No.1’ fruits contained more fructose, glucose, malic acid and ascorbic acid (AsA), but less P3G and citric acid. Moreover, genotype significantly influenced phenolic compounds contents in strawberries. Transcriptome analysis revealed that pectin degradation (PL, PG, PE), sucrose synthesis (CWINV, SUS, TPS) and citric acid metabolism (α-OGDH, ICDH, GAD, GS, GDH, PEPCK, AST) were weakened in ‘Benihoppe’ fruit. In contrast, the synthesis of sucrose (CWINH, SPS), citric acid (CS, PEPC), anthocyanin (F3H, F3′H, F3′5′H, DFR, UFGT and ANS), and citric acid transport (V-ATPase) was enhanced. In ‘Fenyu No.1’ fruit, the degradation of sucrose, citric acid, and pectin was enhanced, along with the synthesis of malic acid (ME) and ascorbic acid (PMM, MDHAR and GaLUR). However, anthocyanins synthesis, glucose metabolism (HK, G6PI, PFK, G6PDH, PGK, PGM, ENO, PK), fructose metabolism (FK), citric acid synthesis and transport, and AsA degradation (AO, APX) were relatively weak. RT-qPCR results corroborated the transcriptome data. In conclusion, this study revealed the distinctions and characteristics of strawberries with different fruit colors regarding texture, flavor and color formation processes. These findings offer valuable insights for regulating metabolic pathways and identifying key candidate genes to improve strawberry quality.

High-affinity potassium transporters (HKTs) are well known proteins that govern the partitioning of Na⁺ between roots and shoots. Six HvHKTs were identified in barley and designated as HvHKT1.1, HvHKT1.3, HvHKT1.4, HvHKT1.5, HvHKT2.1 and HvHKT2.2 according to their similarity to previously reported OsHKTs. Among these HvHKTs, HvHKT1.4 was highly up-regulated under salinity stress in both leaves and roots of Golden Promise. Subcellular localization analysis showed that HvHKT1.4 is a plasma-membrane–localized protein. The knockout mutants of HvHKT1.4 showed greater salinity sensitivity and higher Na⁺ concentration in leaves than wild-type plants. Haplotype analysis of HvHKT1.4 in 344 barley accessions showed 15 single nucleotide substitutions in the CDS region, belonging to five haplotypes. Significant differences in mean salinity damage scores, leaf Na⁺ contents and Na⁺/K⁺ were found between Hap5 and other haplotypes with Hap5 showing better salinity tolerance. The results indicated that HvHKT1.4 can be an effective target in improving salinity tolerance through ion homeostasis.

Climate change will bring the interaction of stresses such as increased temperature and drought under high [CO₂] conditions. This is likely to impact on crop growth and productivity. This study aimed to (i) determine the response of barley water relations to vegetative and anthesis drought periods under triple interaction conditions, (ii) test the possibility to prime barley plants for drought, and (iii) analyse the involvement of aquaporins in (i) and (ii). The water status of barley was not affected by drought at the vegetative stage, regardless of the environmental conditions. At the anthesis stage, when the water shortage period was more severe, barley plants growing under combined elevated CO₂ and temperature conditions were able to maintain a better water status compared with plants grown under current conditions. Elevated CO₂ and temperature conditions reduced the stomatal conductance and slowed down the plant water flow through a root-leaf hydraulic conductivity coordination. Leaf HvPIP2;1 and HvTIP1;1 aquaporins seemed to play a key role regulating barley's water flow, while leaf and root HvPIP2;5 provided basic level of water flow. At anthesis drought and under future combined conditions, plants showed a reduced cell dehydration and decrease in leaf relative water content compared with plants grown under current conditions. Exposure to a previous drought did not prime the water status of barley plants to a subsequent drought, but instead worsened the response under future conditions. This was due to an imbalance between the roots versus shoot development.

Industrialization-driven surface ozone (O₃) pollution significantly impairs plant growth. This study evaluates the effectiveness of exogenous protectants [3 mg L⁻¹ abscisic acid (ABA), 400 mg L⁻¹ ethylenediurea (EDU), and 80 mg L⁻¹ spermidine (Spd)] on Trifolium repens subjected to O₃ stress in open-top chambers, focusing on plant growth and dynamics of culturable endophytic fungal communities. Results indicate that O₃ exposure adversely affects photosynthesis, reducing root biomass and altering root structure, which further impacts the ability of plant to absorb essential nutrients such as potassium (K), magnesium (Mg), and zinc (Zn). Conversely, the application of ABA, EDU, and Spd significantly enhanced total biomass and chlorophyll content in T. repens. Specifically, ABA and Spd significantly improved root length, root surface area, and root volume, while EDU effectively reduced leaves' malondialdehyde levels, indicating decreased oxidative stress. Moreover, ABA and Spd treatments significantly increased leaf endophytic fungal diversity, while root fungal abundance declined. The relative abundance of Alternaria in leaves was substantially reduced by these treatments, which correlated with enhanced chlorophyll content and photosynthesis. Concurrently, EDU and Spd treatments increased the abundance of Plectosphaerella, enhance the absorption of K, Ca, and Mg. In roots, ABA treatment increased the abundance of Paecilomyces, while Spd treatment enhanced the presence of Stemphylium, linked to improved nitrogen (N), phosphorus (P), and K uptake. These findings suggest that specific symbiotic fungi mitigate O₃-induced stress by enhancing nutrient absorption, promoting growth. This study highlights the potential of exogenous protectants to enhance plant resilience against O₃ pollution through modulating interactions with endophytic fungal communities.