Plant Physiology and Biochemistry最新文献

In some peanut (Arachis hypogaea L.) producing regions, growth and photosynthesis-limiting low and high temperature extremes are common. Heat acclimation potential of photosynthesis and respiration is a coping mechanism that is species-dependent and should be further explored for peanut. The objectives of the current study are (1) to evaluate the response of photosynthesis, its component processes, and respiration to low and high temperatures, and (2) to determine the heat acclimation potential of photosynthesis and respiration during early vegetative growth of peanut. Peanut was exposed to four different growth temperature regimes: (1) optimum temperature (30/20 °C day/night), (2) low temperature (20/15 °C), (3) moderately high temperature (35/25 °C), and (4) a high temperature extreme (40/30 °C). Low temperature and both high temperatures caused substantial reductions in growth and net photosynthetic rate. Mesophyll conductance and RuBP regeneration co-limited net photosynthetic rate under low temperature. Rubisco carboxylation was the most negatively impacted biochemical processes by high temperatures; however, diffusional limitations were not evident under high temperature conditions. Photosynthesis did not acclimate to high temperatures, while respiration and photorespiration exhibited heat acclimation. The inability of photosynthesis to acclimate to high temperature is likely a major constraint to early season growth in peanut.

The pigments present in the fibers of naturally colored cotton provide excellent antibacterial and environmentally friendly properties, making these colored fibers increasingly favored by the textile industry and consumers. Proanthocyanidins (PAs), the critical pigments responsible for the color of brown cotton fiber, are produced on the endoplasmic reticulum and subsequently transported to the vacuole for polymerization and/or storage. Previous studies have identified GhTT12 as a potential transmembrane transporter of PAs in Gossypium hirsutum, with GhTT12 being a homolog of Arabidopsis Transparent Testa 12 (TT12). Here, we analyzed the spatiotemporal expression pattern of GhTT12, silenced and transiently overexpressed GhTT12 in cotton to confirm its biological function. The GhTT12 protein contains two Multidrug and toxic compound extrusion (MATE) domains and 12 transmembrane helices, and the GhTT12 gene displayed predominant expressions in flowers and fibers of cotton that had higher contents of PAs, particularly in brown cotton, suggesting that GhTT12 may play a role in the transport of PAs in cotton. Silencing or transient overexpression of GhTT12 in cotton resulted in decreased or increased accumulation levels of PAs and anthocyanins (Ans), respectively, accompanied by correspondingly down- or up-regulation of genes involved in PAs synthesis (GhANR) and oxidative polymerization (GhTT10). These findings indicate that GhTT12 may also participate in the biosynthesis of PAs and Ans. Moreover, the silencing of GhTT12 led to a lightening of the color of brown cotton fibers, probably due to the reductions in both PAs content and PAs oxidation. Overall, this study, along with previous research, provides compelling evidence to support the hypothesis that GhTT12 transports PAs and Ans while also regulating their biosynthesis and oxidative polymerization, thereby promoting the accumulation of PAs and Ans in cotton and ultimately affecting the fiber coloration.

To investigate the effect of combined action of discharge plasma (DP) and plasma-activated water (PAW) in mutagenesis breeding, this study focuses on Agropyron mongolicum. We utilized high-voltage DC pulsed dielectric barrier discharge for seed treatment, alone and in combination with PAW. The research focused on germination rates, evolution of physicochemical properties of imbibition residual solution, reactive oxygen species (ROS), malondialdehyde (MDA), and volatile organic compounds (VOCs) to assess DP-induced damage and variability in Agropyron mongolicum. Results indicated that after 18 h of combined treatment, the germination rate of Agropyron mongolicum dropped to 29.67%, below the LD50 threshold. Treated seedlings exhibited elevated ROS and MDA levels compared to controls. The concentration of reactive nitrogen and oxygen species (RONS) in the imbibition residual solution of the combined treatment group was lower than in freshly prepared PAW, indicating RONS penetration into the seed embryo via water, leading to oxidative damage. Enhanced lateral root differentiation, early tillering, increased biomass, and albino variant plants were observed in the surviving seedlings post-treatment. Transmission electron microscope (TEM) and Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) analysis confirmed that plasma treatment induced oxidative damage in Agropyron mongolicum. In conclusion, high-power, long-duration direct DP treatment caused oxidative damage and reduced germination rates in Agropyron mongolicum, with PAW intensifying these effects. PAW was identified as the main driver of variation and lethality, while DP played a supportive role. Combined DP and PAW treatment induced variations in Agropyron mongolicum, providing experimental evidence and theoretical insights for applying DP treatment in plant mutagenesis breeding.

Melatonin (MT) serves as a potent antioxidant in plant organisms, bolstering their resilience to temperature stress. In this study, the impact of MT on various buckwheat varieties under high-temperature stress conditions (40 °C) was investigated. Specifically, five buckwheat seedling varieties, comprising three sweet buckwheat variants (Fagopyrum esculentum) and two bitter buckwheat types (Fagopyrum tataricum), were subjected to foliar sprays of melatonin at concentrations of 50, 100 and 200 μM, with water at 25 °C employed as a control. Results demonstrated that exogenous MT at different concentrations improved the growth and physiological parameters of buckwheats, ameliorating damage induced by high-temperature stress. Notably, the application of 100 μM MT significantly augmented shoot biomasses of buckwheat seedlings under high-temperature conditions. Furthermore, the MT significantly increased the levels of osmotic adjustment substances and chlorophyll concentrations, enhanced antioxidant enzyme activities, chlorophyll fluorescence parameters, and improved photosynthetic gas exchange parameters in five different varieties of buckwheat. This led to the alleviation of damage to buckwheat seedlings subjected to high-temperature stress. Subsequently, five advanced statistical analysis methods: Principal Component Analysis, Grey Relational Analysis, Path Coefficient Analysis, Membership Function Method, and Coupling Coordination Analysis were employed to delve deeper into the existing data indicators. To summarize, the beneficial effect of exogenous melatonin on seedling growth is primarily achieved through the coordination and regulation of the antioxidant enzyme system and osmotic regulatory substances, ensuring the growth and development of buckwheat seedlings while also improving their heat tolerance. The treatment with a concentration of 100 μM of MT was the most effective.

Alkaline salts have more severe adverse effects on plant growth and development than neutral salts do. However, the adaptive mechanisms of plants to alkaline salt stress remain poorly understood, especially at the molecular level. The Songnen Plain in northeast China is composed of typical 'soda' saline-alkali soil, with NaHCO₃ and Na₂CO₃ as the predominant alkaline salts (pH ≥ 9.2). Leymus chinensis can grow on this saline-alkali land, showing strong adaptability. We investigated the role of succinic acid and genes regulating its synthesis in the response to alkaline salt stress in L. chinensis roots. Compared to the neutral salt (NaCl) and high pH treatments, the alkaline salt (NaHCO₃ and Na₂CO₃) treatment specifically caused changes in 11 organic acids, of which the increase in succinic acid was the greatest. The exogenous addition of succinic acid alleviates the damage of alkaline salt to L. chinensis roots. Further, two genes encoding succinyl-coenzyme A ligase (SUCLA) subunits that regulate succinic acid synthesis, LcSUCLAα and LcSUCLAβ, were identified; these genes interact and were localized within mitochondria. Overexpression of LcSUCLAα and LcSUCLAβ caused an increase in succinic acid and enhanced tolerance of NaHCO₃ in transgenic rice seedlings. These results suggest that LcSUCLAα and LcSUCLAβ may be involved in the response to alkaline salt stress through the regulation of succinic acid synthesis.

In this research, we sought to investigate how high temperature, salinity, and CO₂ affect endogenous phytohormones, photosynthesis, and redox homeostasis in Caragana korshinskii Kom (C. korshinskii) leaves, as well as to comprehensively evaluate the plant's physiological response to multiple environmental stressors. The elevated temperature (e[T]), elevated Na⁺ (e[Na]), and elevated temperature and Na⁺ (e[T-Na]) treatments increased abscisic acid (ABA) and reduced zeatin-riboside (ZR), indole-3-acetic acid (IAA), and gibberellic acid (GA₃). These changes induced stomatal closure, and the subsequent reduction in photosynthetic rate triggered the generation of superoxide anion (O₂^·-) and hydrogen peroxide (H₂O₂). In response, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity increased, and free proline and total soluble sugars were accumulated. However, membrane lipid peroxidation was still aggravated. Under elevated CO₂ (e[CO₂]), the dramatic hormonal fluctuations and photosynthetic inhibition resulting from e[T], e[Na], and e[T-Na] were alleviated. Moreover, e[CO₂] reduced ROS generation caused by e[T], e[Na], and e[T-Na], and stabilized antioxidant enzyme activities and non-enzymatic compound concentrations. Compared with e[T], e[Na], and e[T-Na], the increased malondialdehyde (MDA) content was effectively alleviated under elevated CO₂ and temperature (e[CO₂-T]), elevated CO₂ and Na⁺ (e[CO₂-Na]), and elevated CO₂, temperature, and Na⁺ (e[CO₂-T-Na]). Overall, our research suggest that e[CO₂] may alleviate the negative impacts of e[T] and e[Na] on plant physiology.

Selenium nanoparticles are well known for their antioxidant and stress-mitigating properties. In our study, composite nanoformulations of selenium and chitosan have been synthesized. The synthesized composite nanoformulations were 50 nm in diameter, spherical in shape, and had higher antioxidant activities and stability than the selenium and chitosan nanoparticles. In our study, Luit rice seedlings grown in an arsenic-treated Hoagland solution showed a reduction of growth, decreased superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, ascorbate, and glutathione content. Otherwise, superoxide anion, hydrogen peroxide, and malondialdehyde content increased in arsenic-stressed conditions. The alone application of Selenium nanoparticles, chitosan nanoparticles, and their nanoformulation improved growth, reduced stress parameters, and enhanced enzymatic and non-enzymatic activity. Additionally, the reduction of superoxide anion, hydrogen peroxide, and malondialdehyde content was higher by applying composite nanoformulations in arsenic-stressed conditions than selenium and chitosan nanoparticles. The treatment of composite nanoformulation also regulated the enzymatic and non-enzymatic antioxidant activity higher than that of other nanoparticles. It might be due to the higher stability and antioxidant activity of composite nanoformulations than that of selenium and chitosan nanoparticles. Our study suggests that the composite nanoformulation enhanced the growth of rice plants by mitigating arsenic-induced reactive oxygen species and upregulating antioxidant activity.

Flavonol glycosides are secondary metabolites important for plant development and stress defense such as UV-B irradiation. UDP-glycosyltransferase (UGT) catalyzes the last step in the biosynthesis of flavonol glycosides. Eriobotrya japonica is abundant in flavonol glycosides, but UGTs responsible for accumulation of flavonol glycosides remain unknown. Here, 13 flavonol glycosides including monoglycosides and diglycosides were characterized in different tissues of loquat by LC-MS/MS. UV-B irradiation significantly increased the accumulation of four quercetin glycosides and two kaempferol glycosides in loquat fruit. Based on UGT gene family analysis, transcriptome analysis, enzyme assays of recombinant proteins as well as transient overexpression assays in Nicotiana benthamiana, three UGTs were identified, i.e. EjUGT78T4 as flavonol 3-O-galactosyltransferase, EjUGT78S3 as flavonol 3-O-glucosyltransferase, and EjUGT91AK7 as flavonol 1 → 6 rhamnosyltransferase. This work elucidates the formation of flavonol glycosides in loquat through UGT-mediated glycosylation.

Alfalfa (Medicago sativa L.) is a prominent and distinct species within the pasture germplasm innovation industry. However, drought poses a substantial constraint on the yield and distribution of alfalfa by adversely affecting its growth. Although lineage-specific genes are instrumental in modulating plant responses to stress, their role in mediating alfalfa's tolerance to drought stress has yet to be elucidated. In this study, a total of 199 alfalfa-specific genes (ASGs) and 3054 legume-specific genes (LSGs) were identified in alfalfa. Compared with evolutionarily conserved genes, ASGs have shorter sequence length and fewer or no intron. Many alfalfa ASGs can be induced by various abiotic stresses, and the capability of MsASG166 to enhance drought resistance has been substantiated through transgenic research in both yeast and Arabidopsis thaliana. The RNA-Seq and WGCNA analyses revealed that DREB2A and MADS are pivotal genes in the molecular mechanisms through which MsASG166 positively modulates plant drought resistance. This study marks the first identification of lineage-specific genes in alfalfa and an examination of the molecular roles of the MsASG166 gene in drought stress responses. The findings offer valuable genetic resources for the development of novel, genetically engineered alfalfa germplasm with enhanced drought tolerance.

A deep understanding of ammonia (NH₃) emissions from cropland can promote efficient crop production. To date, little is known about leaf NH₃ emissions because of the lack of rapid detection methods. We developed a method for detecting leaf NH₃ emissions based on portable NH₃ sensors. The study aimed to (i) determine the performance of the method in detecting leaf NH₃ emissions; (ii) analyze the variation of leaf NH₃ emissions with foliar rank; and (iii) elucidate the relationships between leaf NH₃ emissions and other leaf parameters. Maize (Zea mays L.) was used as the tested plant. The results showed that the NH₃ sensors had good repeatability, accuracy, and selectivity in detecting NH₃. The response time of the method ranged 7-22 s and the NH₃ reading ranged 0.078-0.463 μmol mol^-1. Leaf NH₃ emissions were observed mainly in daytime (negligible at night). Daytime leaf NH₃ emission rates ranged 0.347-1.725 μg N cm^-2 d^-1. The middle leaves (near the ear) were the major contributor to plant NH₃-N loss. There were significant linear relationships between leaf NH₃ emission rates and other nondestructively-measured leaf parameters [e.g., SPAD (soil and plant analyzer development, which reflects the relative concentration of leaf chlorophyll), stomatal conductance, transpiration rate, and net photosynthetic rate] (p < 0.01), as well as with leaf apoplastic ammonium (NH₄⁺) concentration and leaf total N concentration (p < 0.01). Nitrogen application increased leaf apoplastic NH₄⁺ concentration, leaf total N concentration, and leaf NH₃ emission rate. Overall, nondestructively-measured leaf NH₃ emission rates can partly reflect maize growth status and provide information for N management in maize production.