Plant Physiology and Biochemistry最新文献

Plants encounter various environmental stresses throughout development, including shade, high light, drought, hypoxia, extreme temperatures, and metal toxicity, all of which adversely affect growth and productivity. Organic acids (OAs), besides serving as intermediates in the tricarboxylic acid (TCA) cycle, play crucial roles in multiple metabolic pathways and cellular compartments, including mitochondrial metabolism, amino acid metabolism, the glyoxylate cycle, and the photosynthetic mechanisms of C4 and CAM plants. OAs contribute to stress tolerance by acting as root chelating agents, regulating ATP production, and providing reducing power for detoxifying reactive oxygen species (ROS). They also participate in the biosynthesis of solutes involved in stress signaling and osmoregulation, particularly during stomatal movements. This review explores how OAs regulate plant metabolism in response to specific abiotic stresses, emphasizing the increased production of malate, citrate, and succinate, which enhance resilience to water deficits, metal toxicity, and flooding. Since these mechanisms involve intricate metabolic networks, changes in OA metabolism present promising and underexplored potential for agriculture. Understanding these mechanisms could lead to innovative strategies for developing crops with greater resilience to climate change, whether through genetic manipulation or by selecting varieties with favorable metabolic responses to stress.

Purslane is a plant with high nutritional content that is mainly produced in the central part of Mexico. The nutritional content of purslane depends on various factors such as climatic and soil conditions, phenology, and fertilization. This article describes the ¹H NMR metabolomics profiling of purslane in relation to fertilization at two harvest stages: C₁ and C₂ (27 and 42 days after emergence). During the first stage, 30 metabolites were identified including free amino acids and organic acids. In the second stage, 35 metabolites were identified, with higher concentrations of carbohydrates and nucleosides being observed. Multivariate analysis revealed differences in the metabolome between harvests C₁ and C₂. Notably, higher abundances of fructose, galactose, α-glucose, β-glucose, myo-inositol, sucrose, and nucleosides such as adenosine and uridine were observed in C₂. Discriminant analysis further demonstrated variations in metabolites among plants treated with different doses of nitrogen, phosphorus, and potassium at the two harvest stages studied. Plants treated with the highest dose of nitrogen (300 kg N ha^-1) exhibited maximum levels of metabolites, while low nitrogen-treated plants (0 kg N ha^-1) displayed an inverse trend. Amino acids such as alanine, asparagine, GABA, glutamine, histidine, isoleucine, leucine, phenylalanine, proline, threonine, tyrosine, and valine were found to be the most abundant in plants treated with N₃₀₀. In contrast, untreated plants showed higher levels of citric acid and malic acid. Our results highlight the effectiveness of ¹H NMR as a methodology for understanding the role of fertilization and nutrient content in optimizing the crop production of purslane.

Phoebe zhennan is a high-quality timber tree species mainly distributed in the subtropical regions of China. It is very important to study and improve the cold resistance of P. zhennan from the mechanism and practice for expanding its introduction and cultivation range. However, there is a lack of research on the cold resistance mechanisms of Zhennan seedlings. The present study investigated the effects of exogenous Ca²⁺ on the cold resistance in Zhennan. The results showed that Ca²⁺ pretreatment increased the levels of abscisic acid, peroxidase, catalase, proline, and soluble sugar and decreased the levels of malondialdehyde and relative electrical conductivity. In addition, RNA sequencing was used to investigate the global transcriptome response to cold stress. Gene set enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and gene ontology analysis were used to compare the differentially expressed genes before and after calcium treatment and before and after cold stress. These analyses together with the short time sequence clustering analysis of transcriptome data and predictive protein interaction analysis showed that the transcription factors PzWRKY71, PzTAF, and PzMYB7 play key roles in the regulation of and balance between cold resistance and growth in immune system. Moreover, it was found that the mechanisms of protein phosphorylation and ubiquitin-mediated protein degradation significantly affected the calcium ion-mediated cold resistance mechanism, and there was a complex regulatory relationship between them. The results provide valuable insights into the Ca²⁺-mediated cold resistance mechanism and have potential applications for improving cold stress tolerance in Zhennan seedlings.

The sporogenous yeast Pichia caribbica, a part of the Meyerozyma guilliermondii species complex is found in various environmental niches due to its diverse physiological and metabolic capacities that enhance adaptation and survival. This study examined the application of phytic acid (PA) to improve the biological control efficiency of P. caribbica against natural decay and to preserve the quality of table grape berries. The mechanisms by which PA enhances P. caribbica's biocontrol efficiency were investigated. The yeast cultured in nutrient yeast dextrose broth (NYDB) with (YE) or without (Y) PA was assessed for its ability to produce biofilms and to withstand induced oxidative stress. It was observed that supplementation with 10 μmol/mL PA markedly increased the proliferation and the capacity of P. caribbica to form biofilms (OD₅₉₀ = 0.8) in vitro compared to the non-supplemented yeast (OD₅₉₀ = 0.69). Additionally, P. caribbica cultured with PA (10 μmol/mL) effectively improved tolerance to induced oxidative stress. Phytic acid pretreatment also boosted the activities of defense antioxidant enzymes including β-1,3-glucanase (GLU), catalase (CAT), and superoxide dismutase (SOD) in P. caribbica. The impact of 10 μmol/mL PA on the biocontrol efficacy of P. caribbica led to favourable changes in the physicochemical parameters of table grapes with significantly improved control of the natural decay for fruits stored at ambient and cold conditions. These findings suggest that PA enhances the biocontrol effectiveness of P. caribbica, paving the way for the development of sustainable alternative solutions to combat postharvest fungal phytopathogens. Moreover, consumers preferred table grape bunches treated with YE appreciating the overall cluster appearance, the berry's textural crunchiness, a pronounced berry fragrance, and limited decay. They prioritized fruits stored at 4 °C.

Heat shock transcription factor (HSF) is one of the most important regulatory elements in plant development and stress response. Rhohomyrtus tomentosa has many advantages in adapting to high temperature and high humidity climates, whereas its inherence has barely been elucidated. In this study, we aimed to characterize the HSF family and investigate the thermal adaptation mechanisms of R. tomentosa. We identified 25 HSF genes in the R. tomentosa genome. They could be classified into three classes: HSFA, HSFB, and HSFC. Gene duplication events are major motivations for the expansion of the RtHSF gene family. Most of the genes in the same subclass share similar conserved motifs and gene structures. The cis-acting elements of the promoter regions of RtHSF genes are related to development, phytohormone signaling, and stress responses, and they vary among the genes even in the same subclass, resulting in different expression patterns. Especially, there exists subfunctionalization in the RtHSFA2 subfamily in responding to various abiotic stresses, viz. RtHSFA2a is sensitive to drought, salt, and cold stresses, whilst RtHSFA2b is mainly induced by heat stress. We further proved that RtHSFA2b might be of more importance in R. tomentosa thermotolerance, for Arabidopsis plants with overexpressed RtHSFA2b outperformed those with RtHSFA2a under heat stress, and RtHSFA2b had much higher transcription activity than RtHSFA2a in regulating certain heat shock response (HSR) genes. RtHSFA2a plays a role in transactivating RtHSFA2b. All these results provide a general prospect of the RtHSF gene family and enclose a basal thermal adaptation mechanism of R. tomentosa.

With the intensification of climate change coupled with the inadequate agricultural management in certain regions, plants face numerous challenges due to various abiotic stresses. Stress associated proteins (SAPs) are essential functional genes in plants for coping with stress. This research provides a functional analysis of OsSAP17, a protein belonging to the SAP family in rice. The expression level of OsSAP17 was induced under drought, salt stress and ABA treatment. Subcellular localization analysis revealed that the OsSAP17 protein was distributed in both the cytoplasm and nucleus. The ectopic expression of OsSAP17 significantly increased the capacity to withstand drought and salt stress in both transgenic yeast and Arabidopsis. Additionally, the ectopic expression of OsSAP17 led to notable changes in the expression of Arabidopsis ABA-related genes, including AtNCED3, AtABA2, and AtSnRK2.2. These results indicated that OsSAP17 was able to positively regulate drought and salt tolerance in plants. The insights from this study provided a fundamental understanding of the role of OsSAP17 in abiotic stress response mechanisms and were potentially valuable for breeding crops with enhanced stress tolerance.

Anthocyanin is the primary color-developing component in the pericarp of the passion fruit. Although the pericarp of the passion fruit is anticipated to be a significant source of anthocyanin, however, information regarding anthocyanin biosynthesis in the passion fruit pericarp remains unexplored. Based on metabolomics analysis, a total of five anthocyanins were identified in the purple-skinned passion fruit pericarp, among which three anthocyanins, petunidin-3-O-arabinoside, geranylgeranyl-3,5-O-diglucoside, and petunidin-3-O-rutinoside, play key roles in the coloration of the passion fruit pericarp. Based on proteomics analysis, a total of nine differential proteins are involved in the flavonoid metabolic process, which involves the following chalcone isomerase, flavonol synthase and anthocyanin synthasein. These proteins play important regulatory roles in anthocyanin biosynthesis and are the key regulators in anthocyanin accumulation. qRT-PCR was used to identify nine structural genes (PePAL2, PePAL4, PeC4H1, Pe4CL5, Pe4CL6, Pe4CL7, PeCHS2, PeCHS3 and PeUFGT2) playing key regulatory roles in anthocyanin synthesis in purple passion fruit pericarp. This study is expected to lay a foundation for the subsequent exploration of the regulatory mechanism of anthocyanin biosynthesis and the functional identification of related genes in passion fruit pericarp, and also to provide data support for the in-depth utilization of passion fruit resources.

Manganese (Mn) is an essential element for plant growth but can be toxic at high levels. Pecan (Carya illinoensis), an important nut-producing species, has been observed to exhibit tolerance to high Mn levels. In this study, pecan seedlings were exposed to a nutrient solution containing either 2 μM (control) or 1000 μM (excess) MnSO₄ to investigate the physiological mechanisms. Despite substantial increases in Mn concentration in all pecan tissues, the presence of excess Mn did not induce visible symptoms of Mn toxicity on pecan leaves, nor did it result in any changes in malondialdehyde (MDA) levels. Photosynthetic rate and chlorophyll fluorescence parameters also remained unchanged. Subsequent examination revealed more cell layers and greater cell numbers in leaf palisade mesophyll tissue of Mn-treated plants compared with the control group. Cell length, and cell area decreased significantly in response to excess Mn, but total chloroplast area was unchanged and chloroplast structure remained intact. Subcellular fractionation analysis demonstrated that the cell walls, and to a lesser extent the soluble fraction, contained the majority of the Mn in leaves. The presence of excess Mn caused a marked increase in leaf concentrations of malic acid and citric acid, potential chelators of Mn. Our results suggest that the majority of Mn was sequestered in the leaf cell walls and may have been present as less-toxic chelated organic acids, thereby safeguarding the primary Mn target, the chloroplast, and ultimately conferring robust Mn tolerance in pecan.

Drought and cold crucially affect plant growth and distribution. Plants have evolved complex molecular mechanisms to adapt to such adverse environmental conditions. This study examines two Elymus sibiricus (Es) germplasms differing in resilience to these stresses. Analyzing physiological responses and gene expression changes under drought and cold, it reveals the similarities and differences in their molecular mechanisms that underlie these responses. The results indicate that both drought stress and cold stress severely damage the integrity of the cell membrane in Es. Notably, under cold stress, the accumulation of osmotic regulation substances in Es is more significant, which may be related to the regulation of carbohydrate metabolism (CM)-related genes in cold environments. Furthermore, the response to oxidative stress triggered by cold stress in Es is partially inhibited. The enrichment analysis showed that the DEGs responsive to drought stress in Es were mainly related to the pathway of photosynthesis, whereas the DEGs responsive to cold stress were more associated with the protein processing in endoplasmic reticulum (PPER), highlighting distinct molecular responses. In addition, we discovered that the abscisic acid (ABA) signaling transduction plays a dominant role in mediating the drought resistance mechanism of Es. We have identified 86 key candidate genes related to photosynthesis, Phst, CM, and PPER, including 5 genes that can respond to both drought and cold stress. This study provides a foundation for the molecular mechanisms underlying cold and drought resistance in Es, with insight into its future genetic improvement for stress resistance.

Pyrus sinkiangensis, a crucial economic fruit tree in Xinjiang, China, experiences winter hardiness that significantly influences its yield and fruit quality. This study aimed to investigate the role of PsHB7/12 in cold resistance of Pyrus sinkiangensis and its regulation of abscisic acid (ABA) signaling. Through physiological assessments and transcriptome analysis, we identified a peak expression of PsHB7/12 in January, which was strongly induced by ABA. We found a correlation between ABA concentrations and changes in water content and soluble protein levels during overwintering process. Further analysis of yeast one-hybrid and the luciferase assay revealed that PsHB7/12 was involved in the negative regulation of ABA signal by inhibiting the expression of PsPYL4. Additionally, the overexpression of the PsHB7/12 may have complex effects on ABA signaling through the modulation of expression of members of the PsPP2Cs family. In summary, PsHB7/12 regulates the ABA signaling pathway through a negative feedback mechanism. These findings reveal the critical role of PsHB7/12 in cold stress adaptation in Pyrus sinkiangensis and provide new molecular markers for breeding stress-resistant fruit trees.