Plant Physiology and Biochemistry最新文献

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.

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.

To improve the selenium (Se) uptake in grapes, the effects of arbuscular mycorrhizal fungi (AMF) on the Se accumulation in grapevines were studied under a soil Se concentration of 5 mg/kg, and the transcriptome and metabolome sequencing were used to elucidate the regulatory mechanism of AMF on Se accumulation. AMF initially decreased the biomass of grapevines, but later increased the biomass. Moreover, AMF enhanced the activities of Se metabolism enzymes (adenosine triphosphate sulfurylase, adenosine 5'-phosphosulfate reductase, serine acetyltransferase, and cysteine methyltransferase) and the Se concentration in grapevines. Compared to Se treatment alone, AMF resulted in a 20% increase in root Se concentration and a 21% increase in shoot Se concentration 60 days after treatment. Transcriptome and metabolome analyses revealed that AMF up-regulated the expression levels of inorganic phosphate transporter proteins 1-11 and down-regulated the expression levels of ABC transporter family members, water channel proteins, and sulfur transporter proteins in grapevines. In addition, AMF elevated the levels of hesperidin, naringenin, apigenin, neohesperidin, pine sapogenin, and rutin in grapevines. Therefore, AMF can enhance Se accumulation in grapes by modulating the phosphate transport pathway and the biosynthesis of secondary metabolites involved in the phenylpropane biosynthesis pathway, flavonoid biosynthesis pathway, and flavonoid and flavonol biosynthesis pathway.

Chitinases are enzymes that hydrolyze β-1,4-glycosidic bonds in chitin. Previous studies have shown that several chitinases accumulated significantly in A. mongolicus, suggesting that chitinases might participate in the adaptation to winter climate in Ammopiptanthus mongolicus. Here, we analyzed the evolution and expression patterns of the chitinase gene family in A. mongolicus and investigated the function and regulatory mechanisms of the AmChi7 gene in response to abiotic stress. The chitinase gene family in A. mongolicus comprises 27 members, many of which arose through formed by tandem and segmental duplication. Several chitinase genes, including AmChi7 gene, were significantly upregulated in winter. Overexpression of AmChi7 gene enhanced the tolerance of yeast to freeze-thaw cycle and osmotic stress, and enhanced the tolerance of transgenic Arabidopsis to low-temperature and drought stress. Furthermore, AmWRKY59, a MeJA-induced transcription factor, bound to the W box element in the AmChi7 gene promoter, activating its expression in winter. It is speculated that chitinase AmChi7 accumulation in winter enhances adaptation to temperate winter climates in A. mongolicus. This study expands our understanding of the biological functions of chitinases and provides insights into the molecular mechanisms underlying winter climate adaptation in A. mongolicus.

Cold stress is one of the most serious abiotic stresses that affects the growth and yield in rice. However, the molecular mechanism by which abscisic acid (ABA) regulates plant cold stress tolerance is not yet clear. In this study, we identified a member of the OsNCED (9-cis-epoxycarotenoid dioxygenase) gene family, OsNCED5, which confers cold stress tolerance in rice. OsNCED5 encodes a chloroplast-localized ABA biosynthetic enzyme and its expression is strongly induced by cold stress. Disruption of OsNCED5 by CRISPR/Cas9-mediated mutagenesis led to a significant decrease in ABA content and exhibited significant reduced cold stress tolerance at the seedling stage. Exogenous ABA restored the cold stress tolerance of the osnced5 mutants. Overexpression of OsNCED5 gene significantly improved the cold stress tolerance of rice seedlings. Moreover, OsNCED5 mainly regulates cold stress tolerance through regulating reactive oxygen species (ROS) homeostasis. Taken together, we identified a new OsNCED regulator involved in cold stress tolerance, and provided a potential target gene for enhancing cold stress tolerance in rice.

Cold stress significantly limits the growth and yield of tea plants (Camellia sinensis (L.) O. Kuntze), particularly in northern China, may lead to huge economic losses. Glycine betaine (GB), an osmotic regulator, is widely applied in crop resistance to abiotic stress. This study investigates the role of GB and its biosynthetic enzyme CsBADH in enhancing cold tolerance in tea plants. Two cultivars, 'Shuchazao' (cold-resistant) and 'Baiye 1' (cold-sensitive), were subjected to low temperature stress (0 °C). GB accumulation was measured, revealing that 'Shuchazao' exhibited 1.4-fold higher GB levels than 'Baiye 1', suggesting a link between higher GB accumulation and cold tolerance. Exogenous GB treatment improved cold resistance, especially in the cold-sensitive cultivar 'Baiye 1'. The CsBADH gene, a key enzyme in GB biosynthesis, was cloned and expressed in Escherichia coli, confirming its activity. Transgenic Arabidopsis thaliana, Nicotiana tabacum, and C. sinensis plants overexpressing CsBADH showed increased GB levels (1.5- to 2.4-fold), proline content, peroxidase (POD) activities, and enhanced cold tolerance, while silencing CsBADH decreased GB accumulation and cold resistance. These findings demonstrate that CsBADH plays a critical role in cold stress response by promoting GB accumulation, offering potential strategies for improving the resilience of tea and other leaf crops to cold stress.