Physiologia plantarum最新文献

Steryl esters (SE) are a storage pool of sterols that accumulates in cytoplasmic lipid droplets and helps to maintain plasma membrane sterol homeostasis throughout plant growth and development. Ester formation in plant SE is catalyzed by phospholipid:sterol acyltransferase (PSAT) and acyl-CoA:sterol acyltransferase (ASAT), which transfer long-chain fatty acid groups to free sterols from phospholipids and acyl-CoA, respectively. Comparative mass spectrometry-based metabolomic analysis between ripe fruits and seeds of a tomato (Solanum lycopersicum cv Micro-Tom) mutant lacking functional PSAT and ASAT enzymes (slasat1xslpsat1) shows that disruption of SE biosynthesis has a differential impact on the metabolome of these organs, including changes in the composition of free and glycosylated sterols. Significant perturbations were observed in the fruit lipidome in contrast to the mild effect detected in the lipidome of seeds. A contrasting response was also observed in phenylpropanoid metabolism, which is down-regulated in fruits and appears to be stimulated in seeds. Comparison of global metabolic changes using volcano plot analysis suggests that disruption of SE biosynthesis favours a general state of metabolic activation that is more evident in seeds than fruits. Interestingly, there is an induction of autophagy in both tissues, which may contribute along with other metabolic changes to the phenotypes of early seed germination and enhanced fruit tolerance to Botrytis cinerea displayed by the slasat1xslpsat1 mutant. The results of this study reveal unreported connections between SE metabolism and the metabolic status of plant cells and lay the basis for further studies aimed at elucidating the mechanisms underlying the observed effects.

Calcium ions (Ca²⁺) are important second messengers and are known to participate in cold signal transduction. In the current study, we characterized a Ca²⁺-binding protein gene, VamCP1, from the extremely cold-tolerant grape species Vitis amurensis. VamCP1 expression varied among organs but was highest in leaves following cold treatment, peaking 24 h after treatment onset. VamCP1 was found to localize to the plasma membrane and nucleus and the gene showed transcriptional autoactivation activity. Overexpression of VamCP1 in Arabidopsis thaliana and grapevine (V. vinifera) resulted in transgenic plants that were more tolerant to cold stress than the wild type. This correlated with reduced accumulation of reactive oxygen species (ROS), elevated activity of antioxidant enzymes and proline content, as well as lower levels of malondialdehyde and electrolyte leakage. Additionally, the expression of genes related to cold tolerance, including C-repeat binding factors (CBF) and cold-regulated (COR) genes, was higher in the transgenic lines. Taken together, our results indicate that overexpression of VamCP1 enhanced cold tolerance in plants by promoting the upregulation of genes related to cold tolerance and scavenging of excessive ROS. These findings provide a foundation for the molecular breeding of cold-tolerant grapevine.

Salt is a major abiotic factor significantly affecting plant growth and development. Alfalfa (Medicago sativa L.), a crucial perennial crop for livestock feed, shows significant differences in salt tolerance among different varieties. This study aimed to comprehensively evaluate the salt tolerance of 30 varieties of alfalfa under salt stress (0, 150, and 300 mmol L^-1 NaCl). It showed that shoot height (SH), root length (RL), shoot fresh weight (SFW), and root fresh weight (RFW) were decreased by 37.68%, 35.83%, 43.79% and 48.86%, respectively, under high salt stress. Photosynthesis-related parameters, including chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (TChl), and carotenoids (Car) contents of all varieties were decreased by 50.13%, 43.73%, 48.17% and 60.86%, respectively, and minimum inhibition of photosynthetic pigment contents was observed in the variety Salsa. The changes of antioxidant enzymes in different alfalfa varieties were also found under salt stress. For example, the APX of Sardi 7 decreased by 641.84%, while the APX of Phabulous decreased by 88.33% compared to the non-treated controls. Principal component analysis (PCA) identified five major variables: Car, TChl, APX, Chl a, and POD. Finally, each variety's comprehensive tolerance membership function values were calculated by the membership function method, and the 30 varieties were classified into four categories by cluster analysis. Our findings indicate that Sardi 7, Salsa, Gannong No.8, Daye, and Instinct are alfalfa salt-tolerant varieties. Our study provided baseline information on the response of alfalfa varieties to different salinity levels, which will help select or breed salt-tolerant varieties.

Understanding the role and mode of action of nutrient transporters requires information about their dynamic associations with plant membranes. Historically, apoplastic nutrient export has been associated with proteins localized at the plasma membrane (PM), while the role of endomembrane localization has been less explored. However, recent work on the PHOSPHATE 1 (PHO1) inorganic phosphate (Pi) exporter demonstrated that, although primarily localized at the Golgi and trans-Golgi network (TGN) vesicles, PHO1 does associate with the PM when clathrin-mediated endocytosis (CME) was inhibited, supporting a mechanism for Pi homeostasis involving exocytosis. We explored whether CME inhibition can identify other transporters that, although primarily localized at Golgi/TGN at steady-state level, also transit via the PM and are potentially involved in export via exocytosis. We found that, similar to PHO1, Golgi-localized transporters NA EFFLUX TRANSPORTER1 (NAET1) and METAL TOLERANCE PROTEIN11 (MTP11) relocate to the PM when CME is inhibited, both transiently in Nicotiana benthamiana and conditionally in Arabidopsis thaliana. Such PM re-localization of transporters upon CME inhibition is specific, since it does not occur with several other Golgi-associated transporters, including MTP5 and BIVALENT CATION TRANSPORTER 3 (BICAT3), as well as resident Golgi/TGN membrane proteins, such as α-1,2-MANNOSIDASE I (Man1) and VESICLE TRANSPORT V-SNARE 12 (VTI12). Additionally, we observed that NAET1, MTP11 and PHO1 all partially co-localize to vesicles. Overall, our study supports a role for synaptic-like vesicle-mediated exocytosis for both NEAT1 and MTP11 in nutrient transport in plants and highlights the importance of assessing the transient localization of Golgi/TGN proteins to the PM.

Salt stress disturbs plant growth and photosynthesis due to its toxicity. The ice plant Mesembryanthemum crystallinum is a highly salt-tolerant facultative crassulacean acid metabolism (CAM) plant. However, the genetic basis of the salt tolerance mechanisms in ice plants remains unclear. In this study, we constructed a chromosome-level whole-genome sequence of the ice plant and performed transcriptome analysis of the effects of salt treatment on the leaves. After 24-hour 500 mM NaCl treatment to the roots, 1100 and 1394 genes, including CAM pathway, glycolysis, and inositol metabolism, were up- and down-regulated in the leaves, respectively. Salt treatment also influenced the abscisic acid (ABA) signaling components, including genes from the PYRABACTIN RESISTANCE1 (PYR1) family and the PROTEIN PHOSPHATASE 2CA (PP2CA) family. We detected the induction of the genes encoding various ion transporters after salt treatment. The expression of most v-ATPase subunits is induced, leading to vacuolar acidification, which facilitates sodium ion sequestration in the vacuoles. Additionally, some genes encoding metal ion transporters, including the genes from the ZIP family and NRAMP family, were induced by salt treatment, accompanied by the accumulation of iron, zinc, and copper ions in the leaves. Cis-motif enrichment analysis revealed that ABRE-like motifs and MYB-binding-like motifs were enriched in the upstream sequences of genes that were either up-regulated or down-regulated by salt. In conclusion, this study highlights how salt treatment induces drastic and rapid transcriptomic changes and unveils the ice plant's genomic foundation. Our resources provide further insights into the regulation of salt tolerance in the ice plants.

Ensuring food security is one of the main challenges related to a growing global population under climate change conditions. The increasing soil salinity levels, drought, heatwaves, and late chilling severely threaten crops and often co-occur in field conditions. This work aims to provide deeper insight into the impact of single vs. combined abiotic stresses at the growth, biochemical and photosynthetic levels in Arabidopsis thaliana (L.). Reduced QY max was recorded in salinity-stressed plants, NPQ increased in heat and salinity single and combined stresses, and qP decreased in combined stresses. MDA and H₂O₂ content were consistently altered under all stress conditions, but higher values were recorded under salinity alone and in combination. Salinity alone and in stress combinations (especially with cold) provided a stronger hierarchical effect. Despite glycine and GABA osmolytes not significantly changing, proline highlighted the hierarchically stronger impact of salinity, while glycine-betaine was decreased under drought combinations. Untargeted metabolomics pointed out distinct metabolic reprogramming triggered by the different stress conditions, alone or in combination. Pathway analysis revealed that abiotic stresses significantly affected hormones, amino acids and derivates, and secondary metabolites. Flavonoids accumulated under drought (alone and combined with heat and cold stresses), while N-containing compounds decreased under all combined stresses. Looking at the interactions across the parameters investigated, antagonistic, additive, or synergistic effects could be observed depending on the biochemical process considered. Notwithstanding, these results contribute to delving into the impact of various stress combinations, hierarchically highlighting the stress-specific effects and pointing out different combinations.

Drought and nutrient-poor soils can increase the invasive potential of non-native species, further changing the ecosystems they invade. The high adaptability of these alien species, especially in their efficient use of resources, improves their resilience against abiotic stress. Here, we evaluated the response of the North American Quercus rubra L. (RO) and the European Quercus robur L. (EO) oak species to drought and nutrient scarcity as single and combined factors. Both species were grown under well-watered or alternating short dry-wet phases, with or without the addition of phosphorous (P) and labelled nitrogen (N). Leaf gas exchanges and stem water potential were measured; moreover, leaf chemical characterization was carried out. Under concurrent low fertility and drought, both species reduced gas exchanges and stem water potential, although RO recovery was faster than EO. Nutrient inputs did not modulate RO's physiological response; however, P supply increased its uptake of the more available N forms (¹⁵NH₄ ¹⁵NO₃). The different leaf contents of N and P demonstrated that EO has lower nutrient use efficiency compared to RO. Nevertheless, P addition significantly mitigated the drought effects on EO, highlighting the crucial role of this nutrient in aiding EO's recovery under stress conditions. RO invasive potential may be linked to its superior adaptability and resource-use efficiency under combined abiotic stress. Nevertheless, EO competitiveness can be improved through targeted nutrient management.

Plant-growth-promoting microorganisms are extensively studied and employed as alternatives to toxic agrochemicals to enhance plant health. However, one of the main concerns regarding their use is their limited capacity to colonize plant tissues after initial application. Understanding the molecular mechanisms involved during plant colonization could help to develop strategies to improve the efficacy of beneficial microbes in the field. Polysaccharides, including fructans, may be of particular interest since they have been shown to promote cellular and morphological changes in bacteria from the genus Bacillus that are typically associated with improved root colonization, such as increased motility and biofilm reinforcement. The potential role of fructans as signalling molecules affecting plant-microbe interactions is discussed in the context of plant root colonization with a focus on the model organism Bacillus subtilis, a well-characterized rhizobacterium. First, the molecular processes underlying B. subtilis cell differentiation are explained and connected to plant root colonization. Secondly, we explore how fructans, in particular inulin and levan, may interfere during these processes. These views call for further research into the putative role of inulin and levan-type fructans as microbial signalling molecules, with the aim of developing beneficial microbial networks in the rhizosphere.

Combined cold and high moisture stress (CHS) is a prevalent abiotic stress during maize sowing in northeast China, severely affecting the growth of seedlings and seed germination. However, the mechanism underlying seed growth responses to CHS remains unclear. We used Jidan441 (JD441, CHS-resistant) and Jidan558 (JD558, CHS-sensitive) as experimental materials. Treatments of 5-day cold (4°C, CS), high moisture (25%, gravimetric water content, HH), and CHS were initiated at sowing, followed by a return to normal growth conditions (20°C during light/ 15°C during dark, 15%) at 7 days after sowing (DAS). CS, HH, and CHS decreased seed root length and surface area. The reduction in root length and surface area in JD441 due to CHS was less severe than in JD558. We found that the difference between CHS and control in JD441was less than that in JD558 at transcriptional and metabolic levels at 7 DAS. After CHS removal, JD441 exhibited a greater increase in α-amylase activity and antioxidant content than JD558, which facilitated starch decomposition and the rapid removal of O₂ ^- and H₂O₂ in seeds. The rapid recovery of soluble sugar and soluble protein in JD441 helped maintain osmotic balance. Amino acids and genes related to amino acid metabolism were upregulated in response to combined stress in JD441, whereas they were downregulated in JD558. In conclusion, the stress tolerance of JD441 was attributed to its efficient recovery ability from CHS. This study provides a scientific foundation for exploring seed stress tolerance pathways and developing cold and high-moisture-tolerant hybrids.

Chrysanthemum (Chrysanthemum morifolium Ramat.) is a short-day plant, and flowering is stimulated when the photoperiod is shorter than a variety-specific threshold (critical day length). In Japan, summer-to-autumn-flowering cultivars (SA-cvs.) flower from July to September. Little research has been conducted to understand why SA-cvs. bloom earlier than autumn-flowering cultivars (A-cvs.). We conducted a comparative study of the relationship between the photoperiodic response of flowering and the gene expression of florigen FLOWERING LOCUS T-like 3 (FTL3) and antiflorigen anti-florigenic FT/TFL1 (AFT). SA-cvs. had a longer critical day length than A-cvs. However, in both groups, a decrease in AFT and increase in FTL3 were consistently observed below the critical day length when flowering was promoted. The opposite responses (less flowering, low FTL3, and high AFT) were observed for longer than the critical day lengths. This indicated that flowering in SA-cvs. was controlled by the regulation of AFT/FTL3 expression, similar to that in A-cvs. Next, we studied the mechanism that causes a variation in critical day lengths. In SA-cvs., the photosensitive phase, which occurs at night, occurs earlier than that in A-cvs. This indicates a variation in the endogenous time-keeping mechanism. This was supported by the fact that the circadian rhythmicity of leaf movement was weaker in SA-cvs. than that in A-cvs. Thus, variation in the endogenous time-keeping mechanism may cause a longer critical day length and earlier flowering time in SA-cvs.