Physiologia plantarum最新文献

Melatonin is a potentially active signaling molecule and plays a crucial role in regulating the growth and development of plants under stress conditions, alleviating oxidative damage, enhancing antioxidant defence mechanisms and regulating ion homeostasis. This study examined the effects of exogenous melatonin application on leaf biomass, ion concentrations, betalains, phenolic acid and endogenous melatonin contents comparing red beet (Beta vulgaris L. 'Ruby Queen' and 'Scarlet Supreme') and white beet ('Rodeo' and 'Ansa') cultivars under increasing salinity levels of 50, 150, and 250 mM NaCl. Exogenous melatonin increased salinity-induced reductions in fresh and dry weights and osmotic potential in leaves. Na⁺ concentrations rose significantly with increasing salinity, but cultivar-specific decreases were observed in K⁺ and Ca²⁺ concentrations. Additionally, melatonin application improved betalain, betanin and neobetanin contents induced by salt stress. Furthermore, melatonin application caused salt stress and cultivar-specific changes in phenolic acid contents e.g., ferulic acid, sinapic acid, or m-coumaric acid, in soluble free, ester- and glycoside-conjugated and cell wall-bound forms. In addition, antioxidant enzyme activities and compound contents increased significantly in the beets and were subsequently lowered in a cultivar-specific manner by salt stress + melatonin treatment. The current findings indicate that exogenous melatonin improved plant stress tolerance suppressing reactive oxygen species levels, increasing the antioxidant enzyme activities and compound contents and reducing the levels of Na⁺, maintaining an ionic homeostasis in the selected red and white sugar beet cultivars. It appears that melatonin application may help improve cultivar-specific salt tolerance by enhancing ion homeostasis and betalain and phenolic acid production levels in beets.

Grapevine (Vitis vinifera L.) is the world's third most valuable horticultural crop, and the current environmental scenario is massively shifting the grape cultivation landscape. The increase in heatwaves and drought episodes alter fruit ripening, compromise grape yield and vine survival, intensifying the pressure on using limited water resources. ABA is a key phytohormone that reduces canopy transpiration and helps plants to cope with water deficit. However, the exogenous application of ABA is impractical because it suffers fast catabolism, and UV-induced isomerization abolishes its bioactivity. Consequently, there is an emerging field for developing molecules that act as ABA receptor agonists and modulate ABA signaling but have a longer half-life. We have explored the foliar application of the iSB09 and AMF4 agonists in the two grapevine cultivars cv. 'Bobal' and 'Tempranillo' to induce an ABA-like response to facilitate plant adaptation to drought. The results indicate that iSB09 and AMF4 act through the VviPYL1-like, VviPYL4-like, and VviPYL8-like ABA receptors to trigger stomatal closure, reduce plant transpiration, and increase water use efficiency. Structural and bioinformatic analysis of VviPYL1 in complex with ABA or these agonists revealed key structural determinants for efficient ligand binding, providing a mechanistic framework to understand receptor activation by the ligands. Physiological analyses further demonstrated that iSB09 has a more sustained effect on reducing transpiration than ABA, and agonist spraying of grapevine leaves protected PSII during drought stress. These findings offer innovative approaches to strengthen the vine's response to water stress and reduce plant consumptive water use under limited soil water conditions.

Plant-growth-promoting (PGP) endophytic bacteria are beneficial microorganisms that can help plants withstand biotic stress caused by fungal phytopathogens. In the present study, 78 endophytic bacterial isolates were isolated from chilli (Capsicum annuum L.). A potent isolate with several PGP attributes and better inhibition against Agroathelia rolfsii was selected and identified as Bacillus amyloliquefaciens using 16S rDNA homologies. Phosphate solubilization (65.9 μg ml^-1), nitrogen fixation, production of IAA (9.77 to 24.45 μg ml^-1), ammonia, ACC deaminase, siderophore, and hydrolytic enzymes were among the PGP traits shown by the strain SS_CR10. Furthermore, the strain demonstrated the ability to colonize roots. It significantly improved the plant's developmental traits, such as fresh and dry weight, photosynthetic pigments, and root and shoot length. LC-MS analysis and PCR amplification of lipopeptide genes also showed that surfactin, iturin, and bacilysin lipopeptides were present. Following treatments with lipopeptide extract and bacterial suspension, A. rolfsii mycelia showed severe deformation and cell death, as seen by live dead staining by fluorescent microscopy and scanning electron microscopy (SEM). Finally, the upregulation of defense-related genes CaPR1, CaPR2, and CaPR4 after bacterial treatment confirmed the induction of systemic resistance. In conclusion, this study shows how strain SS_CR10 might be useful for promoting plant growth in chilli and controlling A. rolfsii in an eco-friendly way, which would protect the health of the soil.

Drought is a significant global environmental stress. Biostimulants offer a sustainable solution to enhance crop tolerance and mitigate productivity losses. This study assessed the impact of foliar application of ERANTHIS®, a biostimulant derived from the algae Ascophyllum nodosum and Laminaria digitata and yeast extracts, on tomato plants under mild water stress. Evaluations were conducted at 5 and 24 hours after the third treatment. Under optimal water conditions, the biostimulant showed a priming effect, with an early increase of stress markers and a timing-specific modulation of ROS non enzymatic and enzymatic ROS scavenging activities. Under drought stress, the biostimulant later decreased stress markers, by aligning the majority of analyzed ROS scavengers closer to levels in well-irrigated plants. Transcriptome analysis using RNA-seq data revealed differentially expressed genes (DEGs) and multivariate data highlighted groups of co-regulated genes (k-means clustering). Genes involved in water channel activity, transcription regulator activity, and oxidoreductase activity were significantly modulated. Cluster analysis identified distinct gene clusters influenced by the biostimulant under optimal conditions, including early responses (cell wall modification, hormone signaling) and late responses (RNA modification, nutrient uptake process). Under water stress, early responses involved actin filament organization and MAPK signaling, while late responses were related to plasma membrane components and cell wall organization. This study, integrating biochemical and transcriptomic data, provides a comprehensive understanding of how a biostimulant primes plants under optimal conditions and mitigates water stress effects, offering valuable insights for sustainable agriculture.

Carbonic anhydrases (CAs) are the main enzymes handling bicarbonate in the different cell compartments. This study analyses the expression of CAs in roots of Arabidopsis thaliana demes differing in tolerance to bicarbonate: the tolerant A1_(C+) deme and the sensitive deme, T6_(C-). Exposure to 10 mM NaCl caused a transient depolarization of the root cell membranes, and in contrast, the supply of 10 mM NaHCO₃ caused hyperpolarization. This hyperpolarization was much stronger in A1_(C+) than in T6_(C-). Acetazolamide (AZ), a specific inhibitor of CAs, abolished the hyperpolarizing effect in A1_(C+), indicating the implication of CAs in this fast membrane response. The time-dependent (3 to 72 h) expression profiles of 14 CAs in roots of A1_(C+) and T6_(C-) exposed to either control (0 mM NaHCO₃, pH 5.9), or bicarbonate (10 mM NaHCO₃,pH 8.3) conditions revealed a bicarbonate specific upregulation of BCA4.1 (from 3 to 12 h) in A1_(C+). Contrastingly, in T6_(C-) BCA4.1 was downregulated by NaHCO₃. Exclusively in A1_(C+), the enhanced expression of BCA4.1 under bicarbonate was parallelled by an increase of PIP1,3, SLAH1, SLAH3, AHA2, and FRO2 gene expression levels. Under HCO₃ ^- exposure, a bca4 knockout mutant had a lower number of lateral roots, lower root diameters, and higher root lipid peroxidation than the WT. These results indicate that bicarbonate-induced root membrane hyperpolarization is the fast (minutes) initial signalling event in the tolerance response. This is followed by the specific upregulation of BCA4.1 and genes involved in H₂O and CO₂ transport, apoplast acidification, and iron acquisition.

Caffeic acid-3-O-methyltransferase (COMT) serves as the final pivotal enzyme in melatonin biosynthesis and plays a crucial role in governing the synthesis of melatonin in plants. This research used bioinformatics to analyze the phylogenetic relationships, gene structure, and promoter cis-acting elements of the upland cotton COMT gene family members， which it identified as the key gene GhCOMT33D to promote melatonin synthesis and responding to Cd²⁺ stress. After silencing GhCOMT33D through virus-induced gene silencing (VIGS), cotton seedlings showed less resistance to Cd²⁺ stress. Under Cd²⁺ stress, the melatonin content in the silenced plants significantly decreased, while ROS, MDA, and proline accumulated in the plant cells. The stomatal aperture of the leaves was reduced, hindering normal photosynthesis, leading to cotton leaves withering and yellowing, and epidermal cells becoming twisted and deformed, with a large number of gaps appearing. The non-silenced plants had a significantly higher melatonin content and were in better condition, providing important evidence for further research on how plant melatonin enhances the Cd²⁺ resistance of cotton and its regulatory mechanisms.

It is essential for the survival of grapevines in cool climate viticultural regions where vines properly acclimate in late fall and early winter and develop freezing tolerance. Climate change-associated abnormities in temperature during the dormant season, including oscillations between prolonged warmth in late fall and extreme cold in midwinter, impact cold acclimation and threaten the sustainability of the grape and wine industry. We conducted two experiments in controlled environment to investigate the impacts of different temperature regimes on cold acclimation ability in endodormant grapevine buds through a combination of freezing tolerance-based physiological and RNA-seq-based transcriptomic monitoring. Results show that exposure to a constant temperature, whether warm (22 and 11°C), moderate (7°C), or cool (4 and 2°C) was insufficient for triggering cold acclimation and increasing freezing tolerance in dormant buds. However, when the same buds were exposed to temperature cycling (7±5°C), acclimation occurred, and freezing tolerance was increased by 5°C. We characterized the transcriptomic response of endodormant buds to high and low temperatures and temperature cycling and identified new potential roles for the ethylene pathway, starch and sugar metabolism, phenylpropanoid regulation, and protein metabolism in the genetic control of endodormancy maintenance. Despite clear evidence of temperature-responsive transcription in endodormant buds, our current understanding of the genetic control of cold acclimation remains a challenge when generalizing across grapevine tissues and phenological stages.

Irrigation of grasses dominates domestic water use across the globe, and better understanding of water use and drought resistance in grasses is of undeniable importance for water conservation. Breeding programs have released cultivars with improved drought resistance, but the underlying mechanisms remain unknown. We sought to characterize the mechanisms driving drought resistance in four zoysiagrass cultivars (Lobo, Zeon, Empire, and Meyer) reported to exhibit contrasting levels of drought resistance. A dry-down was performed through deficit irrigation until 70% decline in evapotranspiration. All cultivars exhibited similar drought avoidance as they dehydrated similarly throughout the drought. Lobo and Zeon, however, exhibited a 70% decline in evapotranspiration two to three days after Empire and Meyer, thus experiencing lower water potentials. Regarding drought tolerance, Lobo and Zeon maintained higher normalized difference vegetation index (NDVI) and lower perceived canopy mortality at higher dehydration levels than Empire and Meyer. We use "perceived" because visual assessments of canopy mortality are influenced by drought-induced leaf rolling. During the recovery, leaves rehydrated and unrolled, so the "actual" canopy mortality could be evaluated. All cultivars exhibited similar mortality on the first recovery day despite Lobo and Zeon experiencing more severe dehydration. Throughout the recovery, Lobo and Empire exhibited faster re-growth and showed the lowest canopy mortality, and Lobo exhibited the highest NDVI. The improved drought resistance of Lobo and Zeon results from greater dehydration tolerance rather than avoidance. This study has implications for lawn owners selecting the best cultivars and for breeding programs aiming at improving drought resistance of zoysiagrasses.

Description of aims and systems used: Olive (Olea europea L.) is one of the most economically important tree crops worldwide, especially for the countries in the Mediterranean basin. Given the economic and nutritional importance of the crop for olive oil and drupe production, we generated transcriptional atlases for the Greek olive cultivars "Chondrolia Chalkidikis" and "Koroneiki" which have contrasting characteristics in terms of fruit development, oil production properties, and use. Our analysis involved 14 different organs, tissue types, and developmental stages, including young and mature leaves, young and mature shoots, open and closed flowers, young and mature fruits (epicarp plus mesocarp), young and mature endocarps, stalks, as well as roots. The developed gene expression atlases and the associated resources offer a comprehensive insight into comparative gene expression patterns across several organs and tissue types between significant olive tree cultivars. The comparative analyses presented in this work between the "Koroneiki" cultivar, which performs better in olive oil production, and the "Chondrolia Chalkidikis," which grows larger fruits, will be essential for understanding the molecular mechanisms underlying olive oil production and fruit shape and size development. The developed resource is also expected to support functional genomics and molecular breeding efforts to enhance crop quality and productivity in olive trees.

Outline of data resources generated: The transcriptome data were generated using paired-end Illumina Next-Generation Sequencing technologies. The sequencing yielded approximately 13 million reads per sample for "Chondrolia Chalkidikis" and around 24 million reads per sample for "Koroneiki." The transcriptomes were comparatively analyzed to reveal tissue-specific and differentially expressed genes and co-expression gene modules within and between cultivars.

Summary of key results: The comparative analysis unveiled tissue-specific and differentially expressed genes within and between cultivars. Hierarchical gene clustering revealed intra- and inter-cultivar expression patterns, particularly for the endocarp and fruit tissues relevant to olive oil production and fruit development. Additionally, genes associated with oil production and fruit size/shape development, including those in fatty acid metabolism and developmental regulation, were identified.

Broader utility of the resource: To facilitate accessibility, the GrOlivedb (www.GrOlivedb.com) database was developed, housing the comprehensive transcriptomic data for all of the analyzed organs and tissue types per cultivar. This resource will be a useful molecular tool for future breeding studies in olive oil production and fruit development and a valuable resource for crop improvement.

Pyrabactin or Actin Resistance1/PYR1-Like/Regulatory Components of abscisic acid (ABA) Receptors (PYR/PYL/RCARs, referred to as PYLs) are direct receptors of ABA that function pivotally in the ABA-signaling pathway. Previously, we discovered that CmPYL7 was strongly upregulated by cold stress in oriental melon (Cucumis melo). In this study, we demonstrated that CmPYL7 was strongly induced by cold treatment (Cold), Cold+ABA, and Cold+fluridone (Flu, an ABA inhibitor) treatments, while the expression level of CmPYL7 under Cold+Flu is lower than that of cold treatment. Silencing CmPYL7 in oriental melon seedlings significantly decreased cold tolerance due to the reduced activities of antioxidant enzymes [superoxide dismutase (SOD); catalase (CAT), and ascorbate peroxidase (APX)] and the accumulation of H₂O₂, accompanied by higher electrolyte leakage and MDA content, but lower proline and soluble sugar content. In contrast, overexpressing CmPYL7 in Arabidopsis plants significantly increased cold tolerance owing to the enhanced activities of antioxidant enzymes (SOD, CAT, and APX) and limited H₂O₂, accompanied by lower electrolyte leakage and MDA content, but higher proline and soluble sugar contents. CmPYL7 was found to interact with CmPP2C24-like in vivo and in vitro, whose expression is downregulated under cold stress. Furthermore, silenced CmPP2C24-like in oriental melon plants significantly increased cold tolerance, exhibiting lower electrolyte leakage and MDA content and higher proline and soluble sugar contents. The activities of SOD, CAT, and APX were further enhanced and contents of H₂O₂ were significantly limited from increasing in TRV-CmPP2C24-like seedlings. These results demonstrated that CmPYL7 functions positively in the ABA-signaling pathway to regulate cold tolerance by interacting with CmPP2C24-like protein.