Environmental and Experimental Botany最新文献

In plants, alcohol dehydrogenases (ADHs) are involved in stress response, organ development, fruit ripening, and metabolite synthesis. However, little is known regarding ADH-encoding genes (ADHs) in Cucurbita moschata which is usually used as a rootstock for cucumber, melon, watermelon, and other cucurbit crops to resist soil-borne diseases and abiotic stresses. We identified 11 CmoADHs in the C. moschata genome that were unevenly distributed across seven chromosomes. These genes were predicted to encode stable cytoplasmic acidic proteins, sharing a low degree of identity with each other. The genes exhibited different intron–exon structures. Analysis of cis-acting regulatory elements showed that CmoADHs contain environmental stress-, hormone response-, light response-, and development/tissue specificity-related elements in their promoters. Expression pattern analysis revealed that CmoADH2, CmoADH3, CmoADH4, CmoADH9, CmoADH10, and CmoADH11 had the highest expression levels in the roots, which were significantly higher than those in the other tested tissues. These six genes may play important roles in the growth and development of roots, and in related abiotic stress responses. CmoADH1, CmoADH5, CmoADH6, CmoADH7, CmoADH8 had the highest expression in the apical region and could be involved in the differentiation of newly formed tissues. To study the role of CmoADHs in abiotic stress, salt, drought, low temperature, and ethephon treatments were performed. Under drought conditions, CmoADHs showed different expression trends. The expression levels of CmoADH1, CmoADH2, CmoADH3, and CmoADH9 increased significantly and peaked after 1 h of drought treatment, indicating that these four genes are more sensitive to drought stress. Under salt treatment, all CmoADHs showed a significant increase or decrease in expression within 6 h, except for CmoADH5 and CmoADH10, which were insensitive to salt treatment. The expression of most of the CmoADHs was significantly downregulated by low-temperature treatment. Ethephon treatment significantly induced the expression of all the CmoADHs, except CmoADH2, to different degrees within 12 h. CmoADH9 was found to be involved in root growth and drought stress resistance. Identification of these ADH genes can provide useful resources for conferring stress resistance in other economically important crops.

The intensification of droughts due to climate change is a global concern, and many plant species face increasing water deficits. Understanding the role of phenotypic plasticity in plant adaptation to these changing conditions is crucial. This research focuses on Bromopsis erecta, a dominant perennial grass in European and Mediterranean grasslands, to predict its potential adaptation to climate change. We assessed plants from shallow and deep soils (i.e., with contrasting water reserves) of a Mediterranean rangeland in southern France, and tested the effect of six years of experimentally increased summer drought compared to the ambient conditions on plant traits, survival and abundance. In both field and common garden experiments, we measured water-related traits, including static traits under non-limiting water conditions, and dynamic traits, such as rates of trait variation during drought. Trait plasticity was determined as a reaction norm to increasing soil water stress and was tested against changes in B. erecta abundance over the past decade, including the study period. Trait plasticity was detected only for leaf dry matter content (LDMC), revealing that the resource strategy of B. erecta became more conservative over less than a decade with higher LDMC and leaf thickness according to the plant economic spectrum. No plasticity was found for osmotic potential or specific leaf area. The variability of other traits was ascribed to the possible lagging effect of previous water stress and was associated more with soil depth than with previous summer drought intensity. The abundance decline of B. erecta, which dropped from 20 % to around 5 % in shallow soils, was not associated with the plasticity of LDMC but was positively correlated with variations in leaf base membrane damage, meaning unexpectedly, that plants exposed to the most severe summer drought also had the most sensitive leaf base membranes, a possible sign of maladaptive trait plasticity in the population. This key trait response reveals boundaries to the adaptive capacity of this perennial grass to survive pluri-annual drought.

Late embryogenesis abundant (LEA) proteins play a crucial role in determining how plants respond to abiotic stress. Nonetheless, the comprehensive characterization and function of the LEA gene family in Ammopiptanthus nanus, an endangered evergreen shrub plant that survived in harsh desert environments, are largely unknown. Through a comprehensive genome-wide investigation, we successfully identified 45 AnLEA genes in A. nanus and divided them into eight groups. AnLEAs have typical LEA domains, and the promoter analysis shows that they contain various cis-regulatory elements related to stress resistance. The diverse expression patterns of AnLEAs under different abiotic stress treatments suggest that they play an important role in responding to stress. Overexpression of AnLEA30 in tobacco significantly enhanced abiotic stress tolerance by effectively stabilizing and protecting membranes, scavenging reactive oxide species (ROS), and improving photosynthesis, demonstrating the potential for application of AnLEA30 in plant improvement.

Exogenous selenium (Se) addition can dynamically regulate the establishment of microbial communities, induce the expression of specific microbial functional genes, and affect the homeostasis of the soil-plant microenvironment. In this study, we used metagenomic and metabolomic analyses to investigate Se-mediated homeostatic changes and functional responses in the rhizosphere soil of rice seedlings. Results show that compared with the Cd set, selenium (1 mg/kg) Se content in the Soil and rice plant increased by 88.5 % and 99.1 %, respectively. Soil-fluorescein diacetate (S-FDA) hydrolyze enzymatic activity increased by 42.9 %, Rice on Cd enrichment coefficient increased by 71.1 %, but the transfer coefficient by 21.6 %, making a lot of cadmium ion stranded in the root, easing the toxicity of cadmium to plant. Metagenomic analysis revealed that Se bioaugmentation altered the structure and composition of the rhizosphere microbial community and induced remodeling of the rice rhizosphere microbiome. Increase the heavy metal resistance genes (cznA czcD, czcP, dltC, and CREM), nutrient cycling functional genes (atoB tktB, acs, sdhA, accA, ppdK, NRT, narB, nifD, napA, pstS, GlpQ, spoT, phoR, sucC) and heavy metal transport protein family (P-ATPase, CDF, ABC, and MIT) expression. It significantly improved the health of the rhizosphere microenvironment and alleviated soil hardening and nutrient deficiency caused by heavy metals. At the same time, in metabonomics analysis, The upregulated Differentially expressed metabolites (DEMs) were mainly in the Biosynthesis of siderophore group nonribosomal peptides, Sulfur metabolism, Ubiquinone and other terpenoid-quinone Biosynthesis, Cysteine, and methionine metabolism in enrichment significantly. The mediated reshaping of rhizosphere microorganism groups indicates that there is ane an advantage in the nutrient cycle. Also, the secondary metabolism and antioxidant capacity have significantly strengthened the ed, and the large strain caused by the death of heavy metals is a result of poor Soil. In addition, the Cyclic adenosine monophosphate (CAMP) signaling pathway was activated among the remodeling microbiomes, and the receptor protein inducer was upregulated, which activated the population response among the rhizosphere microbiomes and resulted in the overexpression of specific functional genes of each microbiome. By enhancing the resistance to heavy metals and nutrient cycling ability of the rhizosphere microbiome, the mobility and bioavailability of Cd ions were significantly reduced, the rhizosphere soil microenvironment health was improved, and the adaptability of rice to Cd stress was improved. This study reveals the Se of rice rhizosphere Cd-resistant bacteria mediating mechanisms; research for precise regulation of plant rhizosphere microorganism groups opens new avenues of research and offers a new way for crop production safety.

Chromium phytotoxicity results in relevant alterations to plant physiology, gene expression, and genomic DNA methylation at a transgenerational level. Herein, transcriptional responses of durum wheat (Triticum turgidum L.) to chronic chromium exposure were explored in roots and leaves by RNA-seq approach. Plants grown all the time in a hydroponic system supplemented with 2.5 and 10 µM hexavalent chromium were compared to unstressful control plants, assessing biomass and seed yield analyses after senescence. Then, transcriptomic analysis was performed with these plants kept under 10 µM chromium 50 days after the onset of exposure. The chromium concentrations used were considered the lowest dose sufficient to alter gene expression without impeding plant development, while the sampling time reflected the effects in the pre-harvest phase and long-lasting defense mechanisms. Root and leaf samples from plants kept under 10 µM chromium stress and from unstressful control plants were analyzed, generating 12 RNA-seq libraries. In total, 965 and 810 transcripts were found to be differentially expressed, respectively, in roots and leaves in response to 10 µM chromium stress. In roots, transcriptional changes were noted in the primary and secondary metabolism, redox homeostasis, protein modification, solute transport, nutrient uptake, and external stimuli responses. Meanwhile, the transcriptional changes in leaves were primarily found in the secondary metabolism, hormone-related pathways, chromatin modifications, cell division, protein modification and homeostasis, solute transport, and nutrient uptake. In particular, the metal uptake and translocation pathways were studied with greater emphasis to identify key proteins involved in chromium transport and compartmentalization. Furthermore, several genes involved in the biosynthesis of malate-derived organic acids, trace metal transport/detoxification/chelation, and vacuolar compartmentalization were linked to primary defense responses, and some of them were also associated with two putative gene clusters. Therefore, these genes and gene clusters are suggested as valuable biotechnological targets for future proof-of-concept studies aimed at genetic engineering of durum wheat to improve plant tolerance to chromium exposure.

The FtsH (Filamentous temperature sensitive H) proteases, known for their crucial roles in protein quality control and maintaining the integrity of photosynthetic machinery, have emerged as key regulators of stress responses in plants. Our previous study revealed the overexpression of MsFtsH8, an FtsH gene from alfalfa (Medicago sativa L.), confers salt stress tolerance to the plant. By comparing the proteomic profiles of MsFtsH8-overexpressing alfalfa and wild type under salt stress conditions, we elucidate the molecular pathways underlying MsFtsH8-mediated salt stress resilience. We identified 730 differentially expressed proteins (DEPs) in MsFtsH8-overexpressing alfalfa under salt stress, compared to 498 DEPs in wild type alfalfa under the same growth condition. Our results reveal significant alterations in the expression of proteins involved in the photosynthetic system, consistent with the chloroplast subcellular localization of MsFtsH8. Specifically, MsFtsH8 overexpression stabilizes key components of Photosystem II (PSII) and enhances electron transport processes, leading to increased photosynthetic efficiency and oxidative photodamage repair capacity under salt stress. Moreover, MsFtsH8-overexpressing alfalfa exhibits elevated levels of antioxidative enzymes, further mitigating oxidative damage induced by high salinity. These findings deepen our understanding of the regulatory role of MsFtsH8 in salt stress response and highlight its potential for improving crop resilience under adverse environmental conditions.

Brassinosteroid (BR) plays a crucial role in plant growth, development and response to abiotic stress. However, the mechanism by which BR regulates the response of potato plants to phosphorus deficiency stress is still largely unknown. In this work, the effects of BR on the growth of potato plants under phosphorus deficient condition were investigated. Exogenous BR application mitigated the growth inhibition caused by phosphorus deficiency stress. Transcriptomic analyses revealed that BR application altered the expression of genes involved in mitogen-activated protein kinase (MAPK) signaling pathway, plant hormone signal transduction, and nitrogen and phosphorus metabolisms under phosphorus deficient condition. Further gene ontology (GO) analysis indicated a significant enrichment of genes associated with reactive oxygen species scavenging process. Ectopic expression of potato brassinosteroid synthesis gene StCYP85A1 in Arabidopsis improved the resistance of transgenic plants to phosphorus deficiency stress, as indicated by the increased germination greening ratio and root growth. Quantitative real time PCR and antioxidant enzyme activity analysis revealed that ectopic expression of StCYP85A1 altered the expression of genes related to nitrogen and phosphorus metabolism, and promoted antioxidant enzyme activity in transgenic plants. These findings indicated that BR improved the tolerance of potato plants to phosphorus deficiency stress by regulating nutrient homeostasis and reactive oxygen species scavenging.

This study provided evidence at the first time showing that root inoculation with the plant growth-promoting rhizobacteria Paraburkholderia sp. GD17 improved the growth and tolerance to Cd stress in Chinese cabbage seedlings. Under normal conditions, the shoot fresh and dry weight of GD17-inoculated 30-day-old plants increased by about 29 % and 33 %, and their root fresh and dry weight by 104 % and 67 %, respectively, compared with their non-inoculated partners. The GD17-mediated growth promotion could be attributed to its facilitating influence on plant acquisition of nutrient elements and photosynthetic efficiency, and decreasing abscisic acid production. Under Cd stress, an effective alleviation in Cd-induced growth inhibition was observed in GD17 plants relative to non-inoculated control, suggesting that the root inoculation with GD17 played a systemic protective role. The Cd concentration in plant aerial tissues was comparable between GD17 plants and non-inoculated ones, but it was substantially decreased in GD17 plant roots. In response to Cd, GD17-inoculated plants generally showed a stronger ability to absorb and transport nutrient elements to shoots. The GD17-conferred plant tolerance to Cd was also associated with an increased antioxidative capacity companied by declined oxidative damage, optimal levels of phytohormones, increased flavonoid synthesis as indicated by significantly upregulated expression of related genes and activity of phenylalanine ammonia-lyase. Additionally, root inoculation with GD17 effectively mitigated the Cd-induced decline in photosynthetic efficiency. Collectively, this study firstly showed that GD17-conferred growth-promotion and Cd-tolerance in Chinese cabbage was correlated with multiple regulatory roles in plant metabolism, which, in most cases, was involved in the regulation at the transcription levels of relevant genes.

In the cold acclimated (CA) state, a reduced tissue water content is considered important to survive subzero temperatures. However, the causal relationship between the reduced water content and increased frost hardiness is unclear. Our aim was to assess whether the seasonally reduced water content affects the freezing dynamics and the amount of ice formed in evergreen leaves: Xeromorph leaves of the woody species Buxus sempervirens and Hedera helix were compared with the herbaceous, soft-leaved Bellis perennis in the non-acclimated (NA) state in summer, during cold acclimation, and in the fully CA state in winter. Freezing dynamics were studied using differential scanning calorimetry in addition to the volume fraction of ice and related to water content, osmotic potential, and frost hardiness. In the CA state, freezing dynamics were slower than in NA state. In xeromorph leaves, displacement from ideal equilibrium freezing was higher than in B. perennis. Freeze dehydration was lower in CA state. In the CA state, water content and osmotic potential were reduced, except for B. sempervirens, where the water content remained unchanged. Active osmoregulation and controlled dehydration (only found in two species), are supporting cellular water retention against the dehydrative force of extracellular ice. B. perennis had the highest water content and the least negative osmotic potential and was the most frost susceptible species (LT₁₀: 8.4 °C CA). The leaves froze at ideal equilibrium. 83 % of the total water froze, occupying more than 60 vol%. H. helix (LT₁₀: 18.4 °C CA) was frost hardier and B. sempervirens (LT₁₀: 28.8 °C CA) the frost hardiest species, but in contrast to the other species tested got frost killed by intracellular freezing. The xeromorph leaves froze at non-ideal equilibrium and had lesser ice masses. Despite an increase in frost hardiness with CA, the volume fraction of ice at LT₁₀ was the same (30–40 vol%). In the CA state, slower freeze dehydration and at the same subzero temperature lesser ice masses appeared to be important for higher frost hardiness. Overall, an important component of cold acclimation in evergreen leaves was the slowing of freezing dynamics, which, depending on the species, involved a specific cell architecture, osmoregulation, and a reduction in water content.

Vapor pressure deficit (VPD) directly affects the driving force of plant water movement by altering the water potential gradient between the atmosphere and plants and indirectly influences the resistance to water movement by regulating plant structure. Concurrently, light intensity modulates both the driving force and resistance to water movement by regulating plant morphology and nonstructural carbohydrate synthesis. Despite significant advances in the understanding of the regulatory effects of VPD on water absorption and transport in tomatoes, the effect of light intensity regulation under varying VPDs on water transport and homeostasis remains to be clarified. Here, we investigated the effects of two light intensities (L300; 300 µmol m^–2 s^–1, L600; 600 µmol m^–2 s^–1) on plant anatomy, physiological traits, hydraulic properties, and expression of plasma membrane intrinsic proteins (PIPs) and tonoplast intrinsic proteins (TIPs) in tomatoes subjected to long-term high and low VPDs. In addition, we analysed the correlations and path coefficients of these indicators. These results indicate that higher light intensity reduces resistance to water movement by enhancing root morphology, vessel parameters in roots and stems, leaf vein density, stomatal morphology, physiological traits, and expression of SlTIPs and SlPIPs in both roots and leaves. Concurrently, increased light intensity boosts the driving force of water movement by amplifying the water potential difference and transpiration under low VPD. However, under high VPD, elevated light intensities create a larger water potential difference, prompting plants to reduce this excessive force by decreasing transpiration and stomatal conductance, thereby maintaining water homeostasis. These findings suggest that light intensity can effectively regulate water homeostasis by dynamically optimising plant structure, hydraulic properties, and the expression of SlTIPs and SlPIPs across different VPDs, providing a theoretical foundation for practical light intensity management in agriculture.