Plant Growth Regulation最新文献

Plant peptide hormones play crucial roles in plant development, defense against pathogens, and tolerance to abiotic stress. However, only a limited number of hormone-like peptides have been confirmed to contribute to salt and drought stress tolerance in plants beyond Arabidopsis. This study focuses on the isolation and characterization of MsPROPEP1, a propeptide precursor gene from the leguminous grass Medicago sativa. The transcription of MsPROPEP1 was shown to be inducible by NaCl, polyethylene glycol (PEG), and abscisic acid (ABA). Constitutive expression of MsPROPEP1 in alfalfa seedlings alleviated growth restrictions caused by salinity or osmotic stress and increased sensitivity to ABA-induced stomatal closure. Furthermore, application of synthesized MsPep1 peptide enhanced tolerance to stress induced by NaCl and PEG. In MsPROPEP1 overexpression transgenic plants, activation of several ABA-dependent stress-responsive genes was observed. These results highlight MsPROPEP1 as a potential candidate for genetic manipulation to enhance salinity and drought tolerance in legume species.

The global climate model predicts frequent and severe droughts in the future, resulting in limited crop production affecting growth and yield. The extent of drought tolerance in two wheat cultivars (WMRI-1 and BARI GOM-33) was investigated by foliar application of abscisic acid (ABA) and glycine betaine (GB) at the anthesis and grain filling stages. A pot experiment maintaining a completely randomized design with four replications was set in the field laboratory of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh. A total of four treatments were followed such as (i) Control (20–22% moisture content), (ii) Drought (8–10% moisture content), (iii) Drought + ABA, and (iv) Drought + GB. The plants at the reproductive stage were sprayed weekly with ABA (20 µM) and GB (50 mM) solutions under drought conditions. Drought stress significantly declined chlorophyll content and photosynthetic rate in comparison to control. However, the foliar application of ABA and GB under drought considerably increased the rate of photosynthesis and pigment contents in the flag leaves compared to the plants grown under individual drought conditions. A considerable increase in lipid peroxidation and H₂O₂ content in flag leaves was recorded in all drought conditions, while these values were reduced in ABA and GB treatments. ABA and GB application significantly enhanced the catalase and peroxidase enzyme activities and total antioxidant capacity, reducing oxidative damage and increasing grain yield. A hierarchical clustering heatmap using the stress tolerance index (STI) showed that Drought + ABA and Drought + GB secured higher STI scores, suggesting a greater drought tolerance in both cultivars compared to individual drought treatments. In conclusion, foliar spraying of ABA and GB enhanced drought tolerance in both wheat cultivars by altering physiology and antioxidative defense, suggesting a declined state of oxidative damage with increased yield.

Saintpaulia (Saintpaulia ionantha), a popular indoor ornamental potted plant, is native to the highlands of Kenya and Tanzania where temperatures rarely fall below 4 °C. Chilling injury during cultivation and transportation is a major commercial problem in Saintpaulia. In this study, we investigated chilling acclimation in Saintpaulia ‘Kilauea’. Plants grown at 20 °C (14 h light/10 h dark) displayed rapid and severe chilling injury after 24-h exposure to 4 °C. However, chilling injury at 4 °C could be dramatically reduced by pre-treating the plants at 10 °C but not at 6 °C. From whole genome analysis, 161 ethylene-responsive factors (ERFs) were identified and classified into 12 clades according to existing reports. Among these ERFs, 43, 8, and 4 ERFs were upregulated at 12, 24, and 48 h after 10 °C treatment, respectively. Most of these ERFs had GCC box and/or DRE/CRT core motifs-like sequences in their upstream regions. Finally, we compared the expression of ERFs between the treatments for 24 h at 10 °C, an effective temperature for chilling acclimation, and 6 °C, an ineffective temperature. The results showed that the expression of all six ERFs we investigated was increased by the 10 °C treatment, but not or only barely increased by the 6 °C treatment. This study suggests that Saintpaulia, a subtropical plant, can acclimate to low temperatures and that ERF upregulation is involved in chilling acclimation.

Walnut, an essential oilseed tree, is widely cultivated in regions such as Xinjiang, China. However, extensive saline-alkali land has significantly reduced the walnut field. Consequently, breeding salt-tolerant walnut rootstocks is crucial to development of industry. In this study, two walnut varieties (Cd and Xw) were subjected to NaCl salinity (0, 50, 100, 150 mM) to investigate physiological and molecular mechanisms of salt stress resistance. Our results revealed that salinity stress reduced growth parameters (shoot biomass, root biomass, relative ground and height growth) and photosynthetic pigments (Pn, Tr, and Cond) in both Cd and Xw compared to control plants. Additionally,as stress duration increased, proline content and antioxidant enzyme activity decreased. Transcriptomic analysis identified 9077 differentially expressed genes (DEGs), with Gene Ontology(GO) analyses indicating their involvement in hormone signaling, photosynthesis, light harvesting, and photosystems (I and II). WGCNA analysis identified hub genes highly associated with salt response, focusing on the light-harvesting chlorophyll protein complex (JrLHCb5, JrLHCa), MAPK signaling pathway (JrSAPK2), and hormone signaling processes (JrPYL4, JrSCL13). This study provides scientific evidence for further exploration of physiological and molecular mechanisms of salt tolerance in walnuts.

Buckwheat (Fagopyrum tataricum), a crop with both food and medicinal applications, holds significant economic value particularly in regions with arid or barren land. In order to explore the physiological and metabolic mechanism of drought stress resistance in different varieties of buckwheat, we conducted analyses on morphophysiological indicators and metabolomes of two distinct drought-tolerant buckwheat varieties exposed to drought treatments of different durations. The results revealed that drought stress exacerbated cell membrane damage, reduced chlorophyll content, and impaired antioxidant enzyme activity in both buckwheat varieties. However, the novel species DK19 exhibited greater resistance to drought compared to cultivated buckwheat K33. Metabolomics approaches were employed to examine metabolite changes in DK19 and K33 during two critical periods (day 7 and day 11) of drought stress. As a result, 15 significantly altered metabolites were identified in different materials within the network of amino acid biosynthesis pathways. Furthermore, 16 significantly enriched metabolites in the phenylpropanoid biosynthesis pathway as well as 17 significantly enriched metabolites in flavonoids biosynthesis pathway were detected. Additionally, based on metabolite changes, we determined differential expression levels of six genes related to amino acid metabolism networks and 12 key genes highly associated with secondary metabolism. Moreover, we observed distinct accumulation patterns of secondary metabolites phenylpropanoids (including hydroxycinnamates and flavonoids) in the two materials, which may contribute to the improved drought resistance of the novel tartary buckwheat cultivars. These findings provide valuable clues for the breeding of perennial buckwheat and solid foundations for genetically improving the drought resistance of buckwheat in the future.

The herbicide glyphosate inhibits the key enzyme 5-enolpyruvate shikimate-3-phosphate synthase (EPSPS) in the aromatic amino acid synthesis pathway of plants. This study aims to explore the Y-EPSPS gene derived from maize through codon optimization and validate its glyphosate resistance in Arabidopsis Thaliana. Germination rates of seeds under different glyphosate concentrations revealed that seeds overexpressing the Y-EPSPS gene exhibited higher germination rates compared to wild-type seeds. DAB and NBT staining methods were used to measure ROS levels in Arabidopsis plants under 0.8 mM glyphosate stress, showing that plants overexpressing Y-EPSPS had lower ROS levels compared to wild-type plants. Soluble sugar and malondialdehyde (MDA) content were higher in Y-EPSPS overexpressing plants, whereas MDA content was lower, indicating a potential stress response to glyphosate. Chlorophyll content and FV/FW ratio were higher in plants overexpressing Y-EPSPS compared to wild-type plants, suggesting reduced susceptibility to glyphosate. Enzyme activity and gene expression analysis further demonstrated significant increases in POD, SOD, and CAT enzyme activities in Y-EPSPS overexpressing plants compared to wild-type, while SD enzyme activity decreased significantly. Expression levels of ROS detoxification-related genes (AtCAT3 and AtSOD1) and stress defense-related genes (AtLTP3, AtSOS1, and DQSD) were also elevated to varying degrees in Y-EPSPS overexpressing plants compared to wild-type plants. These results indicate that the optimized Y-EPSPS gene confers certain resistance to glyphosate.

Three novel DREB (Dehydration-Responsive Element Binding protein) genes, designated as CiDREB2A, CiDREB5A and CiDREB6A, were individually isolated from chicory (Cichorium intybus L). Based on phylogenetic tree analysis, all three genes possessed a conserved AP2/EREBP domain and were subsequently categorized into the A2, A5, and A6 subgroups within the DREB subfamily, respectively. All of them contained a conserved AP2/EREBP domain and were classified into the A2, A5 and A6 subgroup of the DREB subfamily based on phylogenetic tree analysis, respectively. Quantitative real-time PCR analysis indicated that these genes were all induced by abiotic stresses. A subcellular localization assay revealed that these CiDREBs were localized in the nucleus. In addition, these three CiDREB proteins were also identified to bind the DRE motif of RD19A as shown by yeast one-hybrid experiments. Overexpression of CiDREB2A was found to promote sensitivity to high temperature at the post-germination stages in Arabidopsis while expression of heat shock proteins were decreased in the overexpressing plants compared to that of the control group under high temperature treatment. These results suggest that these CiDREBs may play an important role in regulation of stress-responsive signaling in chicory.

The pathogenic bacterium, Ralstonia solanacearum, causes bacterial wilt disease in many crops, which leads to significant yield losses worldwide. Although genes associated with resistance to this pathogen have been isolated and characterized in crops, the molecular mechanisms underlying the plant–pathogen interactions remain to be elucidated. Here, we performed a comparative transcriptional profiling analysis of tobacco (Nicotiana tabacum) cultivars C048 (susceptible) and C244 (resistant) in response to R. solanacearum infection. We found that the number of down- and up-regulated genes increased dramatically 3 h post inoculation (hpi), peaked 24 hpi, and then decreased 48 and 72 hpi, representing a “transcriptomic shock”. Of these genes, those associated with biotic and abiotic stresses and secondary metabolism were up-regulated, whereas those associated with primary metabolism were down-regulated. Alternative splicing (AS) modulates root defense against R. solanacearum by fine-tuning gene expression during the transcriptomic responses to pathogen invasion. The numbers of skipped exon (SE) and mutually exclusive exon (MXE) type AS events were reduced by approximately 60–80% in roots 9–72 hpi compared to those occurring 0–3 hpi. On the contrary, the number of differential alternative splicing (DAS) events showing a change in isoform ratio between samples increased, and most of them were associated with the down-regulation of corresponding gene expression. In addition, genes encoding transcription factors and leucine-rich repeat domain proteins that showed changes in both expression level and AS profile during pathogen infection were identified. Our study offers novel insights into the mechanisms underlying the transcriptional and post-transcriptional regulation of the tobacco response to R. solanacearum infection and will benefit the molecular breeding of pathogen-resistant tobacco in the future.

Copper (Cu) contamination in agricultural soils is one of the health risks, due to its translocation to humans through the food chain. Therefore, optimized nutrient application is required to achieve higher yields with reduced Cu uptake, ensuring food security. One way to reduce soil contamination is phytoremediation. Phosphorus (P) application decreases oxidative stress, improves plant growth, and facilitates the phytoremediation potential of plants. This study investigated the phytoremediation potential of kenaf (Hibiscus cannabinus) with P fertilizer in Cu-polluted mining soil (2375 mg kg^− 1 Cu) of Hubei, China. A pot experiment was conducted to assess the effect of P on kenaf growth, gas exchange traits, antioxidant enzyme activities, Cu uptake, and soil health under different levels of P (0, 10, 15, and 20 g/15 kg of soil). P₁₅ significantly improved plant growth by increasing plant height, stem diameter, number of leaves, and SPAD (relative chlorophyll index). Application of P improved net photosynthesis (Pn), transpiration rate (Tr), stomatal conductance (gs), and intercellular CO₂ concentration (Ci) while decreasing oxidative stress in kenaf leaves up to P₁₅. Contradictory, a high concentration of P₂₀ was toxic to the morphological and physiological traits of the plants. Maximum Cu uptake was observed at P₂₀ in roots, leaves, stems, and fibers. Additionally, P application significantly decreased soil pH and bulk density. Our findings revealed the effectiveness of P application in improving kenaf growth in heavily Cu-polluted mining soil.

Late embryogenesis abundant (LEA) protein plays an important role in plant response to abiotic stress and growth and development. Research has found that LEA protein plays an important role in plant response to drought stress. Although LEA can enhance plant drought resistance, its specific mechanism of action is not yet clear. To elucidate the potential mechanism of LEA protein in drought resistance, a drought-responsive gene designated ZmNHL2 was identified. Bioinformatics analysis showed that the protein encoded by ZmNHL2 belongs to the LEA-2 protein family. ZmNHL2 contains stress response cis-regulatory elements and ABRE response elements and has positive responses to drought, high temperature, salt stress, and exogenous ABA treatment. Transgenic Arabidopsis and maize plants constitutively overexpressing ZmNHL2 were generated for functional analysis of ZmNHL2. The Arabidopsis Col-0 and the maize B104 wild-type plants showed severe wilting and yellowing of the leaves in response to drought stress induction, whereas the ZmNHL2-overexpression lines showed upright leaves and less wilting and yellowing. Moreover, the relative water content (RWC), and the activities of superoxide dismutase (SOD) and peroxidase (POD) in the ZmNHL2-overexpression transgenic Arabidopsis and maize plants were higher than that of the WT plants, indicating that the overexpression of ZmNHL2 enhances maize tolerance to drought stress. RT-qPCR showed that ZmNHL2-overexpression transgenic plants exhibited higher expression levels of the drought-responsive genes ZmPOD1 and ZmDREB2A, and the ABA-related genes ZmNCED and ZmABF2 under drought-stressed conditions. Our results provide new insights into the regulatory functions and mechanisms of ZmNHL2 in promoting drought tolerance in maize.