Search Results (40)

Dehydration response element binding proteins (DREBs) have been identified as major regulators of cold acclimatization in many angiosperms. Cold stress is one of the primary abiotic stresses affecting kiwifruit growth and development. However, kiwifruit is currently one of the most widely consumed fruits worldwide because of its high nutritional value. 5-Aminolevulinic acid (5-ALA) is a nonprotein amino acid known for its distinct promotional effects on plant resistance, growth, and development. However, studies on the function of the kiwifruit DREB gene in alleviating low-temperature stress in its seedlings via exogenous 5-ALA have not been reported. Therefore, in this study, we performed a genome-wide identification of DREB gene family members in kiwifruit and analyzed the regulatory effects of exogenous 5-ALA on kiwifruit DREB genes under low-temperature stress. A total of 193 DREB genes were identified on 29 chromosomes. Phylogenetic analysis classified these genes into six subfamilies. Although there were some differences in cis-elements among subfamilies, all of them contained more biotic or abiotic stresses and hormone-related cis-acting elements. GO and KEGG enrichment analyses revealed that AcDREB plays an essential role in hormone signaling, metabolic processes, and the response to adverse stress. Under low-temperature stress, the application of exogenous 5-ALA inhibited the accumulation of APX and DHAR, promoted an increase in chlorophyll, and increased the accumulation of enzymes and substances such as 5-ALA, MDHAR, GR, ASA, GAH, and GSSH, thereby accelerating ROS scavenging and increasing the cold hardiness of kiwifruits. Functional analysis revealed that 46 differentially expressed DREB genes, especially those encoding AcDREB69, AcDREB92, and AcDREB148, which are involved in ethylene signaling and defense signaling, and, after the transcription of downstream target genes is activated, are involved in the regulation of low-temperature-stressed kiwifruits by exogenous 5-ALA, thus improving the cold tolerance of kiwifruits. Notably, AcDREB69, AcDREB92, and AcDREB148 could serve as key genes for cold tolerance. This study is the first to investigate the function of AcDREB genes involved in the role of exogenous 5-ALA in regulating low-temperature stress, revealing the regulatory mechanism by which DREB is involved in the ability of exogenous 5-ALA to alleviate low-temperature stress. Full article

Root-knot nematodes (RKNs), specifically Meloidogyne incognita, are notoriously difficult to eliminate as endophytic nematodes, and cause severe damage to various plants. Cucumber (Cucumis sativus), which is a cash crop widely grown across the world, is often infected by RKNs. ELONGATED HYPOCOTYL5 (HY5), a member of the bZIP transcription factor family, plays a vital role in hormone, nutrient, abiotic stress, biotic stress, and oxygen species (ROS) signaling pathways. However, the involvement of HY5 in the defense against RKNs has rarely been reported. The present study initially explored the response of CsHY5 to RKNs. The results indicated that the hy5 mutant had a higher number of nematodes and galls in the root system and exhibited a higher susceptibility to RKNs compared with the wild type (WT). Particularly, the root-knot nematodes in hy5 plants completed their life cycle more quickly and produced more eggs. The activities of defense-related hormones and antioxidant enzymes were measured, and the results indicated that JA, jasmonoyl-isoleucine (JA-Ile), abscisic acid (ABA), peroxidase (POD), and ascorbate peroxidase (APX) were significantly elevated in the wild type, but were not induced or decreased in the mutant. Through transcriptome sequencing analysis and quantitative real-time PCR (qRT-PCR), it was found that when RKNs infect plants, the key genes of jasmonic acid (JA) synthesis, CsAOC and CsAOS, as well as the key gene of the antioxidant system, CsPOD, were all significantly induced. Nevertheless, this induction effect disappeared in the hy5 mutant. Generally, CsHY5 plays a role in the response of cucumber to RKNs, and its deletion increases the sensitivity of cucumber to RKNs. These results suggest that CsHY5 may affect the resistance of cucumber to RKNs by affecting antioxidant enzyme activities and hormone content. Full article

Soil salinity significantly restricts the growth, development, and productivity of vegetables. Cucumber, a crucial greenhouse vegetable, is helpful for understanding how plants perceive, signal, and respond to salt stress. The WRKY family plays an important role in regulating stress responses. This study utilized the cucumber variety ‘Zhongnong 26’ to investigate the effects of salt stress on morphological changes, physiological and biochemical indices, and molecular regulations. CsWRKY46 was up-regulated in both salt stress and ABA response conditions in the leaves, roots, and fruits of cucumber. Transgenic Arabidopsis lines overexpressing CsWRKY46 (CsWRK46-OE1 and CsWRK46-OE5) showed higher proline accumulation and reduced electrolyte leakage compared to the wild type (WT). These overexpression lines demonstrated higher peroxidase (POD) and glutathione reductase (GR) activity, along with lower ascorbate peroxidase (APX) and catalase (CAT) activity. qRT-PCR analysis revealed elevated expression levels of ABI5 and ABF4 in CsWRKY46-OE lines compared to the WT. Additionally, the overexpression of CsWRKY46 increased the expression of stress-inducible genes such as PSCS1, PY19, and RD19. These findings suggest that CsWRKY46 enhances plant tolerance to salt stress, potentially through ABA regulation and modulation of cellular reactive oxygen species (ROS), and provide a foundation for the identification of new sources of salt stress tolerance for breeding programs. Full article

Salt stress is a major abiotic stress that interferes with plant growth and affects crop production. Dehydrin (DHN), a member of the late embryogenesis abundant (LEA) protein family, was considered to be a stress protein involved in the protective reaction of plant dehydration. Our previous research has shown that overexpression of the Suaeda salsa SsDHN gene enhances tolerance to salt stress in tobacco. However, the research on its protection in photosynthesis under salt stress remains unclear. In this study, gene overexpression (SsDHN-OE) tobacco plants were utilized to study the effect of the SsDHN gene on plant photosynthesis under salt stress. Our findings showed that overexpression of SsDHN increased the biomass, leaf area, root length, and root surface area in tobacco seedlings under salt stress conditions. The transgenic tobacco with overexpression of SsDHN had obvious stomatal closure, which effectively alleviated the adverse effects of salt stress on photosynthetic efficiency. Overexpression of the SsDHN gene in tobacco can effectively reduce the degree of photoinhibition and chloroplast damage caused by salt stress. Moreover, the SsDHN-overexpressing transgenic tobacco plants exhibited a decrease in oxidative damage and protected membrane structures related to photosynthesis by increasing antioxidant enzyme activity and antioxidant substance content. It was further found that the expression levels of photosynthetic and antioxidant-related genes Rubisco, SBPase, POD7, CAT3, APX2, and SOD3 were significantly up-regulated by overexpressing the SsDHN gene in tobacco seedlings under salt stress. In conclusion, the SsDHN gene might improve the salt stress resistance of tobacco seedlings and be involved in regulating photosynthesis and antioxidant activity under salt stress. Full article

Salt stress affects the growth, metabolism, yield, and quality of crops. To adapt to high-salt environments, plants form various regulatory mechanisms. Salt over sensitive (SOS) is the key gene of SOS signal transduction pathway. As a member of the SOS3 subfamily, the function of SOS3-3 under salt stress has not been reported. To verify the function of SOS3-3 and the morphological and physiological parameters, the expression of genes related to stress were compared between the SOS3-3 overexpressed (OESOS3-3) and silenced tomato (VSOS3-3) at control and 10 days’ NaCl treatment. The results showed that, compared with the control (Ve), the plants of VSOS3-3 were shorter under salt stress, with curled leaves and abscission. The fresh and dry weights, F_v/F_m, total chlorophyll content, antioxidant enzyme activities, and proline content of VSOS3-3 significantly decreased, while the relative conductivity, hydrogen peroxide (H₂O₂), and Malondialdehyde (MDA) content of VSOS3-3 plants significantly increased compared to that of WT, respectively. Compared to the wild-type (WT), OESOS3-3 plants were less damaged by salt stress, with significantly higher plant height, fresh and dry weights, F_v/F_m, total chlorophyll content, antioxidant enzyme activity, and proline content. However, the relative conductance, H₂O₂, and MDA content were significantly lower in OESOS3-3 than WT. The expression levels of SOS1, SOS2, LKT1 (ion transport-related gene), APX1 (ROS signaling pathway-related gene), P5CS (osmoregulation-related gene), and ABF4 (ABA signaling pathway-related gene) were significantly lower in VSOS3-3 than Ve, but significantly higher in OESOS3-3 than in WT. These results suggested that SOS3-3 regulate salt tolerance by influencing physiological and biochemical changes and the expression of genes related to stress response. This study revealed the mechanism of SOS family participating in regulating tomato salt tolerance, providing a theoretical basis for improving tomato salt tolerance. Full article

Ascorbate peroxidase (APX) is a crucial enzyme involved in cellular antioxidant defense and plays a pivotal role in modulating reactive oxygen species (ROS) levels under various environmental stresses in plants. This study utilized bioinformatics methods to identify and analyze the APX gene family of pomelo, while quantitative real-time PCR (qRT-PCR) was employed to validate and analyze the expression of CmAPXs at different stages of fruit postharvest. This study identified 96 members of the CmAPX family in the entire pomelo genome, with uneven distribution across nine chromosomes and occurrences of gene fragment replication. The subcellular localization includes peroxisome, cytoplasm, chloroplasts, and mitochondria. The CmAPX family exhibits a similar gene structure, predominantly consisting of two exons. An analysis of the upstream promoter regions revealed a significant presence of cis-acting elements associated with light (Box 4, G-Box), hormones (ABRE, TCA-element), and stress-related (MBS, LTR, ARE) responses. Phylogenetic and collinearity analyses revealed that the CmAPX gene family can be classified into three subclasses, with seven collinear gene pairs. Furthermore, CmAPXs are closely related to citrus, pomelo, and lemon, followed by Arabidopsis, and exhibit low homology with rice. Additionally, the transcriptomic heat map and qPCR results revealed that the expression levels of CmAPX57, CmAPX34, CmAPX50, CmAPX4, CmAPX5, and CmAPX81 were positively correlated with granulation degree, indicating the activation of the endogenous stress resistance system in pomelo cells by these genes, thereby conferring resistance to ROS. This finding is consistent with the results of GO enrichment analysis. Furthermore, 38 miRNAs were identified as potential regulators targeting the CmAPX family for post-transcriptional regulation. Thus, this study has preliminarily characterized members of the APX gene family in pomelo and provided valuable insights for further research on their antioxidant function and molecular mechanism. Full article

MYB transcription factors (TFs) play vital roles in plant growth, development, and response to adversity. Although the MYB gene family has been studied in many plant species, there is still little known about the function of R2R3 MYB TFs in sweet potato in response to abiotic stresses. In this study, an R2R3 MYB gene, IbMYB330 was isolated from sweet potato (Ipomoea batatas). IbMYB330 was ectopically expressed in tobacco and the functional characterization was performed by overexpression in transgenic plants. The IbMYB330 protein has a 268 amino acid sequence and contains two highly conserved MYB domains. The molecular weight and isoelectric point of IbMYB330 are 29.24 kD and 9.12, respectively. The expression of IbMYB330 in sweet potato is tissue-specific, and levels in the root were significantly higher than that in the leaf and stem. It showed that the expression of IbMYB330 was strongly induced by PEG-6000, NaCl, and H₂O₂. Ectopic expression of IbMYB330 led to increased transcript levels of stress-related genes such as SOD, POD, APX, and P5CS. Moreover, compared to the wild-type (WT), transgenic tobacco overexpression of IbMYB330 enhanced the tolerance to drought and salt stress treatment as CAT activity, POD activity, proline content, and protein content in transgenic tobacco had increased, while MDA content had decreased. Taken together, our study demonstrated that IbMYB330 plays a role in enhancing the resistance of sweet potato to stresses. These findings lay the groundwork for future research on the R2R3-MYB genes of sweet potato and indicates that IbMYB330 may be a candidate gene for improving abiotic stress tolerance in crops. Full article

Heat shock factors (Hsfs) play a crucial role in plant defense processes. However, the distribution and functional characteristics of Hsf genes in the relict plant Liriodendron chinense are still unclear. In this study, a total of 19 LcHsfs were identified and divided into three separate subgroups, comprising 10 LcHsfA, 7 LcHsfB, and 2 LcHsfC genes, respectively, based on their phylogenetic tree and the presence/absence of conserved protein domains. Whole-genome duplication and segmental duplication led to an expansion of the LhHsf gene family. The promoters of LcHsf genes are enriched for different types of cis-acting elements, including hormone responsive and abiotic-stress-responsive elements. The expression of LcHsfA3, LcHsfA4b, LcHsfA5, LcHsfB1b, and LcHsfB2b increased significantly as a result of both cold and drought treatments. LcHsfA2a, LcHsfA2b, and LcHsfA7 act as important genes whose expression levels correlate strongly with the expression of the LcHsp70, LcHsp110, and LcAPX genes under heat stress. In addition, we found that transiently transformed 35S:LcHsfA2a seedlings showed significantly lower levels of hydrogen peroxide (H₂O₂) after heat stress and showed a stronger thermotolerance. This study sheds light on the possible functions of LcHsf genes under abiotic stress and identifies potentially useful genes to target for molecular breeding, in order to develop more stress-resistant varieties. Full article

This study explores the impact of RNAi in terms of selectively inhibiting the expression of the OsBBTI5 gene, with the primary objective of uncovering its involvement in the molecular mechanisms associated with salt tolerance in rice. OsBBTI5, belonging to the Bowman–Birk inhibitor (BBI) family gene, is known for its involvement in plant stress responses. The gene was successfully cloned from rice, exhibiting transcriptional self-activation in yeast. A yeast two-hybrid assay confirmed its specific binding to OsAPX2 (an ascorbate peroxidase gene). Transgenic OsBBTI5-RNAi plants displayed insensitivity to varying concentrations of 24-epibrassinolide in the brassinosteroid sensitivity assay. However, they showed reduced root and plant height at high concentrations (10 and 100 µM) of GA₃ immersion. Enzyme activity assays revealed increased peroxidase (POD) and superoxide dismutase (SOD) activities and decreased malondialdehyde (MDA) content under 40-60 mM NaCl. Transcriptomic analysis indicated a significant upregulation of photosynthesis-related genes in transgenic plants under salt stress compared to the wild type. Notably, this study provides novel insights, suggesting that the BBI gene is part of the BR signaling pathway, and that OsBBTI5 potentially enhances stress tolerance in transgenic plants through interaction with the salt stress-related gene OsAPX2. Full article

The antioxidative enzyme ascorbate peroxidase (APX) exerts a critically important function through scavenging reactive oxygen species (ROS), alleviating oxidative damage in plants, and enhancing their tolerance to salinity. Here, we identified 28 CmAPX genes that display an uneven distribution pattern throughout the 12 chromosomes of the melon genome by carrying out a bioinformatics analysis. Phylogenetic analyses revealed that the CmAPX gene family comprised seven different clades, with each clade of genes exhibiting comparable motifs and structures. We cloned 28 CmAPX genes to infer their encoded protein sequences; we then compared these sequences with proteins encoded by rice APX proteins (OsAPX2), Puccinellia tenuiflora APX proteins (PutAPX) and with pea APX proteins. We found that the CmAPX17, CmAPX24, and CmAPX27 genes in Clade I were closely related, and their structures were highly conserved. CmAPX27 (MELO3C020719.2.1) was found to promote resistance to 150 mM NaCl salt stress, according to quantitative real-time fluorescence PCR. Transcriptome data revealed that CmAPX27 was differentially expressed among tissues, and the observed differences in expression were significant. Virus-induced gene silencing of CmAPX27 significantly decreased salinity tolerance, and CmAPX27 exhibited differential expression in the leaf, stem, and root tissues of melon plants. This finding demonstrates that CmAPX27 exerts a key function in melon’s tolerance to salt stress. Generally, CmAPX27 could be a target in molecular breeding efforts aimed at improving the salt tolerance of melon; further studies of CmAPX27 could unveil novel physiological mechanisms through which antioxidant enzymes mitigate the deleterious effects of ROS stress. Full article

Drought poses a significant challenge to global wheat production, and the application of exogenous phytohormones offers a convenient approach to enhancing drought tolerance of wheat. However, little is known about the molecular mechanism by which strigolactones (SLs), newly discovered phytohormones, alleviate drought stress in wheat. Therefore, this study is aimed at elucidating the physiological and molecular mechanisms operating in wheat and gaining insights into the specific role of SLs in ameliorating responses to the stress. The results showed that SLs application upregulated the expression of genes associated with the antioxidant defense system (Fe/Mn-SOD, PER1, PER22, SPC4, CAT2, APX1, APX7, GSTU6, GST4, GOR, GRXC1, and GRXC15), chlorophyll biogenesis (CHLH, and CPX), light-harvesting chlorophyll A-B binding proteins (WHAB1.6, and LHC Ib-21), electron transfer (PNSL2), E3 ubiquitin-protein ligase (BB, CHIP, and RHY1A), heat stress transcription factor (HSFA1, HSFA4D, and HSFC2B), heat shock proteins (HSP23.2, HSP16.9A, HSP17.9A, HSP21, HSP70, HSP70-16, HSP70-17, HSP70-8, HSP90-5, and HSP90-6), DnaJ family members (ATJ1, ATJ3, and DJA6), as well as other chaperones (BAG1, CIP73, CIPB1, and CPN60I). but the expression level of genes involved in chlorophyll degradation (SGR, NOL, PPH, PAO, TIC55, and PTC52) as well as photorespiration (AGT2) was found to be downregulated by SLs priming. As a result, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced, and chlorophyll content and photosynthetic rate were increased, which indicated the alleviation of drought stress in wheat. These findings demonstrated that SLs alleviate drought stress by promoting photosynthesis through enhancing chlorophyll levels, and by facilitating ROS scavenging through modulation of the antioxidant system. The study advances understandings of the molecular mechanism underlying SLs-mediated drought alleviation and provides valuable insights for implementing sustainable farming practice under water restriction. Full article

The antioxidant enzyme system is the main defense system responsible for maintaining cellular reactive oxygen species (ROS) homeostasis and normal plant growth and development after saline stress. In this study, we identified and characterized the members of the SOD, APX and CAT gene families of the antioxidant enzyme system in Gymnocarpos przewalskii, using plant physiology and molecular biology methods, and analyzed the pattern of enzyme activity in response to NaCl stress. It was found that seven, six and two genes of SOD, APX and CAT gene families, respectively, were expressed in the leaf tissue of G. przewalskii, in which most of the genes were significantly upregulated under NaCl stress, and the enzymatic activities were in accordance with the gene expression. Three positive selection sites in the GpCAT1 gene can increase the hydrophilicity of the GpCAT1 protein, increase the volume of the active site and increase the affinity for H₂O₂, thus improving the catalytic efficiency of GpCAT1. The results of the present study provide new insights for further investigations of the evolution and function of the SOD, APX and CAT gene families in G. przewalskii and their essential roles under salt stress, and the findings will be useful for revealing the molecular mechanism of salt tolerance and breeding of salt-tolerant plants. Full article

The TGACG motif-binding factor1 (TGA1) transcription factor, in which belongs to the bZIP transcription factor family and has vast application potential in plant growth and development. Here, we cloned the gene of the MtTGA1 transcription factor from Medicago truncatula. The MtTGA1 promoter region contains a diverse range of photoregulatory and hormonal regulatory elements. The expression profile of MtTGA1 indicated its highest expression in the root. Additionally, the expression level of MtTGA1 was significantly upregulated after SA and BR treatments and showed a downward trend after GA and ABA treatments. To explore the potential function of MtTGA1, we treated the transgenic plants with salt treatment for 15 days, and the results showed that transgenic plants demonstrated significantly longer root lengths and heightened activities of antioxidant enzymes such as ascorbic acid catalase (APX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) in their roots and leaves. The levels of endogenous hormones, including ABA and BR were improved in transgenic plants, with a marked change in the morphology of their leaf cells. Transcriptome analysis identified a total of 193 differentially expressed genes, which were significantly enriched in the pathways of “Brassinosteroid biosynthesis”, “Ascorbate and aldarate metabolism”, and “Plant hormone signal transduction”. Furthermore, MtTGA1 was found to interact with the SPX domain-containing protein 1 (SPX1) in Medicago truncatula. In conclusion, these results are beneficial for further studies about the plant growth and development regulatory network mediated by the TGA1 transcription factor family. Full article

Reversible phosphorylation of proteins is a ubiquitous regulatory mechanism in vivo that can respond to external changes, and plays an extremely important role in cell signal transduction. Protein phosphatase 2C is the largest protein phosphatase family in higher plants. Recently, it has been found that some clade A members can negatively regulate ABA signaling pathways. However, the functions of several subgroups of Arabidopsis PP2C other than clade A have not been reported, and whether other members of the PP2C family also participate in the regulation of ABA signaling pathways remains to be studied. In this study, based on the previous screening and identification work of PP2C involved in the ABA pathway, the clade F member PIA1 encoding a gene of the PP2C family, which was down-regulated after ABA treatment during the screening, was selected as the target. Overexpression of PIA1 significantly down-regulated the expression of ABA marker gene RD29A in Arabidopsis protoplasts, and ABA-responsive elements have been found in the cis-regulatory elements of PIA1 by promoter analysis. When compared to Col-0, transgenic plants overexpressing PIA1 were less sensitive to ABA, whereas pia1 showed the opposite trait in seed germination, root growth, and stomatal opening experiments. Under drought stress, SOD, POD, CAT, and APX activities of PIA1 overexpression lines were lower than Col-0 and pia1, while the content of H₂O₂ was higher, leading to its lowest survival rate in test plants, which were consistent with the significant inhibition of the expression of ABA-dependent stress-responsive genes RD29B, ABI5, ABF3, and ABF4 in the PIA1 transgenic background after ABA treatment. Using yeast two-hybrid and luciferase complementation assays, PIA1 was found to interact with multiple ABA key signaling elements, including 2 RCARs and 6 SnRK2s. Our results indicate that PIA1 may reduce plant drought tolerance by functioning as a common negative regulator involved in ABA signaling pathway. Full article