SlMYB102 expression enhances low-temperature stress resistance in tomato plants.
ABSTRACT: Herein, we identified the tomato SlMYB102 gene as a MYB family transcription factor of the R2R3-MYB subfamily. We additionally determined that the SlMYB102 promoter region contains photoresponsive, abiotic stress-responsive, and hormone-responsive regulatory elements, and we detected higher SlMYB102 expression in the reproductive organs of tomato than that in vegetative organs, with the expression being highest in ripe fruits and in roots. SlMYB102 expression was also shown to be cold-inducible. The protein encoded by SlMYB102 localized to the nucleus wherein it was found to mediate the transcriptional activation of target genes through its C-terminal domain. Overexpression of SlMYB102 in tomato plants conferred enhanced tolerance to cold stress. Under such cold stress conditions, we found that proline levels in the leaves of SlMYB102 overexpressing transgenic plants were higher than those in WT plants. In addition, S1MYB102 overexpression was associated with the enhanced expression of cold response genes including SlCBF1, SlCBF3, SlDREB1, SlDEB2, and SlICE1. We also found that the overexpression of SlMYB102 further enhanced the cold-induced upregulation of SlP5CS and SlAPX2. Taken together, these results suggest that SlMYB102 may be involved in the C-repeat binding transcription factor (CBF) and proline synthesis pathways, thereby improving tomato plant cold resistance.
Project description:MYB-type transcription factors play a diverse role in plant development and response to abiotic stress. This study isolated a rice R2R3-type MYB gene, OsMYB2, and functionally characterized its role in tolerance to abiotic stress by generating transgenic rice plants with overexpressing and RNA interference OsMYB2. Expression of OsMYB2 was up-regulated by salt, cold, and dehydration stress. OsMYB2 was localized in the nucleus with transactivation activity. No difference in growth and development between the OsMYB2-overexpressing and wild-type plants was observed under normal growth conditions, but the OsMYB2-overexpressing plants were more tolerant to salt, cold, and dehydration stresses and more sensitive to abscisic acid than wild-type plants. The OsMYB2-overexpressing plants accumulated greater amounts of soluble sugars and proline than wild-type plants under salt stress. Overexpression of OsMYB2 enhanced up-regulation of genes encoding proline synthase and transporters. The OsMYB2-overexpressing plants accumulated less amounts of H(2)O(2) and malondialdehyde. The enhanced activities of antioxidant enzymes, including peroxidase, superoxide dismutase, and catalase, may underlie the lower H(2)O(2) contents in OsMYB2-overexpressing plants. There was greater up-regulation of stress-related genes, including OsLEA3, OsRab16A, and OsDREB2A, in the OsMYB2-overexpressing plants. Microarray analysis showed that expression of numerous genes involving diverse functions in stress response was altered in the OsMYB2-overexpressing plants. These findings suggest that OsMYB2 encodes a stress-responsive MYB transcription factor that plays a regulatory role in tolerance of rice to salt, cold, and dehydration stress.
Project description:Our containment trials have established cold tolerance in Nicotiana tabacum osmotin (Nt Osm) transgenic tomato (Solanum lycopersicum L. cv. Pusa Ruby). Though, the stress tolerance mechanisms have been studied at physio-biochemical levels, molecular mechanisms underlying the tolerant response are still not well studied. Therefore, quantitative transcript expression of Osmotin and other stress responsive genes (CBF1, P5CS and APX) was studied in response to cold (4°C; 2 and 24 h) treatment in the transgenic and wild type tomato plants. The expression analysis revealed differential transcript regulation in the transgenic and wild type plants on the cold exposure. In general, the genes were either earlier induced or the extent of fold change in transcript expression over the respective untreated controls was higher in transgenic than in the wild type plants on cold exposure. The transcript expression data also supported the metabolite analysis on free Proline and ascorbate content. The results thus suggest that constitutive over expression of the Osmotin modulate transcript abundance and functional expression products of the other stress responsive genes thereby, imparting cold tolerance in the transgenic tomato plants.
Project description:MYB-type transcription factors (TFs) play essential roles in plant growth, development and respond to environmental stresses. Role of MYB-related TFs of rice in drought stress tolerance is not well documented. Here, we report the isolation and characterization of a novel MYB-related TF, OsMYB48-1, of rice. Expression of OsMYB48-1 was strongly induced by polyethylene glycol (PEG), abscisic acid (ABA), H2O2, and dehydration, while being slightly induced by high salinity and cold treatment. The OsMYB48-1 protein was localized in the nucleus with transactivation activity at the C terminus. Overexpression of OsMYB48-1 in rice significantly improved tolerance to simulated drought and salinity stresses caused by mannitol, PEG, and NaCl, respectively, and drought stress was caused by drying the soil. In contrast to wild type plants, the overexpression lines exhibited reduced rate of water loss, lower malondialdehyde (MDA) content and higher proline content under stress conditions. Moreover, overexpression plants were hypersensitive to ABA at both germination and post-germination stages and accumulated more endogenous ABA under drought stress conditions. Further studies demonstrated that overexpression of OsMYB48-1 could regulate the expression of some ABA biosynthesis genes (OsNCED4, OsNCED5), early signaling genes (OsPP2C68, OSRK1) and late responsive genes (RAB21, OsLEA3, RAB16C and RAB16D) under drought stress conditions. Collectively, these results suggested that OsMYB48-1 functions as a novel MYB-related TF which plays a positive role in drought and salinity tolerance by regulating stress-induced ABA synthesis.
Project description:Low temperature is a major stress that severely affects plant development, growth, distribution, and productivity. Here, we examined the function of a 2-oxoglutarate-dependent dioxygenase-encoding gene, SlF3HL, in chilling stress responses in tomato (Solanum lycopersicum cv. Alisa Craig [AC]). Knockdown (KD) of SlF3HL (through RNA interference) in tomato led to increased sensitivity to chilling stress as indicated by elevated levels of electrolyte leakage, malondialdehyde (MDA) and reactive oxygen species (ROS). In addition, the KD plants had decreased levels of proline and decreased activities of peroxisome and superoxide dismutase. The expression of four cold-responsive genes was substantially reduced in the KD plants. Furthermore, seedling growth was significantly greater in AC or SlF3HL-overexpression plants than in the KD plants under either normal growth conditions with methyl jasmonate (MeJA) or chilling stress conditions. SlF3HL appears to positively regulate JA accumulation and the expression of JA biosynthetic and signaling genes under chilling stress. Together, these results suggest that SlF3HL is a positive regulator of chilling stress tolerance and functions in the chilling stress tolerance pathways, possibly by regulating JA biosynthesis, JA signaling, and ROS levels.
Project description:Dehydrins are late embryogenesis abundant proteins that help regulate abiotic stress responses in plants. Overexpression of the Saussurea involucrata dehydrin gene SiDHN has previously been shown to improve water-use efficiency and enhance cold and drought tolerance of transgenic tobacco. To understand the mechanism by which SiDHN exerts its protective function, we transformed the SiDHN gene into tomato plants (Solanum lycopersicum L.) and assessed their response to abiotic stress. We observed that in response to stresses, the SiDHN transgenic tomato plants had increased contents of chlorophyll a and b, carotenoid and relative water content compared with wild-type plants. They also had higher maximal photochemical efficiency of photosystem II and accumulated more proline and soluble sugar. Compared to those wild-type plants, malondialdehyde content and relative electron leakage in transgenic plants were not significantly increased, and H2O2 and O2- contents in transgenic tomato plants were significantly decreased. We further observed that the production of stress-related antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, peroxidase, and catalase, as well as pyrroline-5-carboxylate synthetase and lipid transfer protein 1, were up-regulated in the transgenic plants under cold and drought stress. Based on these observations, we conclude that overexpression of SiDHN gene can promote cold and drought tolerance of transgenic tomato plants by inhibiting cell membrane damage, protecting chloroplasts, and enhancing the reactive oxygen species scavenging capacity. The finding can be beneficial for the application of SiDHN gene in improving crop tolerance to abiotic stress and oxidative damage.
Project description:BACKGROUND:Tomatoes (Lycopersicon esculentum Mill) are key foods, and their molecular biology and evolution have been well described. Tomato plants originated in the tropics and, thus, are cold sensitive. RESULTS:Here, we generated LeGPA1 overexpressing and RNA-interference (RNAi) transgenic tomato plants, which we then used to investigate the function of LeGPA1 in response to cold stress. Functional LeGPA1 was detected at the plasma membrane, and endogenous LeGPA1 was highly expressed in the roots and leaves. Cold treatment positively induced the expression of LeGPA1. Overexpression of LeGPA1 conferred tolerance to cold conditions and regulated the expression of genes related to the INDUCER OF CBF EXPRESSION-C-REPEAT-BINDING FACTOR (ICE-CBF) pathway in tomato plants. In the LeGPA1-overexpressing transgenic plants, the superoxide dismutase, peroxidase, and catalase activities and soluble sugar and proline contents were increased, and the production of reactive oxygen species and membrane lipid peroxidation decreased under cold stress. CONCLUSIONS:Our findings suggest that improvements in antioxidant systems can help plants cope with the oxidative damage caused by cold stress, thereby stabilizing cell membrane structures and increasing the rate of photosynthesis. The data presented here provide evidence for the key role of LeGPA1 in mediating cold signal transduction in plant cells. These findings extend our knowledge of the roles of G-proteins in plants and help to clarify the mechanisms through which growth and development are regulated in processing tomato plants.
Project description:Cold stress is considered as one of the major environmental factors that adversely affects the plant growth and distribution. Therefore, there arises an immediate need to cultivate effective strategies aimed at developing stress-tolerant crops that would boost the production and minimise the risks associated with cold stress. In this study, a novel cold-responsive protein1 (BoCRP1) isolated from Brassica oleracea was ectopically expressed in a cold susceptible tomato genotype Shalimar 1 and its function was investigated in response to chilling stress. BoCRP1 was constitutively expressed in all the tissues of B. oleracea including leaf, root and stem. However, its expression was found to be significantly increased in response to cold stress. Moreover, transgenic tomato plants expressing BoCRP1 exhibited increased tolerance to chilling stress (4 °C) with an overall improved rate of seed germination, increased root length, reduced membrane damage and increased accumulation of osmoprotectants. Furthermore, we observed increased transcript levels of stress responsive genes and enhanced accumulation of reactive oxygen species scavenging enzymes in transgenic plants on exposure to chilling stress. Taken together, these results strongly suggest that BoCRP1 is a promising candidate gene to improve the cold stress tolerance in tomato.
Project description:The MYB proteins comprise one of the largest families of transcription factors (TFs) in plants. Although several MYB genes have been characterized to play roles in secondary metabolism, the MYB family has not yet been identified in apple. In this study, 229 apple MYB genes were identified through a genome-wide analysis and divided into 45 subgroups. A computational analysis was conducted using the apple genomic database to yield a complete overview of the MYB family, including the intron-exon organizations, the sequence features of the MYB DNA-binding domains, the carboxy-terminal motifs, and the chromosomal locations. Subsequently, the expression of 18 MYB genes, including 12 were chosen from stress-related subgroups, while another 6 ones from other subgroups, in response to various abiotic stresses was examined. It was found that several of these MYB genes, particularly MdoMYB121, were induced by multiple stresses. The MdoMYB121 was then further functionally characterized. Its predicted protein was found to be localized in the nucleus. A transgenic analysis indicated that the overexpression of the MdoMYB121 gene remarkably enhanced the tolerance to high salinity, drought, and cold stresses in transgenic tomato and apple plants. Our results indicate that the MYB genes are highly conserved in plant species and that MdoMYB121 can be used as a target gene in genetic engineering approaches to improve the tolerance of plants to multiple abiotic stresses.
Project description:Drought stress can trigger the production of ABA in plants, in response to adverse conditions, which induces the transcript of stress-related marker genes. The R2R3 MYB TFs are implicated in regulation of various plants developmental, metabolic and multiple environmental stress responses. Here, a R2R3-MYB cloned gene, GaMYB62L, was transformed in Arabidopsis and was functionally characterized. The GaMYB62L protein contains two SANT domains with a conserved R2R3 imperfect repeats. The GaMYB62L cDNA is 1,017 bp with a CDS of 879, encodes a 292-residue polypeptide with MW of 38.78 kD and a pI value of 8.91. Overexpressed GaMYB62L transgenic Arabidopsis have increased proline and chlorophyll content, superior seed germination rate under salt and osmotic stress, less water loss rate with reduced stomatal apertures, high drought avoidance as compared to WT on water deprivation and also significant plant survival rates at low temperature. In addition, overexpressed GaMYB62L lines were more sensitive to ABA mediated germination and root elongation assay. Moreover, ABA induced GaMYB62L overexpression, enhanced the expression of ABA stress related marker genes like RD22, COR15A, ADH1, and RD29A. Together, overexpression of GaMYB62L suggested having developed better drought, salt and cold tolerance in transgenic Arabidopsis and thus presented it as a prospective candidate gene to achieve better abiotic stress tolerance in cotton crop.
Project description:Sl-ERF.B.3 (Solanum lycopersicum ethylene response factor B.3) gene encodes for a tomato transcription factor of the ERF (ethylene responsive factor) family. Our results of real-time RT-PCR showed that Sl-ERF.B.3 is an abiotic stress responsive gene, which is induced by cold, heat, and flooding, but downregulated by salinity and drought. To get more insight into the role of Sl-ERF.B.3 in plant response to separate salinity and cold, a comparative study between wild type and two Sl-ERF.B.3 antisense transgenic tomato lines was achieved. Compared with wild type, Sl-ERF.B.3 antisense transgenic plants exhibited a salt stress dependent growth inhibition. This inhibition was significantly enhanced in shoots but reduced in roots, leading to an increased root to shoot ratio. Furthermore, the cold stress essay clearly revealed that introducing antisense Sl-ERF.B.3 in transgenic tomato plants reduces their cell injury and enhances their tolerance against 14 d of cold stress. All these results suggest that Sl-ERF.B.3 gene is involved in plant response to abiotic stresses and may play a role in the layout of stress symptoms under cold stress and in growth regulation under salinity.