MYB superfamily is one of the most abundant families in plants, which plays important roles in plant growth, development, and productivity. However, to date, researches on MYBs in wheat (Triticum ...aestivum L.) are scattered mostly, not comprehensive.
In this study, a total of 393 R2R3-MYBs and 12 R1R2R3-MYBs were identified and analyzed including gene structure, chromosomal distribution, synteny relationship, and evolutionary relationship. Then, 29 clusters tandem duplication and 8 clusters segmental duplication genes were discovered. The expression profile of the identified genes under abiotic and biotic stress was analyzed using RNA-seq data. Based on expression patterns analysis, we screened many candidate genes involved in plant response to abiotic and biotic stress. Among them, the functional characteristics of TaMYB344 were further studied. TaMYB344 was localized in the nucleus and functioned as a weak transcriptional activator. We demonstrated that TaMYB344-overexpressing transgenic tobacco plants had enhanced tolerance to drought, heat, and high salt stress.
In this study, 393 R2R3-MYBs and 12 R1R2R3-MYBs in wheat were systemically identified and analyzed. Differential expression analysis indicated that many R2R3-MYBs were involved in abiotic and biotic stress response. We identified a potential candidate gene TaMYB344, overexpression of which in tobacco plants enhanced drought, heat, and salt stress tolerance. These results will provide abundant molecular data for breeding new varieties of wheat in the future.
Cultivating new crop cultivars with multiple abiotic stress tolerances is important for crop production. The abscisic acid‐stress‐ripening (ASR) protein has been shown to confer abiotic stress ...tolerance in plants. However, the mechanisms of ASR function under stress condition remain largely unclear. In this study, we characterized all ASR family members in common wheat and constitutively overexpressed TaASR1‐D in a commercial hexaploid wheat cultivar Zhengmai 9023. The transgenic wheat plants exhibited increased tolerance to multiple abiotic stresses and increased grain yields under salt stress condition. Overexpression of TaASR1‐D conferred enhanced antioxidant capacity and ABA sensitivity in transgenic wheat plants. Further, RNA in situ hybridization results showed that TaASR1‐D had higher expression levels in the vascular tissues of leaves and the parenchyma cells around the vascular tissues of roots and stems. Yeast one‐hybrid and electrophoretic mobility shift assays revealed that TaASR1‐D could directly bind the specific cis‐elements in the promoters of TaNCED1 and TaGPx1‐D. In conclusion, our findings suggest that TaASR1‐D can be used to breed new wheat cultivars with increased multiple abiotic stress tolerances, and TaASR1‐D enhances abiotic stress tolerances by reinforcing antioxidant capacity and ABA signalling.
•Wheat MYB gene TaMyb1D was cloned.•The expression levels of TaMyb1D was induced under PEG and H2O2 treatments.•TaMyb1D regulated phenylpropanoid metabolism and affected plant development.•TaMyb1D ...enhanced drought and oxidative stress tolerance in transgenic tobacco plants.
MYB transcription factors are involved in the regulation of plant development and response to biotic and abiotic stress. In this study, TaMyb1D, a novel subgroup 4 gene of the R2R3-MYB subfamily, was cloned from wheat (Triticum aestivum L.). TaMyb1D was localized in the nucleus and functioned as a transcriptional repressor. The overexpression of TaMyb1D in tobacco (Nicotiana tabacum) plants repressed the expression of genes related to phenylpropanoid metabolism and down-regulated the accumulation of lignin in stems and flavonoids in leaves. These changes affected plant development under normal conditions. The expression of TaMyb1D was ubiquitous and up-regulated by PEG6000 and H2O2 treatments in wheat. TaMyb1D-overexpressing transgenic tobacco plants exhibited higher relative water content and lower water loss rate during drought stress, as well as higher chlorophyll content in leaves during oxidative stress. The transgenic plants showed a lower leakage of ions as well as reduced malondialdehyde and H2O2 levels during conditions of drought and oxidative stresses. In addition, TaMyb1D up-regulated the expression levels of ROS- and stress-related genes in response to drought stress. Therefore, the overexpression of TaMyb1D enhanced tolerance to drought and oxidative stresses in tobacco plants. Our study demonstrates that TaMyb1D functions as a negative regulator of phenylpropanoid metabolism and a positive regulator of plant tolerance to drought and oxidative stresses.
The 14-3-3 proteins are involved in plant growth, development, and in responding to abiotic stresses. However, the precise functions of 14-3-3s in responding to drought and salt stresses remained ...unclear, especially in wheat. In this study, a 14-3-3 gene from wheat, designated TaGF14b, was cloned and characterized. TaGF14b was upregulated by polyethylene glycol 6000, sodium chloride, hydrogen peroxide, and abscisic acid (ABA) treatments. Ectopic expression of TaGF14b in tobacco conferred enhanced tolerance to drought and salt stresses. Transgenic tobaccos had longer root, better growth status, and higher relative water content, survival rate, photosynthetic rate, and water use efficiency than control plants under drought and salt stresses. The contribution of TaGF14b to drought and salt tolerance relies on the regulations of ABA biosynthesis and ABA signaling, as well as stomatal closure and stress-related gene expressions. Moreover, TaGF14b expression could significantly enhance the reactive oxygen species (ROS) scavenging system to ameliorate oxidative damage to cells. In addition, TaGF14b increased tolerance to osmotic stress evoked by drought and salinity through modifying water conservation and compatible osmolytes in plants. In conclusion, TaGF14b enhances tolerance to multiple abiotic stresses through the ABA signaling pathway in transgenic tobaccos by altering physiological and biochemical processes.
MYB transcription factors play important roles in plant responses to biotic and abiotic stress. In this study,
, a R2R3-MYB gene, was cloned from wheat (
L.). TaODORANT1 was localized in the nucleus ...and functioned as a transcriptional activator.
was up-regulated in wheat under PEG6000, NaCl, ABA, and H
O
treatments.
-overexpressing transgenic tobacco plants exhibited higher relative water content and lower water loss rate under drought stress, as well as lower Na
accumulation in leaves under salt stress. The transgenic plants showed higher CAT activity but lower ion leakage, H
O
and malondialdehyde contents under drought and salt stresses. Besides, the transgenic plants also exhibited higher SOD activity under drought stress. Our results also revealed that
overexpression up-regulated the expression of several ROS- and stress-related genes in response to both drought and salt stresses, thus enhancing transgenic tobacco plants tolerance. Our studies demonstrate that TaODORANT1 positively regulates plant tolerance to drought and salt stresses.
Curcuma wenyujin is the source plant of three traditional Chinese medicines, which have been widely used in clinical treatment over 1000 years. The content of terpenes, the major medicinal active ...ingredients, is relatively low in this plant. Studies have shown that MeJA can promote terpenes biosynthesis in plants. However, the mechanism underlying the effect of MeJA in C. wenyujin remains unclear. In this work, the transcriptome of C. wenyujin leaves with MeJA treatment was analyzed to elucidate the regulation mechanism of MeJA-mediated terpene biosynthesis. Based on the RNA-seq data, 7,246 unigenes were differentially expressed with MeJA treatment. Expression pattern clustering of DEGs revealed that unigenes, related to JA biosynthesis and signal transduction, responded to exogenous MeJA stimulation on the early stage and maintained throughout the process. Subsequently, unigenes related to terpene biosynthesis pathway showed a significant up-regulation with 6 h treatment. The analysis results suggested that MeJA induced the expression of JA biosynthesis genes (such as LOXs, AOSs, AOCs, OPRs, and MFPs) and JA signal transduction core genes (JAZs and MYCs) to activate JA signaling pathway. Meanwhile, downstream JA-responsive genes presented up-regulated expression levels such as AACT, HMGSs, HMGRs, DXSs, DXRs, MCTs, HDSs, and HDRs, thus promoting terpenes biosynthesis. The transcriptional expressions of these genes were validated by qRT-PCR. In addition, six CwTPS genes in response to MeJA were identified. With MeJA treatment, the expression levels of CwTPSs were increased as well as those of the transcription factors MYB, NAC, bZIP, WRKY, AP2/ERF, and HLH. These TFs might potentially regulate terpenes biosynthesis. These results provide insights for regulation mechanism of terpenes biosynthesis.
One of the challenges in biocatalysis is the development of stable and efficient bi-enzymatic cascades for bio-redox reactions coupled to the recycling of soluble cofactors. Aldo-keto reductase (LEK) ...and glucose dehydrogenase (GDH) can be utilized as the NADPH recycling system for economic and efficient biocatalysis of (R)-4-chloro-3-hydroxybutanoate ((R)-CHBE), an important chiral pharmaceutical intermediate. The LEK and GDH was efficiently co-immobilized in mesocellular siliceous foams (MCFs) under microwave irradiation (CoLG-MIA). while they were also co-immobilized by entrapment in calcium alginate without MIA as control (CoLG-CA). The relative activity of CoLG-MIA was increased to 140% compared with that of free LEK. The CoLG-MIA exhibited a wider range of pH and temperature stabilities compared with other preparations. The thermal, storage and batch operational stabilities of microwave-assisted immobilized LEK-GDH were also improved. The NADPH recycling system exhibited the potential as the stable and efficient catalyst for the industrial preparation of (R)-CHBE.
β-Elemene (C15H24), a sesquiterpenoid compound isolated from the volatile oil of Curcuma wenyujin, has been proven to be effective for multiple cancers and is widely used in clinical treatment. ...Unfortunately, the β-elemene content in C. wenyujin is very low, which cannot meet market demands. Our previous research showed that methyl jasmonate (MeJA) induced the accumulation of β-elemene in C. wenyujin. However, the regulatory mechanism is unclear. In this study, 20 jasmonate ZIM-domain (JAZ) proteins in C. wenyujin were identified, which are the core regulatory factors of the JA signaling pathway. Then, the conservative domains, motifs composition, and evolutionary relationships of CwJAZs were analyzed comprehensively and systematically. The interaction analysis indicated that CwJAZs can form homodimers or heterodimers. Fifteen out of twenty CwJAZs were significantly induced via MeJA treatment. As the master switch of the JA signaling pathway, the CwMYC2-like protein has also been identified and demonstrated to interact with CwJAZ2/3/4/5/7/15/17/20. Further research found that the overexpression of the CwMYC2-like gene increased the accumulation of β-elemene in C. wenyujin leaves. Simultaneously, the expressions of HMGR, HMGS, DXS, DXR, MCT, HDS, HDR, and FPPS related to β-elemene biosynthesis were also up-regulated by the CwMYC2-like protein. These results indicate that CwJAZs and the CwMYC2-like protein respond to the JA signal to regulate the biosynthesis of β-elemene in C. wenyujin.
Calcineurin B-like protein interacting protein kinases (CIPKs) are vital elements in plant abiotic stress signaling pathways. However, the functional mechanism of CIPKs has not been understood ...clearly, especially in
, a new monocot model plant. In this study,
a
gene from
was characterized.
was downregulated by polyethylene glycol, NaCl, H
O
, and abscisic acid (ABA) treatments. Transgenic tobacco plants overexpressing
presented improved drought and salt tolerance, and displayed hypersensitive response to exogenous ABA. Further investigations revealed that BdCIPK31 functioned positively in ABA-mediated stomatal closure, and transgenic tobacco exhibited reduced water loss under dehydration conditions compared with the controls. BdCIPK31 also affected Na
/K
homeostasis and root K
loss, which contributed to maintain intracellular ion homeostasis under salt conditions. Moreover, the reactive oxygen species scavenging system and osmolyte accumulation were enhanced by
overexpression, which were conducive for alleviating oxidative and osmotic damages. Additionally, overexpression of
could elevate several stress-associated gene expressions under stress conditions. In conclusion, BdCIPK31 functions positively to drought and salt stress through ABA signaling pathway. Overexpressing
functions in stomatal closure, ion homeostasis, ROS scavenging, osmolyte biosynthesis, and transcriptional regulation of stress-related genes.
Germacrene A (GA) is a key intermediate for the synthesis of medicinal active compounds, especially for β-elemene, which is a broad-spectrum anticancer drug. The production of sufficient GA in the ...microbial platform is vital for the precursors supply of active compounds. In this study,
Escherichia coli
BL21 Star (DE3) was used as the host and cultivated in SBMSN medium, obtaining a highest yield of FPP. The GA synthase from
Lactuca sativa
(LTC2) exhibited the highest level of GA production. Secondly, two residues involved in product release (T410 and T392) were substituted with Ser and Ala, respectively, responsible for relatively higher activities. Next, substitution of selected residues S243 with Asn caused an increase in activity. Furthermore, I364K-T410S and T392A-T410S were created by combination with the beneficial mutation, and they demonstrated dramatically enhanced titers with 1.90-fold and per-cell productivity with 5.44-fold, respectively. Finally, the production titer of GA reached 126.4 mg/L, and the highest productivity was 7.02 mg/L.h by the I364K-T410S mutant in a shake-flask batch culture after fermentation for 18 h. To our knowledge, the productivity of the I364K-T410S mutant is the highest level ever reported. These results highlight a promising method for the industrial production of GA in
E. coli
, and lay a foundation for pathway reconstruction and the production of valuable natural sesquiterpenes.
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