NAC (NAM, ATAF, and CUC) transcription factors play important roles in plant biological processes, including phytohormone homeostasis, plant development, and in responses to various environmental ...stresses.
TaNAC29 was introduced into Arabidopsis using the Agrobacterium tumefaciens-mediated floral dipping method. TaNAC29-overexpression plants were subjected to salt and drought stresses for examining gene functions. To investigate tolerant mechanisms involved in the salt and drought responses, expression of related marker genes analyses were conducted, and related physiological indices were also measured. Expressions of genes were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR).
A novel NAC transcription factor gene, designated TaNAC29, was isolated from bread wheat (Triticum aestivum). Sequence alignment suggested that TaNAC29 might be located on chromosome 2BS. TaNAC29 was localized to the nucleus in wheat protoplasts, and proved to have transcriptional activation activities in yeast. TaNAC29 was expressed at a higher level in the leaves, and expression levels were much higher in senescent leaves, indicating that TaNAC29 might be involved in the senescence process. TaNAC29 transcripts were increased following treatments with salt, PEG6000, H2O2, and abscisic acid (ABA). To examine TaNAC29 function, transgenic Arabidopsis plants overexpressing TaNAC29 were generated. Germination and root length assays of transgenic plants demonstrated that TaNAC29 overexpression plants had enhanced tolerances to high salinity and dehydration, and exhibited an ABA-hypersensitive response. When grown in the greenhouse, TaNAC29-overexpression plants showed the same tolerance response to salt and drought stresses at both the vegetative and reproductive period, and had delayed bolting and flowering in the reproductive period. Moreover, TaNAC29 overexpression plants accumulated lesser malondialdehyde (MDA), H2O2, while had higher superoxide dismutase (SOD) and catalase (CAT) activities under high salinity and/or dehydration stress.
Our results demonstrate that TaNAC29 plays important roles in the senescence process and response to salt and drought stresses. ABA signal pathway and antioxidant enzyme systems are involved in TaNAC29-mediated stress tolerance mechanisms.
Field or laboratory measurements are commonly conducted to determine phthalates concentrations in spaces. This study investigated the association between various influencing factors and indoor ...phthalates concentrations. Back-propagation (BP) Neural Network was employed to verify a prediction model of indoor phthalates concentration with 80% of experimental data and 20% remaining data. The validation of remaining data shows a reasonable accuracy for model application, where the ratios of standard deviations were all greater than 0.45, most ERMS were close to 0 and all the EMR were less than 15.5%. In addition, we used relevant data from the China, Children, Homes, Health (CCHH) study conducted in Tianjin for further inspection. The prediction on di (2-ethylhexyl) phthalate (DEHP) concentration was performed, which indicated a high accuracy. Furthermore, the Monte-Carlo simulation was applied to quantify the effect of temperature on phthalates concentration combining with the prediction model. When the temperature increment value was 4°C, the average relative decrease ratio of dibutyl phthalate (DBP), DEHP, diisobutyl phthalate (DIBP) concentration was about 7.8%, 12.8% and 9.3%, respectively. The findings have established the validity of the prediction model and provided a quantification of the influence of temperature on the concentration of phthalates in the indoor dust phase.
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.
Increasing the provitamin A content in staple crops via carotenoid metabolic engineering is one way to address vitamin A deficiency. In this work a combination of methods was applied to specifically ...increase β-carotene content in wheat by metabolic engineering. Endosperm-specific silencing of the carotenoid hydroxylase gene (TaHYD) increased β-carotene content 10.5-fold to 1.76 μg g–1 in wheat endosperm. Overexpression of CrtB introduced an additional flux into wheat, accompanied by a β-carotene increase of 14.6-fold to 2.45 μg g–1. When the “push strategy” (overexpressing CrtB) and “block strategy” (silencing TaHYD) were combined in wheat metabolic engineering, significant levels of β-carotene accumulation were obtained, corresponding to an increase of up to 31-fold to 5.06 μg g–1. This is the first example of successful metabolic engineering to specifically improve β-carotene content in wheat endosperm through a combination of methods and demonstrates the potential of genetic engineering for specific nutritional enhancement of wheat.
Subunit pair 1Dx5 + 1Dy10 was recognized as superior subunit combination in wheat and contained an extra repetitive-domain cysteine residue in 1Dx5 that was important for understanding the formation ...of dough viscoelasticity. In this research, one specific serine codon of the 1Ax1 gene corresponding to the extra cysteine residue of 1Dx5 was substituted by a cysteine codon through site-directed mutagenesis. Four homozygous transgenic lines (T
) expressing the mutant 1Ax1 gene (mut1Ax1) were produced. Their greater dough strength and stability were confirmed by mixograph and were associated with highly increased gluten index, larger amounts of gluten macropolymers, larger size distribution for glutenin macropolymer particles and varied sodium-dodecyl-sulfate sedimentation volumes, compared with those of the one line expressing wild 1Ax1 that had similar expression level of transgene. The contents of β-sheets in dough and disulfide groups in gluten of the mut1Ax1 transgenic lines were significantly increased. The microstructure of dough mixed to peak showed a more continuous gluten matrix in the mutant transgenic lines than the one line mentioned-above. It was concluded that the extra cysteine residue of mutant 1Ax1 subunit plays a positive role in contributing to dough strength and stability of wheat by cross-linking into gluten aggregates through inter-chain disulfide bonds.
Avenin-like b proteins are a small family of wheat storage proteins, each containing 18 or 19 cysteine residues. The role of these proteins, with high numbers of cysteine residues, in determining the ...functional properties of wheat flour is unclear. In the present study, two transgenic lines of the bread wheat overexpressing avenin-like b gene were generated to investigate the effects of Avenin-like b proteins on dough mixing properties. Sodium dodecyl sulfate sedimentation (SDSS) test and Mixograph analysis of these lines demonstrated that overexpression of Avenin-like b proteins in both transgenic wheat lines significantly increased SDSS volume and improved dough elasticity, mixing tolerance and resistance to extension. These changes were associated with the increased proportion of polymeric proteins due to the incorporation of overexpressed Avenin-like b proteins into the glutenin polymers. The results of this study were critical to confirm the hypothesis that Avenin-like b proteins could be integrated into glutenin polymers by inter-chain disulphide bonds, which could help understand the mechanism behind strengthening wheat dough strength.
Wheat end-use quality mainly derives from two interrelated characteristics: the compositions of gluten proteins and grain hardness. The composition of gluten proteins determines dough rheological ...properties and thus confers the unique viscoelastic property on dough. One group of gluten proteins, high molecular weight glutenin subunits (HMW-GS), plays an important role in dough functional properties. On the other hand, grain hardness, which influences the milling process of flour, is controlled by Puroindoline a (Pina) and Puroindoline b (Pinb) genes. However, little is known about the combined effects of HMW-GS and PINs on dough functional properties. In this study, we crossed a Pina-expressing transgenic line with a 1Ax1-expressing line of durum wheat and screened out lines coexpressing 1Ax1 and Pina or lines expressing either 1Ax1 or Pina. Dough mixing analysis of these lines demonstrated that expression of 1Ax1 improved both dough strength and over-mixing tolerance, while expression of PINA detrimentally affected the dough resistance to extension. In lines coexpressing 1Ax1 and Pina, faster hydration of flour during mixing was observed possibly due to the lower water absorption and damaged starch caused by PINA expression. In addition, expression of 1Ax1 appeared to compensate the detrimental effect of PINA on dough resistance to extension. Consequently, coexpression of 1Ax1 and PINA in durum wheat had combined effects on dough mixing behaviors with a better dough strength and resistance to extension than those from lines expressing either 1Ax1 or Pina. The results in our study suggest that simultaneous modulation of dough strength and grain hardness in durum wheat could significantly improve its breadmaking quality and may not even impair its pastamaking potential. Therefore, coexpression of 1Ax1 and PINA in durum wheat has useful implications for breeding durum wheat with dual functionality (for pasta and bread) and may improve the economic values of durum wheat.
B-Type avenin-like genes and proteins were characterized in 23 species of
Triticeae. Southern blot analysis showed that the avenin-like genes belong to a multigene family. RT-PCR showed expression ...only in developing endosperms of wheat and related species, between 3 and 22
DPA (days post anthesis) with a peak between 11 and 15
DPA in wheat. The encoded proteins are cysteine-rich, containing 18–19 cysteine residues. An avenin-like protein from wheat was expressed in
Escherichia coli, purified and used to raise polyclonal antibodies. These antibodies were used to detect b-type avenin-like proteins in endosperms of wheat and related species by western blotting.
The WRKY transcription factors have been reported to be involved in various plant physiological and biochemical processes. In this study, we successfully assembled 10 unigenes from expressed sequence ...tags (ESTs) of wheat and designated them as TaWRKY44-TaWRKY53, respectively. Among these genes, a subgroup I gene, TaWRKY44, was found to be upregulated by treatments with PEG6000, NaCl, 4°C, abscisic acid (ABA), H2O2 and gibberellin (GA). The TaWRKY44-GFP fusion protein was localized to the nucleus of onion epidermal cells, and TaWRKY44 was able to bind to the core DNA sequences of TTGACC and TTAACC in yeast. The N-terminal of TaWRKY44 showed transcriptional activation activity. Expression of TaWRKY44 in tobacco plants conferred drought and salt tolerance and transgenic tobacco exhibited a higher survival rate, relative water content (RWC), soluble sugar, proline and superoxide dismutase (SOD) content, as well as higher activities of catalase (CAT) and peroxidase (POD), but less ion leakage (IL), lower contents of malondialdehyde (MDA), and H2O2. In addition, expression of TaWRKY44 also increased the seed germination rate in the transgenic lines under osmotic stress conditions while exhibiting a lower H2O2 content and higher SOD, CAT, and POD activities. Expression of TaWRKY44 upregulated the expression of some reactive oxygen species (ROS)-related genes and stress-responsive genes in tobacco under osmotic stresses. These data demonstrate that TaWRKY44 may act as a positive regulator in drought/salt/osmotic stress responses by either efficient ROS elimination through direct or indirect activation of the cellular antioxidant systems or activation of stress-associated gene expression.
The quality of wheat flour is largely determined by the properties of gluten proteins. Chemical components that influence gluten proteins are used as flour improvers in the flour industry. In this ...study, tannins which are natural occurring polyphenols were found to improve dough mixing properties. The effects of tannins on the physicochemical and structural properties of gluten proteins were examined, and the results showed that tannins promoted the non-covalent interactions among gluten proteins, although they induced SH/SS interchange reactions in the dough. The β-turn and α-helix conformations were increased, whereas the β-sheet conformation was decreased in dough containing tannins as detected by FTIR. Moreover, the addition of tannins promoted the aggregation of gluten proteins, modified the microstructure of gluten networks, and improved the mixing properties. The positive effects of tannins on dough properties implied the potential of tannins as a new flour improver.
•Tannins improved the dough mixing properties of wheat flour.•Tannin addition led to a more compact gluten microstructure.•Reduction of disulfide bonds by tannins did not result in poorer dough quality.•Tannins improved gluten protein interactions through hydrogen bonds.
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