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1.
Plasma membrane H+-ATPase (PM H+-ATPase, EC 3.6.1.3.) is a proton pump that is necessary to promote cell growth and ion fluxes across the plasma membrane. The main goal of this study was to evaluate the role of PM H+-ATPase isoform OsA7 expression in rice growth and nitrogen (N) accumulation using three genetically engineered lineages with artificial micro RNA (amiRNA) targeting OsA7 (osa7.1, osa7.2, and osa7.3). PM H+-ATPase isoform expression in rice shoots and roots (wild-type) revealed that OsA7 is highly expressed in roots and is the most highly expressed PM H+-ATPase isoform. The three osa7 lineages had lower fresh weight, grain yield, height, and 1000-grain weight compared to control IRS plants. The hydroponic experiment comprised three NO3− levels over 30 days: 0.2 mM NO3−–N, 2.0 mM NO3−–N, and NO3− starvation for 3 days. The three osa7 lineages had lower PM H+-ATPase and V-H+-PPase activity as compared to the IRS plants. The root and shoot fresh weights were lower in osa7 lineages. The root/shoot ratio was lower in the osa7 lineages cultivated without nitrogen for 3 days and with 0.2 mM of NO3−–N as compared to IRS, and did not change in plants cultivated with 2.0 mM NO3−–N. The total N concentration did not change in the three osa7 lineages as compared to IRS. Overall, the results indicate that OsA7 is important for rice growth, grain production, and root growth, but does not affect N accumulation, highlighting the importance of other PM H+-ATPase isoforms in N uptake. 相似文献
2.
Numerous studies with transgenic plants have demonstrated that overexpression of enzymes related to organic acid metabolism
under the control of CaMV 35S promoter increased organic acid exudation and Al-resistance. The synthesis of organic acids
requires a large carbon skeleton supply from leaf photosynthesis. Thus, we produced transgenic tobacco overexpressing cytosolic
malate dehydrogenase (MDH) cDNA from Arabidopsis thaliana ( amdh) and the MDH gene from Escherichia coli ( emdh), respectively, under the control of a leaf-specific light-inducible promoter (Rubisco small subunit promoter, PrbcS) in
the present study. Our data indicated that an increase (120–130%) in MDH-specific activity in leaves led to an increase in
malate content in the transgenic tobacco leaves and roots as well as a significant increase in root malate exudation compared
with the WT plants under the acidic (pH 4.5) conditions irrespective of 300 μM Al 3+ stress absence or presence. After being exposed to 25 μM Al 3+ in a hydroponic solution, the transgenic plants exhibited stronger Al-tolerance than WT plants and the degree of A1 tolerance
in the transgenic plants corresponded with the amount of malate secretion. When grown in an Al-stress perlite medium, the
transgenic tobacco lines showed better growth than the WT plants. The results suggested that overexpression of MDH driven
by the PrbcS promoter in transgenic plant leaves enhanced malate synthesis and improved Al-resistance. 相似文献
3.
The nitrate () transporter has been selected as an important gene maker in the process of environmental adoption in rice cultivars. In this work, we transferred another native OsNAR2.1 promoter with driving OsNAR2.1 gene into rice plants. The transgenic lines with exogenous pOsNAR2.1:OsNAR2.1 constructs showed enhanced OsNAR2.1 expression level, compared with wild type (WT), and 15N influx in roots increased 21%–32% in response to 0.2 mm and 2.5 mm and 1.25 mm 15NH 415NO 3. Under these three N conditions, the biomass of the pOsNAR2.1:OsNAR2.1 transgenic lines increased 143%, 129% and 51%, and total N content increased 161%, 242% and 69%, respectively, compared to WT. Furthermore in field experiments we found the grain yield, agricultural nitrogen use efficiency (ANUE), and dry matter transfer of pOsNAR2.1:OsNAR2.1 plants increased by about 21%, 22% and 21%, compared to WT. We also compared the phenotypes of pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines in the field, found that postanthesis N uptake differed significantly between them, and in comparison with the WT. Postanthesis N uptake (PANU) increased approximately 39% and 85%, in the pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines, respectively, possibly because OsNRT2.1 expression was less in the pOsNAR2.1:OsNAR2.1 lines than in the pOsNAR2.1:OsNRT2.1 lines during the late growth stage. These results show that rice NO 3– uptake, yield and NUE were improved by increased OsNAR2.1 expression via its native promoter. 相似文献
5.
Plant vacuolar Na +/H + antiporter genes play significant roles in salt tolerance. However, the roles of the chrysanthemum vacuolar Na +/H + antiporter genes in salt stress response remain obscure. In this study, we isolated and characterized a novel vacuolar Na +/H + antiporter gene DgNHX1 from chrysanthemum. The DgNHX1 sequence contained 1920 bp with a complete open reading frame of 1533 bp encoding a putative protein of 510 amino acids with a predicted protein molecular weight of 56.3 kDa. DgNHX1 was predicted containing nine transmembrane domains. Its expression in the chrysanthemum was up-regulated by salt stress, but not by abscisic acid (ABA). To assess roles of DgNHX1 in plant salt stress responses, we performed gain-of-function experiment. The DgNHX1-overexpression tobacco plants showed significant salt tolerance than the wild type (WT). The transgenic lines exhibited more accumulation of Na + and K + under salt stress. These findings suggest that DgNHX1 plays a positive regulatory role in salt stress response. 相似文献
6.
Plant tissue culture technology is being widely used for large-scale, rapid, clonal multiplication and genetic transformation in cassava. The main limitation of this technology is the period of acclimation of the fragile in vitro plants after they have been multiplied or regenerated. Most losses of in vitro plants occur when the plantlets are moved directly from the test tubes to the ex vitro conditions. Our aim was to design a simple, rapid, low-maintenance hydroponic system to improve survival rate of transplanting to the ex vitro conditions through the rapid acclimation process of in vitro plants. In this paper, we have developed a simple hydroponic system to accelerate the cassava acclimation and multiplication process. This system considerably increased the survival percentage of in vitro and/or transgenic lines and reduces the time requirement for multiplication by hydroponic acclimation. In order to assess the effectiveness of the acclimation of seedlings on their establishment, we analyzed plant growth and field survival rate with response to different nitrogen (N) sources using different cassava accessions. Nitrogen sources of NO 3 ? and NH 4NO 3 increased plant growth and root length compared to NH 4 + alone, or water treatments. The greenhouse and field survivability of N-hardened plants, including transgenic lines, were significantly different in growth and development. We present a simple NO 3 ? hydroponic acclimation system that can be quickly and cheaply constructed and used by the cassava community around the world. The efficiency of our proposed N hydroponic acclimation system is validated in the transgenic development pipeline which will enhance the cassava molecular breeding. 相似文献
7.
Tobacco leaf discs were transformed with a plasmid pBIBnNHX1, containing the selectable marker neomycin phosphotransferase gene ( nptII) and Na +/H + vacuolar antiporter gene from Brassica napus ( BnNHX1), via Agrobacterium tumefaciens-mediated transformation. Thirty-two independent transgenic plants were regenerated. Polymerase chain reaction (PCR) and Southern blot analyses confirmed that the BnNHX1 gene had integrated into plant genome and Northern blot analysis revealed the transgene expression at various levels in transgenic plants. Transgenic plants expressing BnNHX1 had enhanced salt tolerance and could grow and produce seeds normally in the presence of 200 mM NaCl. Analysis for the T 1 progenies derived from seven independent transgenic primary transformants expressing BnNHX1 showed that the transgenes in most tested independent T 1 lines were inherited at Mendelian 3:1 segregation ratios. Transgenic T 1 progenies could express BnNHX1 and had salt tolerance at levels comparable to their T 0 parental lines. This study implicates that the BnNHX1 gene represents a promising candidate in the development of crops for enhanced salt tolerance by genetic engineering. 相似文献
8.
A cDNA ( SsCAX1) encoding a tonoplast-localised Ca 2+/H + exchanger was isolated from a C 3 halophyte Suaeda salsa (L.). To clarify the role of SsCAX1 in plant salt tolerance, Arabidopsis plants expressing SsCAX1 were treated with NaCl. Transgenic Arabidopsis plants displayed decreased salt tolerance. Although Na + content was close to wild-type plants, transgenic plants accumulated more Ca 2+ and retained less K + in leaves than the wild-type plants in salinity. Furthermore, transgenic lines held higher leaf membrane leakage than wild-type
lines under NaCl treatment. In addition, transgenic plants showed a 23% increase in vacuolar H +-ATPase activity compared with wild-type plants in normal condition. But the leaf V-H +-ATPase activity had subtle changes in transgenic plants, while significantly increased in wild-type plants under saline condition.
These results suggested that regulated expression of Ca 2+/H + antiport was critical for maintenance of cation homeostasis and activity of V-H +-ATPase under saline condition. 相似文献
10.
The effect of NH 4+/NO 3− availability on nitrate reductase (NR) activity in Phragmites australis and Glyceria maxima was studied in sand and water cultures with the goal to characterise the relationship between NR activity and NO 3− availability in the rhizosphere and to describe the extent to which NH 4+ suppresses the utilization of NO 3− in wetland plants.The NR activity data showed that both wetland helophytes are able to utilize NO 3−. This finding was further supported by sufficient growth observed under the strict NO 3− nutrition. The distribution of NR activity within plant tissues differed between species. Phragmites was proved to be preferential leaf NO 3− reducer with high NR activity in leaves (NR max > 6.5 μmol NO 2− g dry wt −1 h −1) under all N treatments, and therefore Phragmites seems to be good indicator of NO 3− availability in flooded sediment. In the case of Glyceria the contribution of roots to plant NO 3− reduction was higher, especially in sand culture. Glyceria also tended to accumulate NO 3− in non-reduced form, showing generally lower leaf NR activity levels. Thus, the NR activity does not necessarily correspond with plant ability to take up NO 3− and grow under NO 3−-N source. Moreover, the species differed significantly in the content of compounds interfering with NR activity estimation. Glyceria, but not Phragmites, contained cyanogenic glycosides releasing cyanide, the potent NR inhibitor. It clearly shows that the use of NR activity as a marker of NO 3− utilization in individual plant species is impossible without the precise method optimisation. 相似文献
11.
Summary. The vacuolar H +-translocating inorganic pyrophosphatase (H +-PPase) uses pyrophosphate as substrate to generate the proton electrochemical gradient across the vacuolar membrane to acidify
vacuoles in plant cells. The heterologous expression of H +-PPase genes ( TsVP from Thellungiella halophila and AVP1 from Arabidopsis thaliana) improved the salt tolerance of tobacco plants. Under salt stress, the transgenic seedlings showed much better growth and
greater fresh weight than wild-type plants, and their protoplasts had a normal appearance and greater vigor. The cytoplasmic
and vacuolar pH in transgenic and wild-type cells were measured with a pH-sensitive fluorescence indicator. The results showed
that heterologous expression of H +-PPase produced an enhanced proton electrochemical gradient across the vacuolar membrane, which accelerated the sequestration
of sodium ions into the vacuole. More Na + accumulated in the vacuoles of transgenic cells under salt (NaCl) stress, revealed by staining with the fluorescent indicator
Sodium Green. It was concluded that the tonoplast-resident H +-PPase plays important roles in the maintenance of the proton gradient across the vacuolar membrane and the compartmentation
of Na + within vacuoles, and heterologous expression of this protein enhanced the electrochemical gradient across the vacuolar membrane,
thereby improving the salt tolerance of tobacco cells.
Correspondence: J.-R. Zhang, School of Life Science, Shandong University, 27 Shanda South Road, Jinan, People’s Republic of
China 250100. 相似文献
12.
Nitrogen assimilation was studied in the deciduous, perennial climber Clematis vitalba. When solely supplied with NO 3– in a hydroponic system, growth and N-assimilation characteristics were similar to those reported for a range of other species. When solely supplied with NH 4+, however, nitrate reductase (NR) activity dramatically increased in shoot tissue, and particularly leaf tissue, to up to three times the maximum level achieved in NO 3– supplied plants. NO 3– was not detected in plant material that had been solely supplied with NH 4+, there was no NO 3– contamination of the hydroponic system, and the NH 4+-induced activity did not occur in tobacco or barley grown under similar conditions. Western Blot analysis revealed that the induction of NR activity, either by NO 3– or NH 4+, was matched by NR and nitrite reductase protein synthesis, but this was not the case for the ammonium assimilation enzyme glutamine synthetase. Exposure of leaf disks to N revealed that NO 3– assimilation was induced in leaves directly by NO 3– and NH 4+ but not glutamine. Our results suggest that the NH 4+-induced potential for NO 3– assimilation occurs when externally sourced NH 4+ is assimilated in the absence of any NO 3– assimilation. These data show that the potential for nitrate assimilation in C. vitalba is induced by a nitrogenous compound in the absence of its substrate and suggest that NO 3– assimilation in C. vitalba may have a significant role beyond the supply of reduced N for growth. 相似文献
14.
Mutation of the nuclear gene sid disables chlorophyll degradation during leaf senescence in the pasture grass Festuca pratensis. This study investigated the effect of the mutation on photosynthesis and on leaf and whole plant growth under a range of nitrogen regimes. When plants were cultivated in a static hydroponic system, the chlorophyll content of fourth leaves of the stay-green mutant Bf993 remained virtually unchanged from full expansion to complete senescence, while tissue of the wild-type (cv. Rossa) became completely yellow. The retention of chlorophyll in Bf993 was not associated with maintenance of photosynthetic activity as shown by rates of light-saturated CO 2 fixation and apparent quantum efficiency. Higher levels of total N in senescing leaves of Bf993 than in Rossa indicated reduced nitrogen remobilization in the mutant. When using a range of [NH 4NO 3], dry matter production and tillering Mere lower for Bf993 at all but the highest [NH 4NO 3, which was supra-optimal for the wild type. In contrast to the static system, where fluctuations in N supply occurred, growth and [NO 3?] uptake were similar in mutant and wild type when [NO 3?] was continuously maintained by a flowing solution culture system. The results are discussed in relation to the role of N supply and the effect of the stay-green mutation on N recycling. 相似文献
15.
Salinity is a major abiotic stress factor limiting plant growth and productivity. One possible method to enhance plant salt-resistance
is to compartmentalize sodium ions away from the cytosol. In the present work, a vacuolar Na +/H + antiporter gene AtNHX1 from Arabidopsis thaliana, was transferred into Populus × euramericana ‘Neva’ by Agrobacterium tumefaciens in order to enhance poplar salt-resistance. The results showed that the transgenic poplar were more resistant to NaCl than
the wild-type (WT) in greenhouse condition. Compared with the WT, plant growth and photosynthetic capacity of the transgenic
plants were enhanced, and the transgenic plants accumulated more Na + and K + in roots and leaves under the same NaCl condition, whereas malondialdehyde and relative electrical conductivity were lower.
All of these properties of the transgenic poplar were likely to be a consequence of the overexpression of AtNHX1 caused Na + sequestration in the vacuoles and improved K + absorption, thus reducing their toxic effects. These results indicated overexpression of the AtNHX1 enhanced salt-resistance of poplar, and AtNHX1 played an important role in the compartmentation of Na + into the vacuoles. Therefore, this study provides an effective way for improving salt resistance in trees. 相似文献
17.
A putative vacuolar Na +/H + antiporter gene ( SsNHX1) was isolated from the halophyte Salsola soda using the rapid amplification of cDNA ends method. Highly conserved regions of plant vacuolar Na +/H + antiporter, including amiloride-binding domain, NHE (Na +/H + exchange) domain, and 12 transmembrane segments, were found in the deduced amino acid sequence of SsNHX1. Multiple alignments of vacuolar Na +/H + antiporters showed that SsNHX1 shared high identity with other plant vacuolar Na +/H + antiporters. Phylogenetic relationship analysis indicated that SsNHX1 was clustered into the vacuolar Na +/H + antiporter group. Taken together, these results suggest that SsNHX1 is a new member of the vacuolar Na +/H + antiporter family. The effective expression of SsNHX1 in alfalfa ( Medicago sativa L.) enhanced the salt tolerance of transgenic alfalfa which could grow in high concentrations of NaCl (up to 400 mM) over
50 days. This was the highest level of salt tolerance reported in transgenic plants. A further analysis of the physiological
characteristics of transgenic and wild-type plants, including the Na + and K + contents, superoxide dismutase activity, the rate of electrolyte leakage, and the proline content, showed that large amounts
of Na + in the cytoplasm of leaves were transported into vacuoles by the exogenous Na +/H + antiporter, which averted the toxic effects of Na + to the cell of transgenic alfalfa. 相似文献
18.
A network of long-term monitoring sites on nitrogen (N) input and output of forests across Germany showed that a number of Germany's forests are subject to or are experiencing N saturation and that spruce ( Picea abies) stands have high risk. Our study was aimed at (1) quantifying the changes in gross rates of microbial N cycling and retention processes in forest soils along an N enrichment gradient and (2) relating the changes in soil N dynamics to N losses. We selected spruce sites representing an N enrichment gradient (indicated by leaching : throughfall N ratios) ranging from 0.04–0.13 (low N),≤0.26 (intermediate N enrichment) to≥0.42 (highly N enriched). To our knowledge, our study is the first to report on mechanistic changes in gross rates of soil N cycling and abiotic NO 3− retention under ambient N enrichment gradient. Gross N mineralization, NH 4+ immobilization, gross nitrification, and NO 3− immobilization rates increased up to intermediate N enrichment level and somewhat decreased at highly N-enriched condition. The turnover rates of NH 4+ and microbial N pools increased while the turnover rates of the NO 3− pool decreased across the N enrichment gradient. Abiotic immobilization of NH 4+ did not differ across sites and was lower than that of NO 3−. Abiotic NO 3− immobilization decreased across the N enrichment gradient. Microbial assimilation and turnover appeared to contribute largely to the retention of NH 4+. The increasing NO 3− deposition and decreasing turnover rates of the NO 3− pool, combined with decreasing abiotic NO 3− retention, possibly contributed to increasing NO 3− leaching and gaseous emissions across the N enrichment gradient. The empirical relationships of changes in microbial N cycling across the N enrichment gradient may be integrated in models used to predict responses of forest ecosystems (e.g. spruce) to increasing N deposition. 相似文献
19.
5‐Aminolevulinic acid (5‐ALA) has been suggested for improving plant salt tolerance via exogenous application. In this study, we used a transgenic canola ( Brassica napus), which contained a constituted gene YHem1 and biosynthesized more 5‐ALA, to study salt stress responses. In a long‐term pot experiment, the transgenic plants produced higher yield under 200 mmol L ?1 NaCl treatment than the wild type (WT). In a short‐term experiment, the YHem1 transformation accelerated endogenous 5‐ALA metabolism, leading to more chlorophyll accumulation, higher diurnal photosynthetic rates and upregulated expression of the gene encoding Rubisco small subunit. Furthermore, the activities of antioxidant enzymes, including superoxide dismutase, guaiacol peroxidase, catalase and ascorbate peroxidase, were significantly higher in the transgenic plants than the WT, while the levels of O 2· ? and malondialdehyde were lower than the latter. Additionally, the Na + content was higher in the transgenic leaves than that in the WT under salinity, but K + and Cl ? were significantly lower. The levels of N, P, Cu, and S in the transgenic plants were also significantly lower than those in the WT, but the Fe content was significantly improved. As the leaf Fe content was decreased by salinity, it was suggested that the stronger salt tolerance of the transgenic plants was related to the higher Fe acquisition. Lastly, YHem1 transformation improved the leaf proline content, but salinity decreased rather than increased it. The content of free amino acids and soluble sugars was similarly decreased as salinity increased, but it was higher in the transgenic plants than that in the WT. 相似文献
20.
This study examined the effects of nitrogen (N) fertilizer reduction on the carbon (C) metabolism and yield of Coreopsis tinctoria. A two-year (2020–2021) hydroponic experiment was conducted in accordance with a randomized complete group design with five N levels [0.875 mM Ca(NO3)2 (N1), 1.750 mM Ca(NO3)2 (N2), 3.500 mM Ca(NO3)2 (N3), 7.000 mM Ca(NO3)2 (N4), and 14.000 mM Ca(NO3)2 (N5)] and three replications. The results showed that low N significantly affected the functional leaf weight, C metabolism, and flower bud (or flower) numbers of C. tinctoria at harvest. Lower-N levels, especially those of the N2 treatment, significantly increased Rubisco, sucrose synthase (SS), sucrose phosphate synthase (SPS), soluble acid invertase (SAI), glucose 6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6PGDH) activity and maintained the flower number of C. tinctoria. In addition, the balance of carbohydrates (sucrose, starch, glucose, and fructose) and ATP contents was more efficiently maintained under relatively low-N levels. These findings might suggest that reduced application of N fertilizer affects the C metabolism of leaves and maintains the number of flowers in Coreopsis tinctoria. Applying relatively low-N fertilizer levels is also a promising cultivation strategy for C. tinctoria. 相似文献
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