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Deoxyhypusine synthase (DHS) mediates the first of two enzymatic reactions required for the post-translational activation of eukaryotic translation initiation factor 5A (eIF5A), which in turn is thought to facilitate translation of specific mRNAs. Analyses of GUS activity in transgenic Arabidopsis plants expressing the GUS reporter gene under regulation of the promoter for AtDHS revealed that the expression of DHS changes both spatially and temporally as development progresses. In particular, DHS is expressed not only in rosette leaves, but also in the anthers of developing flowers. To determine the role of DHS in leaves, transgenic plants in which DHS was selectively suppressed in rosettes of Arabidopsis plants were prepared. This was achieved by expressing AtDHS 3'-UTR cDNA as a transgene under regulation of the promoter for AtRbcS2, a gene encoding the small subunit of Rubisco. The dominant phenotypic traits of the DHS-suppressed plants proved to be a dramatic enhancement of both vegetative and reproductive growth. As well, the onset of leaf senescence in the DHS-suppressed plants was delayed by approximately 1 week, but there was no change in the timing of bolting. In addition, there was no evidence for the negative pleiotropic effects, including stunted reproductive growth and reduced seed yield, noted previously for transgenic plants in which DHS was constitutively suppressed. The results indicate that DHS plays a pivotal role in both growth and senescence. 相似文献
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Surya Kant David Burch Pieter Badenhorst Rajasekaran Palanisamy John Mason German Spangenberg 《PloS one》2015,10(1)
Delay of leaf senescence through genetic modification can potentially improve crop yield, through maintenance of photosynthetically active leaves for a longer period. Plant growth hormones such as cytokinin regulate and delay leaf senescence. Here, the structural gene (IPT) encoding the cytokinin biosynthetic enzyme isopentenyltransferase was fused to a functionally active fragment of the AtMYB32 promoter and was transformed into canola plants. Expression of the AtMYB32xs::IPT gene cassette delayed the leaf senescence in transgenic plants grown under controlled environment conditions and field experiments conducted for a single season at two geographic locations. The transgenic canola plants retained higher chlorophyll levels for an extended period and produced significantly higher seed yield with similar growth and phenology compared to wild type and null control plants under rainfed and irrigated treatments. The yield increase in transgenic plants was in the range of 16% to 23% and 7% to 16% under rainfed and irrigated conditions, respectively, compared to control plants. Most of the seed quality parameters in transgenic plants were similar, and with elevated oleic acid content in all transgenic lines and higher oil content and lower glucosinolate content in one specific transgenic line as compared to control plants. The results suggest that by delaying leaf senescence using the AtMYB32xs::IPT technology, productivity in crop plants can be improved under water stress and well-watered conditions. 相似文献
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Molecular tailoring of farnesylation for plant drought tolerance and yield protection 总被引:1,自引:0,他引:1
Wang Y Ying J Kuzma M Chalifoux M Sample A McArthur C Uchacz T Sarvas C Wan J Dennis DT McCourt P Huang Y 《The Plant journal : for cell and molecular biology》2005,43(3):413-424
Protecting crop yield under drought stress is a major challenge for modern agriculture. One biotechnological target for improving plant drought tolerance is the genetic manipulation of the stress response to the hormone abscisic acid (ABA). Previous genetic studies have implicated the involvement of the beta-subunit of Arabidopsis farnesyltransferase (ERA1) in the regulation of ABA sensing and drought tolerance. Here we show that molecular manipulation of protein farnesylation in Arabidopsis, through downregulation of either the alpha- or beta-subunit of farnesyltransferase enhances the plant's response to ABA and drought tolerance. To test the effectiveness of tailoring farnesylation in a crop plant, transgenic Brassica napus carrying an ERA1 antisense construct driven by a drought-inducible rd29A promoter was examined. In comparison with the non-transgenic control, transgenic canola showed enhanced ABA sensitivity, as well as significant reduction in stomatal conductance and water transpiration under drought stress conditions. The antisense downregulation of canola farnesyltransferase for drought tolerance is a conditional and reversible process, which depends on the amount of available water in the soil. Furthermore, transgenic plants were more resistant to water deficit-induced seed abortion during flowering. Results from three consecutive years of field trial studies suggest that with adequate water, transgenic canola plants produced the same amount of seed as the parental control. However, under moderate drought stress conditions at flowering, the seed yields of transgenic canola were significantly higher than the control. Using protein farnesyltransferase as an effective target, these results represent a successful demonstration of engineered drought tolerance and yield protection in a crop plant under laboratory and field conditions. 相似文献
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Antisense suppression of deoxyhypusine synthase in tomato delays fruit softening and alters growth and development
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The effects of suppressing deoxyhypusine synthase (DHS) have been examined in tomato (Solanum lycopersicum cv UCT5). DHS mediates the first of two sequential enzymatic reactions that activate eukaryotic translation initiation factor-5A (eIF-5A) by converting a conserved Lys to the unusual amino acid, deoxyhypusine. DHS protein levels were suppressed in transgenic plants by expressing the 3'-untranslated region of tomato DHS under regulation of the constitutive cauliflower mosaic virus promoter. Fruit from the transgenic plants ripened normally, but exhibited delayed postharvest softening and senescence that correlated with suppression of DHS protein levels. Northern-blot analysis indicated that all four gene family members of tomato eIF-5A are expressed in fruit, and that three are up-regulated in parallel with enhancement of DHS mRNA as the fruit begin to senesce and soften. Transgenic plants in which DHS was more strongly suppressed were male sterile, did not produce fruit, and had larger, thicker leaves with enhanced levels of chlorophyll. The activity of PSII was 2 to 3 times higher in these transgenic leaves than in corresponding leaves of wild-type plants, and there was also enhanced deposition of starch in the stems. The data collectively indicate that suppression of DHS has pleiotropic effects on growth and development of tomato. This may, in turn, reflect the fact that there is a single DHS gene in tomato and that its cognate protein is involved in the activation of four distinct isoforms of eIF-5A. 相似文献
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Murillo I Roca R Bortolotti C Segundo BS 《The Plant journal : for cell and molecular biology》2003,36(3):330-341
Expression of pathogenesis-related (PR) genes is part of the plant's natural defense response against pathogen attack. To study the in vivo role and function of the maize PRms protein, tobacco plants were transformed with the PRms cDNA under the control of the CaMV35S promoter. Transgenic tobacco plants grow faster and yield more leaf and seed biomass. By using immunoelectron microscopy, we found that PRms is associated with plasmodesmata in leaves of transgenic tobacco plants. Furthermore, we found that activation of sucrose efflux from photosynthetically active leaves and accumulation of higher levels of sucrose in leaf tissues are characteristic features of PRms tobacco plants. This, in turn, results in the constitutive expression of endogenous tobacco PR genes and resistance to phytopathogens. The expression of multiple plant defense genes can then be achieved by using a single transgene. These data provide a new approach for engineering disease-resistant plants while simultaneously improving plant yield and productivity through the modification of photoassimilate partitioning. 相似文献
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XVSAP1, a gene isolated from a dehydrated Xerophyta viscosa cDNA library, was transformed into Arabidopsis thaliana by Ti plasmid-mediated transformation under the control of a cauliflower mosaic virus 35S promoter, a nos terminator and bar gene selection. Expression of XVSAP1 in Arabidopsis led to constitutive accumulation of the corresponding protein in the leaves. Transgenic Arabidopsis grown in tissue culture maintained higher growth rates during osmotic, high-salinity and high temperature stress, respectively. Non-transgenic plants had shorter roots, leaf expansion was inhibited and leaves were more chlorotic than those of the transgenic plants. This study demonstrates that XVSAP1 has a significant impact on dehydration, salinity and high-temperature stress tolerance in Arabidopsis. 相似文献
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Accumulation of a Brazil nut albumin in seeds of transgenic canola results in enhanced levels of seed protein methionine 总被引:14,自引:0,他引:14
Susan B. Altenbach Chiung-Chi Kuo Lisa C. Staraci Karen W. Pearson Connie Wainwright Anca Georgescu Jeffrey Townsend 《Plant molecular biology》1992,18(2):235-245
We have increased the methionine content of the seed proteins of a commercial winter variety of canola by expressing a chimeric gene encoding a methionine-rich seed protein from Brazil nut in the seeds of transgenic plants. Transgenic canola seeds accumulate the heterologous methionine-rich protein at levels which range from 1.7% to 4.0% of the total seed protein and contain up to 33% more methionine. The precursor of the methionine-rich protein is processed correctly in the seeds, resulting in the appearance of the mature protein in the 2S protein fraction. The 2S methionine-rich protein accumulates in the transgenic seeds at the same time in development as the canola 11S seed proteins and disappears rapidly upon germination of the seed. The increase in methionine in the canola seed proteins should increase the value of canola meal which is used in animal feed formulations. 相似文献
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Water movement across cellular membranes is regulated largely by a family of water channel proteins called aquaporins (AQPs).
Since several abiotic stresses such as, drought, salinity and freezing, manifest themselves via altering water status of plant
cells and are linked by the fact that they all result in cellular dehydration, we overexpressed an AQP (tonoplast intrinsic
protein) from Panax ginseng, PgTIP1, in transgenic Arabidopsis
thaliana plants to test its role in plant’s response to drought, salinity and cold acclimation (induced freezing tolerance). Under
favorable conditions, PgTIP1 overexpression significantly increased plant growth as determined by the biomass production, and leaf and root morphology.
PgTIP1 overexpression had beneficial effect on salt-stress tolerance as indicated by superior growth status and seed germination
of transgenic plants under salt stress; shoots of salt-stressed transgenic plants also accumulated greater amounts of Na+ compared to wild-type plants. Whereas PgTIP1 overexpression diminished the water-deficit tolerance of plants grown in shallow (10 cm deep) pots, the transgenic plants
were significantly more tolerant to water stress when grown in 45 cm deep pots. The rationale for this contrasting response,
apparently, comes from the differences in the root morphology and leaf water channel activity (speed of dehydration/rehydration)
between the transgenic and wild-type plants. Plants overexpressed with PgTIP1 exhibited lower (relative to wild-type control) cold acclimation ability; however, this response was independent of cold-regulated
gene expression. Our results demonstrate a significant function of PgTIP1 in growth and development of plant cells, and suggest that the water movement across tonoplast (via AQP) represents a rate-limiting
factor for plant vigor under favorable growth conditions and also significantly affect responses of plant to drought, salt
and cold stresses. 相似文献
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S. S. Ibragimova Ya. S. Kolodyazhnaya S. V. Gerasimova A. V. Kochetov 《Russian Journal of Plant Physiology》2012,59(1):88-96
The role of gene of proline dehydrogenase (PDH) in the maintenance of stress tolerance was investigated using the model transgenic
plants of tobacco (Nicotiana tabacum L.) carrying an antisense suppressor of PDH gene (a fragment of Arabidopsis PDH gene under the control of cauliflower mosaic virus 35S promoter in antisense orientation) and notable for a low activity
of PDH and elevated content of proline. The progeny of transgenic plants belonging to the 5th generation (T5) with partially suppressed PDH activity was more resistant to various types of stress as compared with the control plants of tobacco, cv. Petit Havana SR-1
(SR1). The seedlings of transgenic lines cultured in Petri dishes on agar media supplemented with stress agents were resistant
to high NaCl concentrations (200–300 mM) and water deficit simulated by an increased agar content in the medium (14 g/l) as
compared to the control seedlings of cv. SR1. Juvenile plants of transgenic lines grown in pots filled with a mixture of vermiculite
and perlite also manifested the higher resistance to water deficit and low temperatures (2°C and −2°C) than the control plants.
Thus, the partial PDH suppression correlated with an increase in nonspecific resistance to different types of abiotic stress: salinity, water deficit,
and low temperatures. Such transgenic lines of tobacco are promising genetic models for thorough investigation of molecular
mechanisms of stress resistance in plants. 相似文献
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Sudip K. Ghosh Nrishingha Dey R. K. Mandal Joydip Dasgupta Indu B. Maiti 《Journal of plant biochemistry and biotechnology.》1994,3(2):141-143
To see the effects of foreign gene introduction on the physiological performance and the quality and quantity of seed lipids, we studied transgenic tobacco plant as a model system, as tobacco seeds are oil seeds. Using Agrobacterium Ti plasmid based vectors, tobacco plants cv Petit Havana were transformed by NPT II gene as selectable marker. Transformed T0 generation plants raised in tissue culture were transferred to pots and selfed. From the seeds, T1 generation plants were grown in pots and their physiological performance was assessed. The transgenic plants showed slightly slower rates of germination and growth. Total chlorophyll content, chlorophyll a/b ratio and specific leaf weight, however, remained unchanged. The transgenic plants also had delayed flowering. However, total protein, lipid content and fatty acid composition of lipids of seeds in transgenic plants did not show appreciable difference from the seeds from control plants. Thus the physiological cost of transgenic plant for the extra genetic load was only marginal, if any. 相似文献
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Tomato plants ectopically expressing Arabidopsis CBF1 show enhanced resistance to water deficit stress 总被引:39,自引:0,他引:39
A DNA cassette containing an Arabidopsis C repeat/dehydration-responsive element binding factor 1 (CBF1) cDNA and a nos terminator, driven by a cauliflower mosaic virus 35S promoter, was transformed into the tomato (Lycopersicon esculentum) genome. These transgenic tomato plants were more resistant to water deficit stress than the wild-type plants. The transgenic plants exhibited growth retardation by showing dwarf phenotype, and the fruit and seed numbers and fresh weight of the transgenic tomato plants were apparently less than those of the wild-type plants. Exogenous gibberellic acid treatment reversed the growth retardation and enhanced growth of transgenic tomato plants, but did not affect the level of water deficit resistance. The stomata of the transgenic CBF1 tomato plants closed more rapidly than the wild type after water deficit treatment with or without gibberellic acid pretreatment. The transgenic tomato plants contained higher levels of Pro than those of the wild-type plants under normal or water deficit conditions. Subtractive hybridization was used to isolate the responsive genes to heterologous CBF1 in transgenic tomato plants and the CAT1 (CATALASE1) was characterized. Catalase activity increased, and hydrogen peroxide concentration decreased in transgenic tomato plants compared with the wild-type plants with or without water deficit stress. These results indicated that the heterologous Arabidopsis CBF1 can confer water deficit resistance in transgenic tomato plants. 相似文献
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Lawrence V. Gusta Nicole T. Benning Guohai Wu Ximing Luo Xunjia Liu Michael L. Gusta Alan McHughen 《Molecular breeding : new strategies in plant improvement》2009,24(2):103-115
The objective of this study was to evaluate the performance of transgenic canola (Brassica napus) plants over-expressing a wheat mitochondrial Mn superoxide dismutase (Mn SOD3.1) subjected to environmental stresses in
the field and in controlled environments. Mn SOD3.1 was regulated by either CaMV 35S or Arabidopsis COR78 promoters. RT-PCR and a SOD enzyme activity assays demonstrated Mn SOD3.1 was expressed at both the mRNA and protein
levels. Enzyme activity assays exhibited total SOD activity was up to 41.8% and up to 26.7% higher in the 35S:SOD3.1 and in
the COR78:SOD3.1 transgenic plants than in the control, respectively. Germination studies, conducted at suboptimal (8°C) and
optimal (23°C) temperatures, identified transgenic lines that germinated earlier than the control. In the field under drought
conditions, several transgenic lines emerged earlier than the control. In both greenhouse and field environments, several
transgenic lines were significantly taller than the control and over 50% of the transgenic canola lines flowered 7–14 days
earlier than the control. Over expression of Mn SOD3.1 enhanced heat, drought and cold tolerance both in the field and under
artificial stress conditions. This is one of the first tests conducted on transgenic canola plants subjected to field conditions. 相似文献
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Effects of early-fruit removal on endogenous cytokinins and abscisic acid in relation to leaf senescence in cotton 总被引:7,自引:0,他引:7
Numerous studies have shown that early-fruit removal enhances vegetative growth and development of cotton (Gossypium hirsutum L.). However, few studies have examined changes in leaf senescence and endogenous hormones due to fruit removal. The objective
of this study was to determine the correlation between some endogenous phytohormones, particularly the cytokinins and abscisic
acid (ABA), and leaf senescence following fruit removal. Cotton was grown in pots and in the field during 2005 and 2006. Two
early-fruiting branches were excised from plants at squaring to form the fruit removal treatment while the non-excised plants
served as control. Plant biomass, seed cotton yield, cytokinins and ABA levels in main-stem leaves and xylem sap as well as
main-stem leaf photosynthetic rate (Pn) and chlorophyll (Chl) concentration were determined after removal or at harvest. Fruit
removals increased the leaf area, root and shoot dry weight and plant biomass at 35 days after removal (DAR), whether in potted
or field-grown cotton; under field conditions, it also improved plant biomass and seed cotton yield at harvest. The Pn and
Chl concentration in excised plants were significantly higher than in control plants from 5 to 35 DAR, suggesting that fruit
removal considerably delayed leaf senescence. Fruit-excised plants contained more trans-zeatin and its riboside (t-Z + t-ZR), dihydrozeatin and its riboside (DHZ + DHZR), and isopentenyladenine and its riboside
(iP + iPA) but less ABA in both main-stem leaves and xylem sap than control plants from 5 to 35 DAR. These results suggest
that removal of early fruiting branches delays main-stem leaf senescence, which can be attributed to increased cytokinin and/or
reduced ABA. Cytokinin and ABA are involved in leaf senescence following early fruit removal. 相似文献
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Hui-Juan Li Ai-Fang Yang Xue-Cheng Zhang Feng Gao Ju-Ren Zhang 《Plant Cell, Tissue and Organ Culture》2007,89(1):37-48
Sucrose: sucrose 1-fructosyltransferase (1-SST) cDNA from Lactuca sativa, coding the enzyme responsible for lower degree polymers fructan biosynthesis, was cloned by RT-PCR and RACE methods. The
1-SST cDNA under the control of CaMV 35S promoter was introduced into tobacco by Agrobacterium-mediated leaf disc transformation protocol. Fructan synthesis in vitro and carbohydrate analysis showed that sense transgenic
tobacco plant displayed sucrose: sucrose 1-fructosyltransferse activity. After freezing stress, significant increases in electrolyte
leakage and malondialdehyde were found in the wild type and anti-sense transgenic plants, while no apparent differences were
observed in sense transgenic plants. Meanwhile, water soluble carbohydrate, fructan and fructose of sense transgenic plants
remarkably increased, compared with those of wild type and anti-sense plants. No significant difference was detected in superoxide
dismutase activity between transgenic and wild type plants. The above results demonstrated that the expression of 1-SST gene improved the freezing resistance of transgenic tobacco plants. 相似文献