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Cryopreservation of Robinia pseudoacacia explants by vitrification achieved 78% survival following the stepwise preculture of shoot tips in (0.3 + 0.5 + 0.7 M) sucrose with a 80 min incubation in PVS2; compared to 87% survival after desiccation of explants to 30% water content, following 3 days alginate bead (with glycerol and sucrose treatments) preculture in 0.7 M sucrose. 相似文献
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An Agrobacterium tumefaciens-based transformation procedure was developed for the desiccation tolerant species Lindernia brevidens. Leaf explants were infected with A. tumefaciens strain GV3101 harbouring a binary vector that carried the hygromycin resistance gene and an eGFP reporter gene under the control of a native dehydration responsive LEA promoter (Lb2745pro). PCR analysis of the selected hygromycin-resistant plants revealed that the transformation rates were high (14/14) and seeds
were obtained from 13/14 of the transgenic lines. A combination of RNA gel blot and microscopic analyses demonstrated that
eGFP expression was induced upon dehydration and ABA treatment. Comparison with existing procedures used to transform the well
studied resurrection plant and close relative, Craterostigma plantagineum, revealed that the transformation process is both rapid and leads to the production of viable seed thus making L. brevidens a candidate species for functional genomics approaches to determine the genetic basis of desiccation tolerance. 相似文献
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N-Acetyltransferase Mpr1 of Saccharomyces cerevisiae can reduce intracellular oxidation levels and protect yeast cells under oxidative stress, including H2O2, heat-shock, or freeze-thaw treatment. Unlike many antioxidant enzyme genes induced in response to oxidative stress, the
MPR1 gene seems to be constitutively expressed in yeast cells. Based on a recent report that ethanol toxicity is correlated with
the production of reactive oxygen species (ROS), we examined here the role of Mpr1 under ethanol stress conditions. The null
mutant of the MPR1 and MPR2 genes showed hypersensitivity to ethanol stress, and the expression of the MPR1 gene conferred stress tolerance. We also found that yeast cells exhibited increased ROS levels during exposure to ethanol
stress, and that Mpr1 protects yeast cells from ethanol stress by reducing intracellular ROS levels. When the MPR1 gene was overexpressed in antioxidant enzyme-deficient mutants, increased resistance to H2O2 or heat shock was observed in cells lacking the CTA1, CTT1, or GPX1 gene encoding catalase A, catalase T, or glutathione peroxidase, respectively. These results suggest that Mpr1 might compensate
the function of enzymes that detoxify H2O2. Hence, Mpr1 has promising potential for the breeding of novel ethanol-tolerant yeast strains. 相似文献
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In mineral salts medium, supplementing with betaine in combination with increased production of endogenous osmoprotectant
from a second copy of the trehalose biosynthetic genes (otsBA) improved growth of E. coli and increased the MIC for xylose, glucose, sodium lactate and NaCl. With these compounds, this combination was more effective
than either betaine or trehalose alone. With succinate, this combination was no more effective than betaine alone. Neither
approach improved tolerance to ethanol. A combination of betaine and increased trehalose may improve strain productivity for
many bioproducts by promoting growth in the presence of high sugar concentrations. 相似文献
7.
We developed an efficient gene transfer method mediated by Agrobacterium tumefaciens for introgression of new rice for Africa (NERICA) cultivars, which are derivatives of interspecific hybrids between Oryza glaberrima Steud. and O. sativa L. Freshly isolated immature embryos were inoculated with A. tumefaciens LBA4404 that harbored binary vector pBIG-ubi::GUS or pIG121Hm, which each carried a hygromycin-resistance gene and a GUS
gene. Growth medium supplemented with 500 mg/l cefotaxime and 20 mg/l hygromycin was suitable for elimination of bacteria
and selection of transformed cells. Shoots regenerated from the selected cells on MS medium containing 20 g/l sucrose, 30 g/l
sorbitol, 2 g/l casamino acids, 0.25 mg/l naphthaleneacetic acid, 2.5 mg/l kinetin, 250 mg/l cefotaxime, and 20 mg/l hygromycin.
The shoots developed roots on hormone-free MS medium containing 30 mg/l hygromycin. Integration and expression of the transgenes
were confirmed by PCR, Southern blot analysis, and histochemical GUS assay. Stable integration, expression, inheritance, and
segregation of the transgenes were demonstrated by molecular and genetic analyses in the T0 and T1 generations. Most plants were normal in morphology and fertile. The transformation protocol produced stable transformants
from 16 NERICA cultivars. We also obtained transformed plants by inoculation of calluses derived from mature seeds, but the
frequency of transformation was lower and sterility was more frequent. 相似文献
8.
Sugar and sugar alcohol concentrations were analyzed in subcellular compartments of mesophyll cells, in the apoplast, and
in the phloem sap of leaves of Plantago major (common plantain), Plantago maritima (sea plantain), Prunus persica (peach) and Apium graveolens (celery). In addition to sucrose, common plantain, sea plantain, and peach also translocated substantial amounts of sorbitol,
whereas celery translocated mannitol as well. Sucrose was always present in vacuole and cytosol of mesophyll cells, whereas
sorbitol and mannitol were found in vacuole, stroma, and cytosol in all cases except for sea plantain. The concentration of
sorbitol, mannitol and sucrose in phloem sap was 2- to 40-fold higher than that in the cytosol of mesophyll cells. Apoplastic
carbohydrate concentrations in all species tested were in the low millimolar range versus high millimolar concentrations in
symplastic compartments. Therefore, the concentration ratios between the apoplast and the phloem were very strong, ranging
between 20- to 100-fold for sorbitol and mannitol, and between 200- and 2000-fold for sucrose. The woody species, peach, showed
the smallest concentration ratios between the cytosol of mesophyll cells and the phloem as well as between the apoplast and
the phloem, suggesting a mixture of apoplastic and symplastic phloem loading, in contrast to the herbal plant species (common
plantain, sea plantain, celery) which likely exhibit an active loading mode for sorbitol and mannitol as well as sucrose from
the apoplast into the phloem. 相似文献
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The N2-fixing cyanobacterium Anabaena sp. PCC7120 showed an inherent capacity for desiccation tolerance. A DNA microarray covering almost the entire genome of Anabaena was used to determine the genome-wide gene expression under desiccation. RNA was extracted from cells at intervals starting from early to late desiccation. The pattern of gene expression in DNA fragments was categorized into seven types, which include four types of up-regulated and three types of down-regulated fragments. Validation of the data was carried out by RT-PCR on selected up-regulated DNA fragments and was consistent with the changes in mRNA levels. Our conclusions regarding desiccation tolerance for Anabaena sp. PCC7120 are as follows: (i) Genes for osmoprotectant metabolisms and the K+ transporting system are up-regulated from early to mid-desiccation; (ii) genes induced by osmotic, salt, and low-temperature stress are up-regulated under desiccation; (iii) genes for heat shock proteins are up-regulated after mid-desiccation; (iv) genes for photosynthesis and the nitrogen-transporting system are down-regulated during early desiccation; and (v) genes for RNA polymerase and ribosomal protein are down-regulated between the early and the middle phase of desiccation. Profiles of gene expression are discussed in relation to desiccation acclimation. 相似文献
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Wang J Raman H Zhou M Ryan PR Delhaize E Hebb DM Coombes N Mendham N 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(2):265-276
Aluminium (Al) tolerance in barley is conditioned by the Alp locus on the long arm of chromosome 4H, which is associated with Al-activated release of citrate from roots. We developed
a high-resolution map of the Alp locus using 132 doubled haploid (DH) lines from a cross between Dayton (Al-tolerant) and Zhepi 2 (Al-sensitive) and 2,070
F2 individuals from a cross between Dayton and Gairdner (Al-sensitive). The Al-activated efflux of citrate from the root apices
of Al-tolerant Dayton was 10-fold greater than from the Al-sensitive parents Zhepi 2 and Gairdner. A suite of markers (ABG715,
Bmag353, GBM1071, GWM165, HvMATE and HvGABP) exhibited complete linkage with the Alp locus in the DH population accounting 72% of the variation for Al tolerance evaluated as relative root elongation. These
markers were used to map this genomic region in the Dayton/Gairdner population in more detail. Flanking markers HvGABP and
ABG715 delineated the Alp locus to a 0.2 cM interval. Since the HvMATE marker was not polymorphic in the Dayton/Gairdner population we instead investigated
the expression of the HvMATE gene. Relative expression of the HvMATE gene was 30-fold greater in Dayton than Gardiner. Furthermore, HvMATE expression in the F2:3 families tested, including all the informative recombinant lines identified between HvGABP and ABG715 was significantly correlated
with Al tolerance and Al-activated citrate efflux. These results identify HvMATE, a gene encoding a multidrug and toxic compound extrusion protein, as a candidate controlling Al tolerance in barley. 相似文献
12.
Lee JH Moon YH Kim N Kim YM Kang HK Jung JY Abada E Kang SS Kim D 《Biotechnology letters》2008,30(4):749-754
The gene encoding sucrose phosphorylase (742sp) in Leuconostoc mesenteroides NRRL B-742 was cloned and expressed in Escherichia coli. The nucleotide sequence of the transformed 742sp comprised an ORF of 1,458 bp giving a protein with calculated molecular mass of 55.3 kDa. 742SPase contains a C-terminal amino acid sequence that is significantly different from those of other Leu. mesenteroides SPases. The purified 742SPase had a specific activity of 1.8 U/mg with a K
m of 3 mM with sucrose as a substrate; optimum activity was at 37°C and pH 6.7. The purified 742SPase transferred the glucosyl
moiety of sucrose to cytosine monophosphate (CMP).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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An efficient gene transfer system without tissue culture steps was developed for kidney bean by using sonication and vacuum
infiltration assisted, Agrobacterium-mediated transformation. Transgenic kidney bean with a group 3 lea (late embryogenesis abundant) protein gene from Brassica napus was produced through this approach. Among 18 combinations of transformation methods, Agrobacterium-mediated transformation combined with 5 min sonication and 5 min vacuum infiltration turned to be optimal, resulting in the
highest transformation efficiency. Transgenic kidney bean plants demonstrated enhanced growth ability under salt and water
deficit stress conditions. The increased tolerance was also reflected by delayed development of damage symptoms caused by
drought stress. Transgenic lines with high level of lea gene expression showed higher stress tolerance than lines with lower expression level. Stress tolerance of transgenic kidney
bean correlated much better with lea gene expression levels than with gene integration results. There is no prior report on the production of transgenic kidney
bean using both ultrasonic and vacuum infiltration assisted, Agrobacterium-mediated transformation. 相似文献
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In Arabidopsis, NPR1 (non-expressor of pathogenesis related genes 1, AtNPR1) functions downstream of salicylic acid (SA) and modulates the SA mediated systemic acquired resistance. It is also involved
in a cross talk with the jasmonate pathway that is essential for resistance against herbivores and necrotrophic pathogens.
Overexpression of AtNPR1 in transgenic plants resulted in enhanced disease resistance. Recently, tobacco transgenic plants expressing AtNPR1 were shown to be tolerant to the early instars of Spodoptera litura (Meur et al., Physiol Plant 133:765–775, 2008). In this communication, we show that the heterologous expression of AtNPR1 in tobacco has also enhanced the oxidative stress tolerance. The transgenic plants exhibited enhanced tolerance to the treatment
with methyl viologen. This tolerance was associated with the constitutive upregulation of PR1, PR2 (glucanase), PR5 (thaumatin like protein), ascorbate peroxidase (APX) and Cu2+/Zn2+ superoxide dismutase (SOD). This is the first demonstration of the novel function of heterologous expression of AtNPR1 in oxidative stress tolerance in transgenic tobacco. 相似文献
16.
T. Zhang 《In vitro cellular & developmental biology. Plant》2007,43(2):91-94
This study investigated the factors affecting in vitro flowering of Perilla frutescens. The shoots regenerated from cotyledonary and hypocotyl explants cultured on Murashige and Skoog (MS) medium supplemented
with benzyladenine (BA) and indole-3-acetic acid, each at 0.5 mg l−1, were excised and transferred to MS medium containing 30 g l−1 of sucrose, 8.25 g l−1 of ammonium nitrate, and 1.0 mg l−1 of BA. After 40 d of culture, 86.2% of shoots flowered and most of which self-fertilized in vitro and produced mature fruits with viable seeds. These seeds were germinated and plants were grown to maturity and flowered
in soil under greenhouse conditions. The in vitro flowering system reported in this study may facilitate rapid breeding of P. frutescens and offers a model system for studying the physiological mechanism of flowering. 相似文献
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Staphylococcus aureus is a multidrug-resistant pathogen that not only causes a diverse array of human diseases, but also is able to survive in
potentially dry and stressful environments, such as the human nose, on skin and on inanimate surfaces such as clothing and
surfaces. This study investigated parameters governing desiccation tolerance of S. aureus and identified several components involved in the process. Initially, the role of environmental parameters such as temperature,
growth phase, cell density, desiccation time and protectants in desiccation tolerance were determined. This established a
robust model of desiccation tolerance in which S. aureus has the ability to survive on dry plastic surfaces for more than 1,097 days. Using a combination of a random screen and defined
mutants, clpX, sigB and yjbH were identified as being required for desiccation tolerance. ClpX is a part of the ATP-dependent ClpXP protease, important for protein turnover, and YjbH has a proposed linked function.
SigB is an accessory sigma factor with a role in generalized stress resistance. Understanding the molecular mechanisms that
govern desiccation tolerance may determine the break points to be exploited to prevent the spread of this dangerous pathogen
in hospitals and communities. 相似文献
18.
Takashi Okada Andrew S. Catanach Susan D. Johnson Ross A. Bicknell Anna M. Koltunow 《Sexual plant reproduction》2007,20(4):199-211
Asexual seed formation (apomixis) in Hieracium aurantiacum occurs by mitotic embryo sac formation without prior meiosis in ovules (apomeiosis), followed by fertilization-independent
embryo and endosperm development. Sexual reproduction begins first in Hieracium ovules with megaspore mother cell (MMC) formation. Apomixis initiates with the enlargement of somatic cells, termed aposporous
initial (AI) cells, near sexual cells. AI cells grow towards sexually programmed cells undergoing meiosis, which degrade as
the dividing nuclei of AIs obscure and displace them. Following Agrobacterium-mediated transformation of an aneuploid Hieracium aurantiacum apomict, a somaclonal mutant designated “loss of apomeiosis 1” (loa1) was recovered, which had significantly lost the ability to form apomictic seed. Maternal apomictic progeny were rare and
low levels of germinable seedlings were primarily derived from meiotically derived eggs. Cytological analysis revealed defects
in AI formation and function in loa1. Somatic cells enlarged some distance away from sexual cells and unlike AI cells, these expanded away from sexual cells without
nuclear division. Surprisingly, many accumulated callose in the walls, a marker associated with meiotically specified cells.
These defective AI (DAI) cells only had partial sexual identity as they failed to express a marker reflecting entry to meiosis
that was easily detected in MMCs and they ultimately degraded. DAI cell formation did not lead to a compensatory increase
in functional sexual embryo sacs, as collapse of meiotic embryo sacs was prevalent in the aneuploid somaclonal mutant. Positional
cues that are important for AI cell differentiation, growth and fate may have been disrupted in the loa1 mutant and this is discussed.
The authors Takashi Okada, Andrew S. Catanach and Susan D. Johnson made equal contributions to the data. 相似文献
19.
Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification
generates synthesis gas consisting primarily of CO, CO2, H2, N2, with smaller amounts of CH4, NOx, O2, C2 compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents.
However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to
enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation.
Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels
of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing
cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios. 相似文献
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Konstantin V. Kiselev Anna V. Turlenko Yuri N. Zhuravlev 《Plant Cell, Tissue and Organ Culture》2009,99(2):141-149
A somatic embryogenesis protocol for plant regeneration of northern red oak (Quercus rubra) was established from immature cotyledon explants. Embryogenic callus cultures were induced on Murashige and Skoog medium
(MS) containing 3% sucrose, 0.24% Phytagel™, and various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d) after 4 weeks of culture in darkness. A higher response (66%) of embryogenic callus was induced on 0.45 μM 2,4-d. Higher numbers of globular- (31), heart- (17), torpedo- (12), and cotyledon-stage (8) embryos per explant were obtained
by culturing embryogenic callus on MS with 3% sucrose, 0.24% Phytagel™, and devoid of growth regulators after 8 weeks culture
in darkness. Continuous sub-culturing of embryogenic callus on medium containing 2,4-d yielded only compact callus. Desiccation of embryos for 3 days in darkness at 25 ± 2°C followed by cold storage at 4°C in
darkness for 8 weeks favored embryo germination and development of plantlets. Cotyledon-stage embryos subjected to desiccation
and chilling treatment cultured on MS with 3% sucrose, 0.24 Phytagel™, 0.44 μM 6-benzylaminopurine (BA), and 0.29 μM gibberellic
acid germinated at a higher frequency (61%) than with 0.44 μM BA alone and control cultures. Germinated plantlets developed
a shoot and root, were acclimatized successfully, and maintained in a growth room for plantlet development. 相似文献