Expression of a yeast-derived invertase in companion cells results in long-distance transport of a trisaccharide in an apoplastic loader and influences sucrose transport

Zuther, Ellen; Kwart, Marion; Willmitzer, Lothar; Heyer, Arnd G.

doi:10.1007/s00425-003-1148-7

Cited by 28 publications

(22 citation statements)

References 38 publications

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“…2X35S::AI-1) suggest that modest levels of heterologous invertase expression may be suYcient to alter the WT phenotype. These Wndings are not unique to this study as signiWcant diVerences in invertase activity were not detected in leaf mid ribs of Solanum tuberosum between a line expressing CI under the control of a companion cell-speciWc promoter (rolC invertase 3) and WT plants (Zuther et al 2004). Thus, it is plausible that the tissue-speciWc 4CL promoter and the 2X35S promoter lead to levels of heterologous invertase activity that are diYcult to detect above background activity of native invertase, yet allow suYcient expression to generate phenotypes that diVer from WT tobacco.…”

Section: Discussionmentioning

confidence: 76%

Varied growth, biomass and cellulose content in tobacco expressing yeast-derived invertases

Canam

Park

et al. 2006

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The effects of the expression of yeast-derived apoplastic (AI) and cytosolic (CI) invertases (EC 3.2.1.26) on biomass and structural carbohydrate accumulation in tobacco (Nicotiana tabacum L. cv. Xanthi) were evaluated. Transgenic tobacco plants expressing AI or CI under the control of either a tandem repeat of the Cauliflower Mosaic Virus 35S promoter (2X35S), or a promoter that drives xylem-localized expression (Petroselinum crispum 4-coumarate:CoA ligase promoter; 4CL) were generated. Yeast-derived invertase transcript levels, invertase protein, enzyme activity, growth parameters as well as both structural and soluble carbohydrates of stem tissue of all transformed lines were quantified. Transgenic tobacco lines expressing invertase under the control of 4CL displayed severe growth retardation with both yeast-derived isogenes. Similarly, several transformed lines expressing either AI or CI regulated by the 2X35S promoter were also shorter than wild-type (WT) plants. Despite the decreases in height, some transformed lines had significant increases in biomass. One line (2X35S::AI-1) had a biomass/height increase of 88% and an increase in stem diameter of over 40%, while a second line (2X35S::CI-5) had a biomass/height increase of 21%. A separate line (2X35S::AI-2) had a 36% increase in cellulose content, while two others (4CL::AI-2 and 4CL::AI-3) displayed significant decreases in cellulose content. The observed phenotypes can be in part explained by the levels of foreign invertase present, subcellular localization and the carbohydrate status of the tissues.

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Section: Discussionmentioning

confidence: 76%

Varied growth, biomass and cellulose content in tobacco expressing yeast-derived invertases

Canam

Park

et al. 2006

Planta

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“…It has been reported that overexpression of yeast invertase in the companion cell cytosol of potato results in the synthesis and transport of a novel trisaccharide, 6-kestose (Zuther et al, 2004). To test whether overexpression of cell wall invertase modifies the transport sugars in poplar, we analyzed sugars extracted from the petioles of leaves exposed to 14 CO 2 .…”

Section: Discussionmentioning

confidence: 99%

Symplastic Phloem Loading in Poplar

et al. 2014

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Sap is driven through phloem sieve tubes by an osmotically generated pressure gradient between source and sink tissues. In many plants, source pressure results from thermodynamically active loading in which energy is used to transfer sucrose (Suc) from mesophyll cells to the phloem of leaf minor veins against a concentration gradient. However, in some species, almost all trees, correlative evidence suggests that sugar migrates passively through plasmodesmata from mesophyll cells into the sieve elements. The possibility of alternate loading mechanisms has important ramifications for the regulation of phloem transport and source-sink interactions. Here, we provide experimental evidence that, in gray poplar (Populus tremula 3 Populus alba), Suc enters the phloem through plasmodesmata. Transgenic plants were generated with yeast invertase in the cell walls to prevent Suc loading by this route. The constructs were driven either by the constitutive 35S promoter or the minor vein-specific galactinol synthase promoter. Transgenic plants grew at the same rate as the wild type without symptoms of loading inhibition, such as accumulation of carbohydrates or leaf chlorosis. Rates of photosynthesis were normal. In contrast, alfalfa (Medicago sativa) plants, which have limited numbers of plasmodesmata between mesophyll and phloem, displayed typical symptoms of loading inhibition when transformed with the same DNA constructs. The results are consistent with passive loading of Suc through plasmodesmata in poplar. We also noted defense-related symptoms in leaves of transgenic poplar when the plants were abruptly exposed to excessively high temperatures, adding to evidence that hexose is involved in triggering the hypersensitive response.

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“…We are also grateful to Prof. Mark Tester, Australian Centre for Plant Functional Genomics, University of Adelaide, Australia, for discussing hydroponic growth of barley plants. Special thanks to Dr. Ellen Zuther, Max-Planck-Institute for Plant Molecular Physiology, Golm, Germany, for providing us with purified 6 kestose (Zuther et al, 2004) for peak identification. U.R.…”

Section: Acknowledgmentsmentioning

confidence: 99%

An Investigation of Boron Toxicity in Barley Using Metabolomics

et al. 2006

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Boron (B) is an essential micronutrient that affects plant growth at either deficient or toxic concentrations in soil. The aim of this work was to investigate the adaptation of barley (Hordeum vulgare) plants to toxic B levels and to increase our understanding of B toxicity tolerance mechanisms. We used a metabolomics approach to compare metabolite profiles in root and leaf tissues of an intolerant, commercial cultivar (cv Clipper) and a B-tolerant Algerian landrace (cv Sahara). After exposure to elevated B (200 and 1,000 mM), the number and amplitude of metabolite changes in roots was greater in Clipper than in Sahara. In contrast, leaf metabolites of both cultivars only responded following 1,000 mM treatment, at which B toxicity symptoms (necrosis) were visible. In addition, metabolite levels were dramatically altered in the tips of leaves of the sensitive cultivar Clipper after growth in 1,000 mM B compared to those of Sahara. This correlates with a gradual accumulation of B from leaf base to tip in B-intolerant cultivars. Overall, there were always greater differences between tissue types (roots and leaves) than between the two cultivars. This work has provided insights into metabolic differences of two genetically distinct barley cultivars and information about how they respond metabolically to increasing B levels.Boron (B) is an essential micronutrient for vascular plants. However, when B is present at high concentrations in the soil or ground water, plant growth and reproduction can be affected by B toxicity. B toxicity has been recognized as an important problem limiting crop production in the low rainfall and on highly alkaline and saline soils in regions of Australia, West Asia, and North Africa. Because soil amelioration is impractical, the development of B-tolerant cultivars is a rational solution to the problem.B freely diffuses into the roots as boric acid [B(OH) 3 ; pK a 5 9.25] and accumulates in the cytoplasm as the borate anion [B(OH) 4 2 ] due to pH-dependent interconversion. An inability to exclude B from the roots results in high B concentrations in the tissue. B phytotoxicity manifests itself in a broad range of physiological effects, including decreased shoot and root growth, root cell division and RNA content, reduced leaf chlorophyll, lower photosynthetic rates and stomatal conductance, and reduced levels of lignin and suberin (for review, see Nable et al., 1997). Leaf symptoms of toxicity in barley (Hordeum vulgare) are characterized by interveinal chlorotic and/or necrotic patches, generally at the margins and tips of older leaves. This reflects the accumulation of B at the end of the transpiration stream (Nable et al., 1997). Following long-term exposure to high B concentrations in the soil, overall vegetative plant growth is retarded and this leads to either a reduction in or a complete lack of seed set.B is also an essential nutrient, although its role in plant growth, development, and metabolism remains to be clarified. Originally, B was thought to be essentially immobile in the ...

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Expression of a yeast-derived invertase in companion cells results in long-distance transport of a trisaccharide in an apoplastic loader and influences sucrose transport

Cited by 28 publications

References 38 publications

Varied growth, biomass and cellulose content in tobacco expressing yeast-derived invertases

Varied growth, biomass and cellulose content in tobacco expressing yeast-derived invertases

Symplastic Phloem Loading in Poplar

An Investigation of Boron Toxicity in Barley Using Metabolomics

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