scholarly journals Overexpression of plastidial thioredoxin f leads to enhanced starch accumulation in tobacco leaves

2013 ◽  
Vol 11 (5) ◽  
pp. 618-627 ◽  
Author(s):  
Ruth Sanz-Barrio ◽  
Patricia Corral-Martinez ◽  
Maria Ancin ◽  
Jose M. Segui-Simarro ◽  
Inmaculada Farran
Keyword(s):  
Starch Accumulation ◽  
Tobacco Leaves ◽  
Thioredoxin F

scholarly journals Shifting carbon flux from non-transient starch to lipid allows oil accumulation in transgenic tobacco leaves

2020 ◽  
Author(s):  
Kevin L. Chu ◽  
Lauren M. Jenkins ◽  
Sally R. Bailey ◽  
Shrikaar Kambhampati ◽  
Somnath Koley ◽  
...  
Keyword(s):  
Transgenic Tobacco ◽  
Carbon Flux ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Starch Accumulation ◽  
Leaf Biomass ◽  
Wild Type ◽  
Oil Accumulation ◽  
Tobacco Leaves ◽  
Source Sink

AbstractPlant leaf biomass is composed predominantly of carbohydrate and protein with less than 5% dry weight allocated to lipid and less than 1% of total lipid in the form of triacylglycerols (TAGs). The combined overexpression of multiple genes involved in different aspects of TAG synthesis and stabilization can result in TAG accumulation to over 30% dry weight in tobacco leaves, presumably requiring many metabolic adjustments within plant cells. The metabolic consequences to the combined source and sink capacities of high oil accumulating transgenic tobacco leaves compared to wild-type were inspected across development and photoperiod by utilizing foliar biomass components and 13CO2 flux through central carbon intermediates. Lipid biosynthesis was investigated through assessment of acyl-acyl carrier protein (ACP) pools using a recently derived quantification method that was extended to accommodate isotopic labeling. Lipids accumulated stepwise over plant development in the high-oil leaves, with 13CO2-labeling studies confirming increased carbon flux to lipids. The large increase in lipid content was concurrent with a decrease in foliar starch, with limited contribution from non-sucrose soluble sugars, indicating a redirection of carbon from starch to lipids. Starch accumulated non-transiently with plant age in wild-type leaves, suggesting an inherent capacity for a developmentally-regulated carbon sink in tobacco leaves that may have enabled the programmed altered carbon partitioning to lipids in transgenics. These studies provide insight into the metabolic plasticity of dual source-sink leaves over development and may in part explain recent successful leaf lipid engineering efforts in tobacco.One sentence summaryEngineering high oil accumulation in tobacco leaves is enabled by inherent source-sink plasticity associated with non-transient foliar starch accumulation over development.

scholarly journals NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves

Plants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 543 ◽  
Author(s):  
María Ancín ◽  
Luis Larraya ◽  
Alicia Fernández-San Millán ◽  
Jon Veramendi ◽  
Tessa Burch-Smith ◽  
...  
Keyword(s):  
Starch Content ◽  
Starch Synthesis ◽  
Genetically Engineered ◽  
Starch Accumulation ◽  
Starch Metabolism ◽  
Reductive Activation ◽  
Amylolytic Enzyme ◽  
Tobacco Plants ◽  
Tobacco Leaves ◽  
The Impact

Thioredoxin (Trx) f and NADPH-dependent Trx reductase C (NTRC) have both been proposed as major redox regulators of starch metabolism in chloroplasts. However, little is known regarding the specific role of each protein in this complex mechanism. To shed light on this point, tobacco plants that were genetically engineered to overexpress the NTRC protein from the chloroplast genome were obtained and compared to previously generated Trx f-overexpressing transplastomic plants. Likewise, we investigated the impact of NTRC and Trx f deficiency on starch metabolism by generating Nicotiana benthamiana plants that were silenced for each gene. Our results demonstrated that NTRC overexpression induced enhanced starch accumulation in tobacco leaves, as occurred with Trx f. However, only Trx f silencing leads to a significant decrease in the leaf starch content. Quantitative analysis of enzyme activities related to starch synthesis and degradation were determined in all of the genotypes. Zymographic analyses were additionally performed to compare the amylolytic enzyme profiles of both transplastomic tobacco plants. Our findings indicated that NTRC overexpression promotes the accumulation of transitory leaf starch as a consequence of a diminished starch turnover during the dark period, which seems to be related to a significant reductive activation of ADP-glucose pyrophosphorylase and/or a deactivation of a putative debranching enzyme. On the other hand, increased starch content in Trx f-overexpressing plants was connected to an increase in the capacity of soluble starch synthases during the light period. Taken together, these results suggest that NTRC and the ferredoxin/Trx system play distinct roles in starch turnover.

The maize plastidic thioredoxin F-type gene ZmTrxF increases starch accumulation in transgenic Arabidopsis

2016 ◽  
Vol 210 ◽  
pp. 205-212 ◽  
Author(s):  
Feibing Wang ◽  
Xiaotong Guo ◽  
Xuqiang Qiao ◽  
Juan Zhang ◽  
Chunyan Yu ◽  
...  
Keyword(s):  
Transgenic Arabidopsis ◽  
Starch Accumulation ◽  
Type Gene ◽  
Thioredoxin F

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Co-expression of AGPS and AGPL genes encoded for AGPase from cassava to enhance starch accumulation in transgenic tobacco

2016 ◽  
Vol 14 (2) ◽  
pp. 287-293
Author(s):  
Nguyễn Văn Đoài ◽  
Nguyễn Minh Hồng ◽  
Lê Thu Ngọc ◽  
Nguyễn Thị Thơm ◽  
Nguyễn Đình Trọng ◽  
...  
Keyword(s):  
Transgenic Tobacco ◽  
Higher Plants ◽  
Starch Content ◽  
Genetically Modified Crops ◽  
Starch Accumulation ◽  
35S Promoter ◽  
Effective Strategies ◽  
Plant Expression Vector ◽  
Transgenic Lines ◽  
Cassava Varieties

The AGPase (ADP-Glucose pyrophosphorylase) is one of the ubiquitous enzymes catalyzing the first step in starch biosynthesis. It plays an important role in regulation and adjusts the speed of the entire cycle of glycogen biosynthesis in bacteria and starch in plants. In higher plants, it is a heterotetramer and tetrameric enzyme consisting two large subunits (AGPL) and two small subunits (AGPS) and encoded by two genes. In this paper, both AGPS and AGPL genes were sucessfully isolated from cassava varieties KM140 and deposited in Genbank with accession numbers KU243124 (AGPS) and KU243122 (AGPL), these two genes were fused with P2a and inserted into plant expression vector pBI121 under the control of 35S promoter. The efficient of this construct was tested in transgenic N. tabacum. The presence and expression of AGPS and AGPL in transgenic plants were confirmed by PCR and Western hybridization. The starch content was quantified by the Anthrone method. Transgenic plant analysis indicated that that two targeted genes were expressed simultaneously in several transgenic tobacco lines under the control of CaMV 35S promoter.  The starch contents in 4 analyzed tobacco transgenic lines displays the increase 13-116%  compared to WT plants. These results indicated that the co-expression of AGPS and AGPL is one of effective strategies for enhanced starch production in plant. These results can provide a foundation for developing other genetically modified crops to increase starch accumulation capacity.

Varietal difference of root development and starch accumulation on stem of tomato occurred by fruit thinning

Root Research ◽  
2012 ◽  
Vol 21 (2) ◽  
pp. 39-43 ◽  
Author(s):  
Akimasa Nakano ◽  
Ryo Matsuda ◽  
Masahumi Johkan ◽  
Katsumi Suzuki ◽  
Donghyuk Ahn ◽  
...  
Keyword(s):  
Root Development ◽  
Varietal Difference ◽  
Starch Accumulation ◽  
Fruit Thinning
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