Relationship between Starch Accumulation and Activities of the Related Enzymes in the Leaf Sheath as a Temporary Sink Organ in Rice (Oryza sativa)

The starch stored temporarily in the leaf sheath of rice plants is translocated to the grain, contributing to the grain yield. In this paper, the relationship between starch accumulation and the activities of enzymes involved in the starch biosynthetic pathway in the leaf sheaths of rice plants was examined to elucidate the regulation mechanism of starch accumulation in the temporary sink organ. When the starch content was compared between different leaf sheath positions on the main stem, the 14th leaf sheath counted from the bottom, which elongated just before anthesis, showed about a four-fold higher value than the 10th leaf sheath. Among the enzymes involved in carbohydrate metabolism, the activity of starch branching enzyme (BE, EC2.4.1.18) was greatly higher in the 14th leaf sheath than in the 10th leaf sheath, while that of ADPglucose pyrophosphorylase (EC2.7.7.27) was similar between the two leaf sheaths. The starch content increased rapidly in the period around anthesis in the 12th and 14th leaf sheaths, but did not in the 10th and 11th leaf sheath. In the higher leaf sheath position, the activity of BE changed with noticeably similar trend to the starch content. Soluble starch synthase (SSS, EC2.4.1.21), granule-bound starch synthase (GBSS, EC2.4.1.21) and plastidial fructose- 1,6-bisphosphatase (FBPase, EC3.1.3.11) were also significantly correlated with the starch content. These results suggest that BE is involved in regulation of starch metabolism, possibly in collaboration with other enzymes such as SSS, GBSS and plastidial FBPase in temporary sink organs like the leaf sheath.

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EVALUACIÓN DE LA EXPRESIÓN DE GENES IMPLICADOS EN LA BIOSÍNTESIS DE ALMIDÓN EN DIFERENTES VARIEDADES DE YUCA

Acta Biológica Colombiana ◽

10.15446/abc.v20n2.42875 ◽

2014 ◽

Vol 20 (2) ◽

Author(s):

Simón Pedro Cortés Sierra ◽

Paul Chavarriaga ◽

Hernán Ceballos ◽

Camilo Ernesto López Carrascal

Keyword(s):

Gene Expression ◽

Soluble Starch ◽

Matter Content ◽

Starch Synthase ◽

Starch Accumulation ◽

Dry Matter Content ◽

Storage Roots ◽

Expression Levels ◽

Study Gene Expression ◽

Cassava Varieties

Las raíces almacenadoras de yuca representan una fuente importante de almidón. La ruta metabólica del almidón ha sido reconstruida recientemente en yuca gracias a la liberación de la secuencia completa de su genoma. En este estudio se evaluó la expresión de los genes que codifican para las enzimas Pululanasa, Isoamilasa, α-amilasa, Enzima Desproporcionante, ADP-glucosa pirofoforilasa, Almidón sintasa unida al gránulo, Enzima ramificante del almidón y Sintasa soluble del almidón, en las raíces almacenadoras de plantas de 5 y 11 meses de edad, en un grupo de cinco variedades de yuca. Se evidenciaron diferencias importantes en la expresión de estos genes entre las variedades evaluadas y entre los dos tiempos. Las variedades CM523-7 y SM1219-2 presentaron uno de los niveles más altos de expresión para los genes ADP-glucosa pirofoforilasa y Almidón sintasa unida al gránulo mientras que el gen para α-amilasa fue el más bajo en estas dos variedades. Aunque la variedad TMS60444 presentó niveles de expresión similares en genes implicados en la síntesis de almidón, fue la que presentó el mayor nivel de expresión de la α-amilasa. Estos datos se pueden correlacionar con el relativo bajo contenido de materia seca en esta variedad. Los datos de expresión génica presentados en este trabajo permitirán complementar información sobre actividad enzimática con miras a identificar los elementos más importantes en la acumulación diferencial de almidón entre variedades de yuca.ABSTRACTCassava storage roots represent an important starch source. Recently, the starch metabolic pathway in cassava has been reconstructed thanks to the full release of its genome. In this study gene expression was evaluated for genes coding Pullulanase, Isoamylase, α-amylase, Deproportionating enzyme, ADP-glucose pyrophosphorylase, Granule bound starch synthase, Starch branching enzyme and Soluble starch synthase, in cassava storage roots 5 and 11 months old, in 5 cassava varieties. Important gene expression differences were detected both at the variety and time level. CM523-7 and SM1219-2 showed one of the highest expression levels for AGPase and GBSS genes, while α-amylase showed the lowest level in these two varieties. TMS60444 variety showed similar expression levels in starch biosynthesis-related genes, but conversely also showed the highest α-amylase expression. This correlates with the relative low dry-matter content in TMS60444. Gene expression data reported here will allow complementing actual information on enzymatic activity, in order to identify the most relevant factors in differential starch accumulation between cassava varieties.

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The Effect of High Temperature on Starch Synthesis and the Activity of Starch Synthase

Functional Plant Biology ◽

10.1071/pp9940783 ◽

1994 ◽

Vol 21 (6) ◽

pp. 783 ◽

Cited By ~ 33

Author(s):

K Denyer ◽

CM Hylton ◽

AM Smith

Keyword(s):

High Temperature ◽

Starch Content ◽

Starch Synthesis ◽

Soluble Starch ◽

Maximum Activity ◽

Starch Synthase ◽

Heat Inactivation ◽

Heat Sensitivity ◽

Potato Tubers ◽

Storage Organs

The decrease in yield which is observed when developing storage organs such as cereal grains or potato tubers are exposed to high temperatures is due to a lower final starch content. The rate of starch synthesis during the development of these storage organs at high temperature, is either reduced or fails to increase sufficiently to compensate for the shorter developmental period. This effect on the rate of starch synthesis does not seem to be due to a reduction in the supply of photosynthate. One of the enzymes in the pathway of starch synthesis, soluble starch synthase, is susceptible to heat inactivation at unusually low temperatures and may also have a low optimum temperature for maximum activity. In some storage organs, the maximum catalytic activity of soluble starch synthase is not very much greater than the rate of starch synthesis. A decrease in the activity of this enzyme is therefore, likely to affect the rate of starch synthesis. Thus, the effect of high temperature on the rate of starch synthesis may be due, at least in part, to the properties of this enzyme. This review discusses the unusual heat-sensitivity of starch synthase in the context ofthe effects of high temperature on starch synthesis in storage organs.

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Microbial Volatile-Induced Accumulation of Exceptionally High Levels of Starch in Arabidopsis Leaves Is a Process Involving NTRC and Starch Synthase Classes III and IV

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-05-11-0112 ◽

2011 ◽

Vol 24 (10) ◽

pp. 1165-1178 ◽

Cited By ~ 25

Author(s):

Jun Li ◽

Ignacio Ezquer ◽

Abdellatif Bahaji ◽

Manuel Montero ◽

Miroslav Ovecka ◽

...

Keyword(s):

Time Course ◽

Starch Content ◽

Thioredoxin Reductase ◽

Redox Status ◽

Starch Synthase ◽

Reduced Form ◽

Starch Accumulation ◽

Knockout Mutants ◽

Microbial Volatiles ◽

The Impact

Microbial volatiles promote the accumulation of exceptionally high levels of starch in leaves. Time-course analyses of starch accumulation in Arabidopsis leaves exposed to fungal volatiles (FV) emitted by Alternaria alternata revealed that a microbial volatile-induced starch accumulation process (MIVOISAP) is due to stimulation of starch biosynthesis during illumination. The increase of starch content in illuminated leaves of FV-treated hy1/cry1, hy1/cry2, and hy1/cry1/cry2 Arabidopsis mutants was many-fold lower than that of wild-type (WT) leaves, indicating that MIVOISAP is subjected to photoreceptor-mediated control. This phenomenon was inhibited by cordycepin and accompanied by drastic changes in the Arabidopsis transcriptome. MIVOISAP was also accompanied by enhancement of the total 3-phosphoglycerate/Pi ratio, and a two- to threefold increase of the levels of the reduced form of ADP-glucose pyrophosphorylase. Using different Arabidopsis knockout mutants, we investigated the impact in MIVOISAP of downregulation of genes directly or indirectly related to starch metabolism. These analyses revealed that the magnitude of the FV-induced starch accumulation was low in mutants impaired in starch synthase (SS) classes III and IV and plastidial NADP-thioredoxin reductase C (NTRC). Thus, the overall data showed that Arabidopsis MIVOISAP involves a photocontrolled, transcriptionally and post-translationally regulated network wherein photoreceptor-, SSIII-, SSIV-, and NTRC-mediated changes in redox status of plastidial enzymes play important roles.

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Sink strength in relation to growth of superior and inferior grains within a wheat spike

The Journal of Agricultural Science ◽

10.1017/s0021859610000407 ◽

2010 ◽

Vol 148 (5) ◽

pp. 567-578 ◽

Cited By ~ 6

Author(s):

S. YAN ◽

W. LI ◽

Y. YIN ◽

Z. WANG

Keyword(s):

Accumulation Rate ◽

Soluble Starch ◽

Cell Number ◽

Starch Synthase ◽

Grain Weight ◽

Starch Accumulation ◽

Sink Strength ◽

Endosperm Cell ◽

Compact Spike ◽

Wheat Spike

SUMMARYStarch is a major component of wheat grain and, to a great extent, determines the grain weight. Starch accumulation in wheat (Triticum aestivum L.) is closely associated with sink strength. Four winter wheat cultivars, Lumai 21 and Jimai 20 (compact-spike cultivars) and Shannong 1391 and Shannong 12 (loose-spike cultivars) were grown to evaluate the amylose and amylopectin accumulation in both superior and inferior grains (higher and lower individual grain weight, respectively) and the relationship between starch accumulation and sink strength. In general, superior grains showed a higher starch accumulation rate, endosperm cell number and activity of enzymes including sucrose synthase (SS), uridine diphosphorate glucose pyrophosphorylase (UGPP), adenosine diphosphorate glucose pyrophosphorylase (AGPP), soluble starch synthase (SSS) and granule-bound starch synthase (GBSS), and subsequently produced higher starch accumulation and grain weight than inferior grains. Greater differences in starch accumulation and grain weight were found between the two classes of grains for compact-spike cultivars than between those for loose-spike cultivars. These results suggest that the grain sink strength, determined by endosperm cell number and the activity of synthesis-related enzymes, is closely associated with starch accumulation in superior and inferior grains on a wheat spike.

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Starch synthesis and localization in post-germination Pinusedulis seedlings

Canadian Journal of Forest Research ◽

10.1139/x94-188 ◽

1994 ◽

Vol 24 (7) ◽

pp. 1457-1463 ◽

Cited By ~ 6

Author(s):

J. Brad Murphy ◽

Mark F. Hammer

Keyword(s):

Seed Germination ◽

Starch Content ◽

Starch Synthesis ◽

Minor Component ◽

Dry Weight ◽

Starch Synthase ◽

Starch Accumulation ◽

Low Levels ◽

Starch Conversion ◽

A Minor

Following pine seed germination, lipids in the megagametophyte are converted to sucrose, which is transported to the emerging seedling to support its growth. In several conifer species, an increase in the seedling starch content following germination has been reported. To further characterize this phenomenon, starch accumulation and localization, starch synthase (EC 2.4.1.21) activity (both soluble and granule-bound), and partitioning of exogenous 14C-sucrose were determined following germination of pinyon (Pinusedulis Engelm.) seeds. Starch was a minor component in dry embryos, accounting for only 3% of the dry weight. Starch levels increased 22-fold and 15-fold in the cotyledons and hypocotyl, respectively, by 8 days after germination. Starch accumulated to 65% of the dry weight in the cotyledons and 46% in the hypocotyl. The root and epicotyl accumulated relatively low levels of starch, only about 7%. Starch was localized primarily in the cortex and pith of the hypocotyl, the cortex of the cotyledons, and the root cap. Only granule-bound starch synthase showed a significant increase in activity during germination, and its changes more closely followed the pattern of starch accumulation. Exogenous 14C-sucrose was partitioned primarily into starch. After a 24-h labeling period, starch in both the cotyledons and hypocotyl accounted for 38% of total label (61% of the incorporated label) in these organs. In the roots, starch accounted for only 2.5 and 14%, respectively, of the total and incorporated label. The spatial and temporal pattern of starch accumulation closely paralleled previously reported patterns for the activity of sucrose synthase, which is apparently associated with the sucrose–starch conversion. Starch accumulation in the seedling accounts for approximately 50% of the sucrose transported from the megagametophyte following pinyon seed germination. Thus, starch appears to serve as an important transitory carbon pool for the growing seedling and may serve additional functions during seedling development.

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Effects of low temperature on grain filling, amylose content, and activity of starch biosynthesis enzymes in endosperm of basmati rice

Australian Journal of Agricultural Research ◽

10.1071/ar07340 ◽

2008 ◽

Vol 59 (7) ◽

pp. 599 ◽

Cited By ~ 19

Author(s):

Nisar Ahmed ◽

Masahiko Maekawa ◽

Ian J. Tetlow

Keyword(s):

Low Temperature ◽

Amylose Content ◽

Oryza Sativa L ◽

Starch Content ◽

Grain Filling ◽

Soluble Starch ◽

Starch Biosynthesis ◽

Starch Synthase ◽

Basmati Rice ◽

Starch Phosphorylase

The effects of low temperature on amylose contents and activities of key enzymes related to starch biosynthesis in basmati rice (Oryza sativa L.) endosperm were investigated. Low temperature treatment prolonged the grain-filling period from 32 days to 53 days, but had no significant effect on the final grain weight. Results showed that low temperature during grain filling had no significant effect on total starch content but increased the amylose content in the mature endosperm of hulled rice by 21%. The measurable activities of sucrose synthase (SuSy), ADP-glucose pyrophosphorylase (AGPase), starch phosphorylase (SPase), starch branching enzyme (SBE), and soluble starch synthase (SS) in endosperms developed at 12°C were lower than those at 22°C when compared at a similar ripening stage on an endosperm basis, but the activity of granule-bound starch synthase (GBSS) was significantly higher than the corresponding activity in endosperms developing at 22°C. These findings suggest that GBSS might play a crucial role in increasing amylose during low-temperature growth conditions.

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

Vietnam Journal of Biotechnology ◽

10.15625/1811-4989/14/2/9354 ◽

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.

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