Assimilate Partitioning Within Floret Components of Contrasting Rice Spikelets Producing Qualitatively Different Types of Grains

1996 ◽  
Vol 23 (1) ◽  
pp. 85 ◽  
Author(s):  
R Patel ◽  
PK Mohapatra
Keyword(s):  
Sucrose Synthase ◽  
Grain Quality ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Poor Quality ◽  
Primary Branch ◽  
Assimilate Partitioning ◽  
Different Types ◽  
Carbohydrate Contents ◽  
Rice Panicles

Grain quality, soluble and insoluble carbohydrate contents, and activities of two key enzymes (sucrose synthase and invertase) involved in starch synthesis in the endosperm were measured in the components of the fertile florets of spikelets located at the tip of the uppermost primary branch (top spikelet), and the penultimate position of the lowermost primary branch (basal spikelet) of rice panicles during the period begining some days before anthesis to maturity. The basal spikelet, which reached anthesis a week after the top spikelet, produced a partially filled poor quality grain in contrast to the good quality high density grain produced by the latter. Sucrose was the major translocatable sugar in the organs of the fertile florets of both top and basal spikelets, and poor grain filling of the latter was not caused by deficiency of this material due to any resistance in supply in the external protective organs. The activities of the sucrose synthase and invertase were higher and lower respectively, in the endosperm cells of the top spikelet compared with the basal spikelet. We conclude that poor synthesis of the starch leading to partial grain filling in the basal spikelet is due to a lower activity of sucrose synthase.

Ethylene inhibitors enhanced sucrose synthase activity and promoted grain filling of basal rice kernels

2000 ◽  
Vol 27 (11) ◽  
pp. 997 ◽  
Author(s):  
Pradeep K. Naik ◽  
Pravat K. Mohapatra
Keyword(s):  
Sucrose Synthase ◽  
Grain Quality ◽  
Oryza Sativa L ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Soluble Carbohydrates ◽  
Ethylene Inhibitors ◽  
Stage Of Development ◽  
Ethylene Action

At the booting stage of development, rice (Oryza sativa L.) plants were treated with chemicals that either inhibited the action or synthesis of ethylene, or produced ethylene. Inhibitors of ethylene action (AgNO3) and synthesis [uniconazole, paclobutrazol, Co(NO3)2] promoted grain filling and quality of the kernels of the basal spikelets of the panicle, while the ethylene-releasing substance CEPA (2-chloroethylphosphonic acid) depressed these characteristics further. The inhibitors depressed the concentration of ethylene of the basal primary branches, but CEPA increased it above the control during the period of grain filling. The treatments were not effective on the superior apical spikelets of the panicle. The ethylene inhibitors improved starch synthesis in the kernels of the basal spikelets, but CEPA reduced it significantly, resulting in accumulation of soluble carbohydrates in the kernels. During the period of grain filling, sucrose synthase activity was higher than that of invertase in the kernels. Activities of sucrose synthase and invertase were higher in the apical than in the basal kernel. The ethylene inhibitors increased activities of both enzymes only in the basal kernel, whereas CEPA reduced activities significantly. Together, the results indicate that starch filling and grain quality of the basally positioned under-developed rice kernels can be affected by ethylene, and that key enzymes of sucrose metabolism are also affected in the process.

Effects of Exposure of Wheat Ears to High Temperature on Dry Matter Accumulation and Carbohydrate Metabolism in the Grain of Two Cultivars. I. Immediate Responses

1991 ◽  
Vol 18 (2) ◽  
pp. 165 ◽  
Author(s):  
CF Jenner
Keyword(s):  
High Temperature ◽  
Sucrose Synthase ◽  
Dry Matter ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Mass Action ◽  
Dry Matter Accumulation ◽  
Partial Explanation ◽  
Calculated Mass ◽  
Percentage Basis

Ears of wheat were exposed for up to 7 days during the grain-filling stage to high temperature (35�C day/25�C night) and metabolic responses in the grain were compared to those in ears maintained at lower temperatures (21�C day/16�C night). Two cultivars of wheat known to differ in their post-anthesis tolerance of high temperature were compared. Raising the temperature resulted in a small increase in the rate of dry matter accumulation: both cultivars responded similarly. Sucrose content of the endosperm was either not affected or increased by raising the temperature. Raising the temperature had differential effects on glucose and fructose content: fructose was substantially reduced while glucose was either unaffected or slightly increased. After raising the temperature the concentrations of all three hexose phosphates measured, glucose-6-phosphate (G-6-P), glucose-1-phosphate (G-1-P) and fructose-6-phosphate (F-6-P), were reduced similarly on a percentage basis and to about the same extent as fructose. The concentration of the sugar nucleotide (UDP-glucose) resulting from the breakdown of sucrose by sucrose synthase was also reduced at high temperature. Judging from calculated mass-action ratios, all three catalytic steps involved in the interconversion of the metabolites mentioned above were close to equilibrium, and only one mass action ratio (for sucrose synthase) was affected by heating: it was doubled. Although temperature clearly resulted in changes in the reaction catalysed by sucrose synthase, it was not clear how temperature had acted. Concentration of the precursor for starch synthesis (ADP-glucose) was slightly lower in both cultivars at the higher temperature. Taken together the responses could provide at least a partial explanation for the smallness of the increase in starch deposition with increase in temperature, but do not explain the different responses of these two cultivars to high temperature.

scholarly journals Genetic Control and High Temperature Effects on Starch Biosynthesis and Grain Quality in Rice

2021 ◽  
Vol 12 ◽  
Author(s):  
Hua Zhang ◽  
Heng Xu ◽  
Yingying Jiang ◽  
Heng Zhang ◽  
Shiyu Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Molecular Mechanisms ◽  
Grain Quality ◽  
Amylose Content ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Eating Quality ◽  
Starch Structure ◽  
Long Time ◽  
Cooking And Eating Quality

Grain quality is one of the key targets to be improved for rice breeders and covers cooking, eating, nutritional, appearance, milling, and sensory properties. Cooking and eating quality are mostly of concern to consumers and mainly determined by starch structure and composition. Although many starch synthesis enzymes have been identified and starch synthesis system has been established for a long time, novel functions of some starch synthesis genes have continually been found, and many important regulatory factors for seed development and grain quality control have recently been identified. Here, we summarize the progress in this field as comprehensively as possible and hopefully reveal some underlying molecular mechanisms controlling eating quality in rice. The regulatory network of amylose content (AC) determination is emphasized, as AC is the most important index for rice eating quality (REQ). Moreover, the regulatory mechanism of REQ, especially AC influenced by high temperature which is concerned as a most harmful environmental factor during grain filling is highlighted in this review.

High Temperature Affects the Activity of Enzymes in the Committed Pathway of Starch Synthesis in Developing Wheat Endosperm

1993 ◽  
Vol 20 (2) ◽  
pp. 197 ◽  
Author(s):  
JS Hawker ◽  
CF Jenner
Keyword(s):  
High Temperature ◽  
Sucrose Synthase ◽  
Starch Synthesis ◽  
Dry Weight ◽  
Grain Filling ◽  
Soluble Starch ◽  
Starch Synthase ◽  
Adpglucose Pyrophosphorylase ◽  
Udpglucose Pyrophosphorylase ◽  
Lower Temperature

Ears of wheat were exposed for up to 10 days during the grain-filling stage to high temperature (35�C) and activities of five enzymes in the sucrose to starch pathway were compared to those in ears maintained at lower temperature (21�C day/16�C night). Two cultivars of wheat known to differ in their post-anthesis tolerance of high temperature were compared. On a per grain basis, the activity of sucrose synthase and of ADPglucose pyrophosphorylase in ears maintained at 21/16�C throughout did not change greatly between days 16 and 32 after anthesis, whereas UDPglucose pyrophosphorylase and soluble starch synthase activities declined with advancing development. Soluble starch synthase activity in grains of heated ears was decreased within 1 day to about one- half of the value in unheated grains, and 3 days' additional heating did not reduce the activity much further. Insoluble starch synthase activity was not significantly reduced by heating. Compared to soluble starch synthase, ADPglucose pyrophosphorylase activity was more slowly affected and decreased to a lesser extent by heat. Sucrose synthase and UDPglucose pyrophosphorylase activities were either not affected or only slightly reduced; part of this reduction could be due to advanced development at the higher temperature. In recovery experiments ears were heated for brief periods and then returned to 21/16�C for a few days. ADPglucose pyrophosphorylase and soluble starch synthase activities recovered in the cooler conditions but the other two enzymes generally only maintained or lost further activity. From a comparison of the activities of these enzymes with the rate of starch deposition, and by taking into account the effects of heating, it is proposed that the influence of heating on final grain dry weight is attributable to the observed reductions of soluble starch synthase activity.

scholarly journals Leaf-derived ABA regulates rice seed development via a transporter-mediated and temperature-sensitive mechanism

2021 ◽  
Vol 7 (3) ◽  
pp. eabc8873
Author(s):  
Peng Qin ◽  
Guohua Zhang ◽  
Binhua Hu ◽  
Jie Wu ◽  
Weilan Chen ◽  
...  
Keyword(s):  
Seed Development ◽  
Starch Synthesis ◽  
Biological Significance ◽  
Grain Filling ◽  
Temperature Sensitive ◽  
Rice Seed ◽  
Dependent Manner ◽  
Long Distance ◽  
Long Distance Transport ◽  
Mechanistic Basis

Long-distance transport of the phytohormone abscisic acid (ABA) has been studied for ~50 years, yet its mechanistic basis and biological significance remain very poorly understood. Here, we show that leaf-derived ABA controls rice seed development in a temperature-dependent manner and is regulated by defective grain-filling 1 (DG1), a multidrug and toxic compound extrusion transporter that effluxes ABA at nodes and rachilla. Specifically, ABA is biosynthesized in both WT and dg1 leaves, but only WT caryopses accumulate leaf-derived ABA. Our demonstration that leaf-derived ABA activates starch synthesis genes explains the incompletely filled and floury seed phenotypes in dg1. Both the DG1-mediated long-distance ABA transport efficiency and grain-filling phenotypes are temperature sensitive. Moreover, we extended these mechanistic insights to other cereals by observing similar grain-filling defects in a maize DG1 ortholog mutant. Our study demonstrates that rice uses a leaf-to-caryopsis ABA transport–based mechanism to ensure normal seed development in response to variable temperatures.

scholarly journals Computer-Assisted Segmentation of Videocapsule Images Using Alpha-Divergence-Based Active Contour in the Framework of Intestinal Pathologies Detection

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
L. Meziou ◽  
A. Histace ◽  
F. Precioso ◽  
O. Romain ◽  
X. Dray ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Active Contour ◽  
Standard Technique ◽  
Poor Quality ◽  
Computer Assisted ◽  
Contour Segmentation ◽  
Semiautomatic Segmentation ◽  
Different Types ◽  
Statistical Similarity ◽  
Wireless Capsule

Visualization of the entire length of the gastrointestinal tract through natural orifices is a challenge for endoscopists. Videoendoscopy is currently the “gold standard” technique for diagnosis of different pathologies of the intestinal tract. Wireless capsule endoscopy (WCE) has been developed in the 1990s as an alternative to videoendoscopy to allow direct examination of the gastrointestinal tract without any need for sedation. Nevertheless, the systematic postexamination by the specialist of the 50,000 (for the small bowel) to 150,000 images (for the colon) of a complete acquisition using WCE remains time-consuming and challenging due to the poor quality of WCE images. In this paper, a semiautomatic segmentation for analysis of WCE images is proposed. Based on active contour segmentation, the proposed method introduces alpha-divergences, a flexible statistical similarity measure that gives a real flexibility to different types of gastrointestinal pathologies. Results of segmentation using the proposed approach are shown on different types of real-case examinations, from (multi)polyp(s) segmentation, to radiation enteritis delineation.

Occurrence of Toxigenic Molds in Brazilian Cheese

1992 ◽  
Vol 55 (3) ◽  
pp. 187-191 ◽  
Author(s):  
MARTA HIROMI TANIWAKI ◽  
ARIENE GIMENES FERNANDES VAN DENDER
Keyword(s):  
Water Activity ◽  
High Water ◽  
Penicillium Species ◽  
High Carbohydrate ◽  
Different Types ◽  
Carbohydrate Contents

Several samples of cheese obtained from regular retailers in Campinas, Brazil, were examined for molds and mycotoxins. Strains of Aspergillus and Penicillium were isolated and evaluated for their potential for producing toxins. Two of the isolated Penicillium species produced citrinin, while another produced patulin. However, no mycotoxins were detected in any of the cheese samples tested. Experiments with different types of cheese and a semisynthetic cheese were carried out in order to verify production of citrinin and patulin. It was observed that citrinin may be produced in cheese with high water activity and in semisynthetic cheese. However, patulin does not appear to be stable in cheese, even in semisynthetic cheese with high water activity and high carbohydrate contents.

scholarly journals Physical monitoring and advice: absence of evidence is not evidence of absence

2015 ◽  
Vol 21 (2) ◽  
pp. 75-77
Author(s):  
Katharine Smith
Keyword(s):  
Mental Illness ◽  
Physical Health ◽  
Health Monitoring ◽  
Poor Quality ◽  
Future Research ◽  
Cost Benefits ◽  
Cochrane Reviews ◽  
Different Types ◽  
Physical Health Problems ◽  
General Physical

SummaryIndividuals with severe mental illness have increased rates of physical health problems and reduced life expectancy. As a vulnerable population, they have been identified as needing increased physical health monitoring and treatment. The first of two Cochrane reviews considered here assessed the evidence for the benefit of monitoring but found no studies that could be included. The second reviewed the evidence for provision of general physical healthcare advice. Although the results were suggestive of benefit, the evidence, where available, was of poor quality. These reviews highlight an important area for future research to evaluate the relative health and cost benefits of different types of intervention.

Novel molecular and cell biological insights into function of rice α-amylase

Amylase ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Toshiaki Mitsui ◽  
Akihito Ochiai ◽  
Hiromoto Yamakawa ◽  
Kentaro Kaneko ◽  
Aya Kitajima-Koga ◽  
...  
Keyword(s):  
Intracellular Transport ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Binding Pocket ◽  
Rice Grain ◽  
Active Site Cleft ◽  
Key Factor ◽  
Organ Specific ◽  
Basic Biology ◽  
Grain Chalkiness

Abstract α-Amylases have been of interest in diverse fields for many years because of their importance in basic biology, agriculture, and industry. Starch hydrolysis in plants has been studied extensively in germinating cereal seeds. It is generally accepted that α-amylases are secretory enzymes with a pivotal role in the breakdown of starch reserves in the endosperm. Intriguingly, however, recent investigations reveal that some α-amylases degrade starch in the plastids of living cells. The recent solving of the crystal structure of rice AmyI-1 isoform shows that the binding pocket of starch binding site 1 situated outside of the active site cleft interacts with the substances other than oligosaccharides. These findings provided novel insights into structural and cell biological aspects of α-amylase functions in intracellular transport, organelle targeting, and organ-specific actions. Under global warming, abnormal high temperatures during rice grain filling increase grain chalkiness, resulting in yield loss. Intensive “omics” analyses of developing caryopses and mature grains grown under heat stress showed the downregulation of starch synthesis enzymes and the upregulation of α-amylases. Transgenic studies using ectopic overexpression and suppression of α-amylase revealed that α-amylase is a key factor in grain chalkiness. Here we discuss unique new functions of α-amylase in rice cells.

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