scholarly journals Analysis of Phenotypic Characteristics and Sucrose Metabolism in the Roots of Raphanus sativus L.

2021 ◽  
Vol 12 ◽  
Author(s):  
Ji-Nam Kang ◽  
Jung Sun Kim ◽  
Si Myung Lee ◽  
So Youn Won ◽  
Mi-Suk Seo ◽  
...  

The taproot of radish (Raphanus sativus L.) is an important sink organ; it is morphologically diverse and contains large amounts of secondary metabolites. Sucrose metabolism is believed to be important in the development of sink organs. We measured the amounts of glucose, fructose, and sucrose in the roots of sixty three radish accessions and analyzed the association between the sugar content and the root phenotype. Fructose content correlated with the root color and length characteristics, glucose was the most abundant sugar in the roots, and the sucrose content was very low, compared to that of the hexoses in most of the accessions. Expression analysis of the genes involved in sucrose metabolism, transportation, starch synthesis, and cell wall synthesis was performed through RNA sequencing. The genes encoding sucrose synthases (SUSY) and the enzymes involved in the synthesis of cellulose were highly expressed, indicating that SUSY is involved in cell wall synthesis in radish roots. The positive correlation coefficient (R) between the sucrose content and the expression of cell wall invertase and sugar transporter proteins suggest that hexose accumulation could occur through the apoplastic pathway in radish roots. A positive R score was also obtained when comparing the expression of genes encoding SUSY and fructokinase (FK), suggesting that the fructose produced by SUSY is mostly phosphorylated by FK. In addition, we concluded that sucrose was the most metabolized sugar in radish roots.

1994 ◽  
Author(s):  
Deborah P. Delmer ◽  
Prem S. Chourey

The goal of this work was to understand the role of the enzyme sucrose synthase (SuSy) in synthesis of cellulose and callose in plants. The work resulting from the this grant leads to a number of conclusions. SuSy clearly plays diverse roles in carbon metabolism. It can associate with the plasma membrane of cells undergoing rapid cellulose deposition, such as cotton fibers, developing maize endosperm, gravistimulated pulvini, and transfer cells of the cotton seed. It is also concentrated at sites of high callose deposition (tapetal cells; cell plates). When SuSy levels are lowered by mutation or by anti-sense technology, cell walls undergo degeneration (maize endosperm) and show reduced levels of cellulose (potato tubers). In sum, our evidence has very much strengthened the concept that SuSy does function in the plasma membrane to channel carbon from sucrose via UDP-glucose to glucan synthase complexes. Soluble SuSy also clearly plays a role in providing carbon for starch synthesis and respiration. Surprisingly, we found that the cotton seed is one unique case where SuSy apparently does not play a role in starch synthesis. Current evidence in sum suggests that no specific SuSy gene encodes the membrane-associated form, although in maize the SS 1 form of SuSy may be most important for cell wall synthesis in the early stages of endosperm development. Work is still in progress to determine what does control membrane localization - and the current evidence we have favors a role for Ca2+, and possibly also protein phosphorylation by differentially regulated protein kinases. Finally, we have discovered for the first time, a major new family of genes that encode the catalytic subunit of the cellulose synthase of plants - a result that has been widely cited and opens many new approaches for the study of this important plant function.


PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259100
Author(s):  
Siyi Zhao ◽  
Yanqiao Zhu ◽  
Wenwen Liu ◽  
Xiaoshan Wang ◽  
Han Wang ◽  
...  

Excess copper (Cu) in soil due to industrial and agricultural practices can result in reduced plant growth. Excess Cu resulted in severely retarded root growth with severe discoloration of Alfalfa (Medicago sativa) and Medicago truncatula. Growth in the presence of hydrogen peroxide resulted in similar symptoms that could be partially recovered by the addition of the reductant ascorbic acid revealing damage was likely due to oxidative stress. The addition of proanthocyanidins (PAs) in the presence of Cu prevented much of the damage, including plant growth and restoration of lignin synthesis which was inhibited in the presence of excess Cu. Transcriptome analyses of the impact of excess Cu and the amelioration after PAs treatment revealed that changes were enriched in functions associated with the cell wall and extracellular processes, indicating that inhibition of cell wall synthesis was likely the reason for retarded growth. Excess Cu appeared to induce a strong defense response, along with alterations in the expression of a number of genes encoding transcription factors, notably related to ethylene signaling. The addition of PAs greatly reduced this response, and also induced novel genes that likely help ameliorate the effects of excess Cu. These included induction of genes involved in the last step of ascorbic acid biosynthesis and of enzymes involved in cell wall synthesis. Combined, these results show that excess Cu causes severe oxidative stress damage and inhibition of cell wall synthesis, which can be relieved by the addition of PAs.


2013 ◽  
Vol 289 (3) ◽  
pp. 1243-1256 ◽  
Author(s):  
Mark J. Lee ◽  
Fabrice N. Gravelat ◽  
Robert P. Cerone ◽  
Stefanie D. Baptista ◽  
Paolo V. Campoli ◽  
...  

The cell wall of Aspergillus fumigatus contains two galactose-containing polysaccharides, galactomannan and galactosaminogalactan, whose biosynthetic pathways are not well understood. The A. fumigatus genome contains three genes encoding putative UDP-glucose 4-epimerases, uge3, uge4, and uge5. We undertook this study to elucidate the function of these epimerases. We found that uge4 is minimally expressed and is not required for the synthesis of galactose-containing exopolysaccharides or galactose metabolism. Uge5 is the dominant UDP-glucose 4-epimerase in A. fumigatus and is essential for normal growth in galactose-based medium. Uge5 is required for synthesis of the galactofuranose (Galf) component of galactomannan and contributes galactose to the synthesis of galactosaminogalactan. Uge3 can mediate production of both UDP-galactose and UDP-N-acetylgalactosamine (GalNAc) and is required for the production of galactosaminogalactan but not galactomannan. In the absence of Uge5, Uge3 activity is sufficient for growth on galactose and the synthesis of galactosaminogalactan containing lower levels of galactose but not the synthesis of Galf. A double deletion of uge5 and uge3 blocked growth on galactose and synthesis of both Galf and galactosaminogalactan. This study is the first survey of glucose epimerases in A. fumigatus and contributes to our understanding of the role of these enzymes in metabolism and cell wall synthesis.


1995 ◽  
Author(s):  
Susan Lurie ◽  
John Labavitch ◽  
Ruth Ben-Arie ◽  
Ken Shackel

The overall goal of the research was to understand the processes involved in the development of woolliness in peaches and nectarines. Four specific hypotheses were proposed and in the course of the research evidence was gathered t support two of them and to not support two others. The hypotheses and a summary of the evidence are outlined below. 1. That woolliness arises from an imbalance between the activities of the cell wall pectin degrading enzymes. Using 'Flavortop' nectarines and 'Hermoza' peaches as model systems, storage regimes were manipulated to induce or prevent woolliness. The expression (mRNA abundance), protein content (Western blotting), and activity of polygalacturonase (PG) and pectin esterase (PE) were followed. Expression of the enzymes was not different, but activity and the ratio between PG and PE activities were quite different in fruits developing woolliness or ripening normally. This was also examined by looking at the substrate, the pectin moiety of the cell wall, and i woolly fruit there were more high molecular weight pectins with regions of non-methylated galacturonic acid residues. Taking an in vitro approach it was found a) that PE activity was stable at 0oC while PG activity decreased; b) incubating the calcium pectate fraction of the cell wall with PE extracted from peaches caused the polymers to form a gel characteristic of the visual woolly symptoms in peaches. 2. That continued cell wall synthesis occurs during storage and contributes to structural changes i cell walls and improper dissolution and softening after storage. We tried to adapt our technique of adding 13C-glucose to fruit discs, which was used successfully to follow cell wall synthesis during tomato ripening. However, the difference in sugar content between the two fruits (4% in tomato and 12% in peach) meant that the 13C-glucose was much more diluted within the general metabolite pool. We were unable to see any cell wall synthesis which meant that either the dilution factor was too great, or that synthesis was not occurring. 3. That controlled atmosphere (CA) prevents woolliness by lowering all enzyme activities. CA was found to greatly reduce mRNA abundance of the cell wall enzymes compared to regular air storage. However, their synthesis and activity recovered during ripening after CA storage and did not after regular air storage. Therefore, CA prevented the inhibition of enzyme activation found in regular air storage. 4. That changes in cell wall turgor and membrane function are important events in the development of woolliness. Using a micro pressure probe, turgor was measured in cells of individual 'O'Henry' and 'CalRed' peaches which were woolly or healthy. The relationship between firmness and turgor was the same in both fruit conditions. These data indicate that the development and expression of woolliness are not associated with differences in membrane function, at least with regard to the factors that determine cell turgor pressure. In addition, during the period of the grant additional areas were explored. Encoglucanase, and enzyme metabolizing hemicellulose, was found to be highly expressed air stored, but not in unstored or CA stored fruit. Activity gels showed higher activity in air stored fruit as well. This is the first indication that other components of the cell wall may be involved in woolliness. The role of ethylene in woolliness development was also investigated at it was found a) that woolly fruits had decreased ability to produce ethylene, b) storing fruits in the presence of ethylene delayed the appearance of woolliness. This latter finding has implication for an inexpensive strategy for storing peaches and nectarines.


2017 ◽  
Vol 199 (17) ◽  
Author(s):  
Rachel E. Bosserman ◽  
Patricia A. Champion

ABSTRACT Mycobacterial 6-kDa early secreted antigenic target (ESAT-6) system (ESX) exporters transport proteins across the cytoplasmic membrane. Many proteins transported by ESX systems are then translocated across the mycobacterial cell envelope and secreted from the cell. Although the mechanism underlying protein transport across the mycolate outer membrane remains elusive, the ESX systems are closely connected with and localize to the cell envelope. Links between ESX-associated proteins, cell wall synthesis, and the maintenance of cell envelope integrity have been reported. Genes encoding the ESX systems and those required for biosynthesis of the mycobacterial envelope are coregulated. Here, we review the interplay between ESX systems and the mycobacterial cell envelope.


2020 ◽  
Vol 0 (4) ◽  
pp. 29-32
Author(s):  
B.M. GAREEV ◽  
◽  
A.M. ABDRAKHMANOV ◽  
G.L. SHARIPOV ◽  
◽  
...  

The photoluminescence of carbon quantum dots synthesized from natural honey and mixtures of honey and sugar has been studied. An increase in the sugar content leads to a decrease in the photoluminescence intensity without changing the shape of the luminescence spectrum of these quantum dots aqueous solutions, which is associated with a decrease in the yield of their synthesis in the sugar presence. The discovered effect can be used to detect sugar in honey. When examining five different market samples of flower honey using this method, two of them showed a significant decrease in the photoluminescence intensity. A laboratory test for compliance with GOST 19792-2017 Standard requirements established an excess of the sucrose content in these samples. Luminescent determination of sugar in honey does not require complicated equipment and can be used to develop a new analytical method for determining the sugar content in counterfeit natural honey.


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