Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both sorbitol and sucrose are translocated to, and utilized in, sink tissues of apple (Malus domestica). Considering that antisense suppression of aldose 6-phosphate reductase resulted in lower concentrations of sorbitol and higher concentrations of sucrose in source leaves without altering the vegetative growth of apple trees, it was hypothesized that sorbitol metabolism is down-regulated and sucrose metabolism is up-regulated in shoot tips of the transgenic plants. Carbohydrate measurements indicated that sorbitol concentration was lower whereas sucrose concentration was higher in the shoot tips of transgenic apple plants with decreased sorbitol synthesis compared with the untransformed control. However, the shoot relative growth rate was not altered in the transgenic plants. Sorbitol dehydrogenase (SDH) activity was decreased; acid invertase activity and neutral invertase activity remained the same, whereas sucrose synthase (SUSY) activity was increased in shoot tips of the transgenic plants. The SDH transcript level was lower whereas the SUSY transcript level was higher in shoot tips of the transgenic plants. SDH activity and SDH transcript level were specifically stimulated by exogenous sorbitol fed to the shoot tips via the transpiration stream but were specifically inhibited by sucrose. SUSY activity and SUSY transcript level were dramatically enhanced by sucrose, but decreased by glucose and fructose. Neither acid invertase nor neutral invertase activity responded to sucrose, glucose, fructose, or any other sugars tested. It is concluded that sorbitol dehydrogenase is down-regulated, whereas sucrose synthase is up-regulated in shoot tips of the transgenic apple trees with decreased sorbitol synthesis, leading to homeostasis of vegetative growth. Sorbitol and sucrose act as signal molecules to modulate the expression and activities of sorbitol dehydrogenase and sucrose synthase, both of which play an important role in determining the sink strength of apple shoot tips.
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PMID:Down-regulation of sorbitol dehydrogenase and up-regulation of sucrose synthase in shoot tips of the transgenic apple trees with decreased sorbitol synthesis. 1698 May 95

Peach leaf curl is a disease that affects the leaves of peach trees, and in severe cases all of the leaf can be similarly affected. This study investigated some effects of this disease on the metabolism of peach leaves in which all parts of the leaf were infected. These diseased leaves contained very little chlorophyll and performed little or no photosynthesis. Compared to uninfected leaves, diseased leaves possessed higher contents of fructose and especially glucose, but lowered contents of sucrose, sorbitol and especially starch. The activities of soluble acid invertase, neutral invertase, sorbitol dehydrogenase and sucrose synthase were all higher in diseased leaves, whereas, those of aldose-6-phosphate reductase and sucrose phosphate synthase were lower. The activities of hexokinase and fructokinase were little changed. In addition, immunblots showed that the contents of Rubisco and ADP-glucose phosphorylase were reduced in diseased leaves, whereas, the content of phosphoenolpyruvate carboxylase was increased. The results show that certain aspects of the metabolism of diseased leaves are similar to immature sink leaves. That is photosynthetic function is reduced, the leaf imports rather than exports sugars, and the contents of non-structural carbohydrates and enzymes involved in their metabolism are similar to sink leaves. Further, the effects of peach leaf curl on the metabolism of peach leaves are comparable to the effects of some other diseases on the metabolism of photosynthetic organs of other plant species.
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PMID:Peach leaf curl disease shifts sugar metabolism in severely infected leaves from source to sink. 2801 88

Both sorbitol and sucrose are synthesized in source leaves and transported to fruit for supporting fruit growth in tree fruit species of the Rosaceae family. In apple (Malus domestica), antisense suppression of aldose-6-phosphate reductase, the key enzyme for sorbitol synthesis, significantly decreased the sorbitol concentration but increased the sucrose concentration in leaves, leading to a lower sorbitol but a higher sucrose supply to fruit in these plants. In response to this altered carbon supply, the transgenic fruit had lower concentration of sorbitol and much higher concentration of glucose but similar levels of fructose, sucrose, and starch throughout fruit development relative to the untransformed control. Activities of sorbitol dehydrogenase, fructokinase, and sucrose phosphate synthase were lower, whereas activities of neutral invertase, sucrose synthase, and hexokinase were higher in the transgenic fruit during fruit development. Transcript levels of MdSOT1, MdSDHs, MdFK2, and MdSPS3/6 were downregulated, whereas transcript levels of MdSUC1/4, MdSUSY1-3, MdNIV1/3, MdHKs, and MdTMT1 were upregulated in the transgenic fruit. These findings suggest that the Sucrose cycle and the sugar transport system are very effective in maintaining the level of fructose and provide insights into the roles of sorbitol and sucrose in regulating sugar metabolism and accumulation in sorbitol-synthesizing species.
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PMID:Sugar metabolism and accumulation in the fruit of transgenic apple trees with decreased sorbitol synthesis. 3051 Jul 67

For a comprehensive understanding of gene expression, enzyme activity and sugar concentrations in response to short-term water deficit in apple (Greensleeves), sugar-modulated gene expression and enzyme activities were analyzed. Water stress resulted in the accumulation of sorbitol, glucose, fructose, galactose and starch, accompanied by a significant reduction in photosynthesis and sucrose concentration. In response to short-term water deficits, the activities of aldose-6-phosphate reductase (A6PR; EC 1.1.1.200), sorbitol dehydrogenase (SDH; EC 1.1.1.14), neutral invertase (NINV; EC 3.2.1.26), sucrose synthase (SUSY; EC 2.4.1.13), and fructokinase (FK; EC 2.7.1.4) were higher, whereas cell wall invertase (CWINV; EC 3.2.1.26) and hexokinase (HK; EC 2.7.1.1) activities were lower. In addition, sucrose phosphate synthase (SPS; EC 2.4.1.14) activity increased during the initial stages of dehydration and then decreased as the drought strengthened. Transcript levels of MdA6PR, MdSDH1/2, MdNINV1/2, MdSUSY3, MdFK1/2/4, MdSOT1/2, MdSUC1-3, MdTMT2/3, MdvGT1, MdpGlcT1-4 were upregulated, whereas transcript levels of MdCWINV1/2, MdHK1/2/3/5, and MdTMT1 were downregulated after 6 days of water stress. These findings suggest that the sorbitol metabolism pathway is induced and high levels of hexose derived from photosynthetic products are transported into vacuoles for adjustment to the water deficit. Our results provide insights into the relationships between sugar levels and sugar-modulated gene and enzyme activity in response to the imposition of short-term water stress.
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PMID:Response of sugar metabolism in apple leaves subjected to short-term drought stress. 3117 Jun 40