Activation of sucrose-metabolizing enzymes and stimulation of sucrose uptake by auxin and sucrose in eggplant (Solanum melongena L.)

1997 ◽  
Vol 150 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Tae-Ho Lee ◽  
Akira Sugiyama ◽  
Jhon Ofosu-Anim ◽  
Kiyotoshi Takeno ◽  
Hajime Ohno ◽  
...  
2001 ◽  
Vol 126 (6) ◽  
pp. 676-680 ◽  
Author(s):  
Yasuyoshi Hayata ◽  
Xin-Xian Li ◽  
Yutaka Osajima

To clarify the cause of low sucrose accumulation in seedless `Crest Earl's' netted muskmelon [Cucumis melo L. (Reticulatus Group)] fruit induced by CPPU, the activity level of sucrose metabolizing enzymes was compared between seeded and seedless fruit. CPPU promoted growth of the ovary in both pollinated and nonpollinated flowers until 10 days after anthesis (DAA), and thereafter the growth rate of nonpollinated fruit was lower than in the controls. Sucrose accumulation of seedless fruit remained lower than in seeded fruit, but there was no difference in fructose and glucose content between seeded and seedless fruit. Acid invertase activity declined sharply 20 DAA in seeded and seedless fruit, and was hardly detectable at 35 DAA, when sucrose accumulation began. Neutral invertase (NI) activity in both seeded and seedless fruit decreased from 20 DAA until 35 DAA; thereafter, NI activity in seeded fruit remained relatively constant, with a small but insignificant increase in maturity. Sucrose synthase (SS-c: sucrose cleavage direction) activity in seeded fruit decreased from 20 to 30 DAA, and then increased as fruit matured, while SS-c activity in seedless fruit did not change during development. Sucrose phosphate synthase (SPS) activity in seeded fruit increased from 25 to 30 DAA and remained relatively constant until harvest. SPS activity in seedless fruit declined gradually from 30 to 45 DAA, then remained at a low level. Sucrose synthase (SS-s: sucrose synthesis direction) activity in seeded fruit increased rapidly after 30 DAA, concomitant with sucrose accumulation. In contrast, SS-s activity in seedless fruit increased only slightly after 30 DAA indicating levels of SS-s activity are closely related to sucrose accumulation in parthenocarpic seedless muskmelons. Chemical name used: [1-(2-chloro-4-pyridyl)-3-phenylurea] (CPPU).


Author(s):  
Łukasz P. Tarkowski ◽  
Vicky G. Tsirkone ◽  
Evgenii M. Osipov ◽  
Steven Beelen ◽  
Willem Lammens ◽  
...  

The metabolism of sucrose is of crucial importance for life on Earth. In plants, enzymes called invertases split sucrose into glucose and fructose, contributing to the regulation of metabolic fluxes. Invertases differ in their localization and pH optimum. Acidic invertases present in plant cell walls and vacuoles belong to glycoside hydrolase family 32 (GH32) and have an all-β structure. In contrast, neutral invertases are located in the cytosol and organelles such as chloroplasts and mitochondria. These poorly understood enzymes are classified into a separate GH100 family. Recent crystal structures of the closely related neutral invertases InvA and InvB from the cyanobacterium Anabaena revealed a predominantly α-helical fold with unique features compared with other sucrose-metabolizing enzymes. Here, a neutral invertase (AtNIN2) from the model plant Arabidopsis thaliana was heterologously expressed, purified and crystallized. As a result, the first neutral invertase structure from a higher plant has been obtained at 3.4 Å resolution. The hexameric AtNIN2 structure is highly similar to that of InvA, pointing to high evolutionary conservation of neutral invertases.


2010 ◽  
Vol 1 (1) ◽  
pp. 2 ◽  
Author(s):  
Deepak Ganjewala

Here we report the effects of SNP, a nitric oxide donor on sucrose metabolizing enzymes, acid and alkaline invertase (EC 3.2.1.26 and 3.2.1.153) and ubiquitous alkaline phosphatase (EC 3.1.3.1) in four lemongrass varieties viz., Krishna, Cauveri, Nima and Cheerharit. For the study, two 15 d lemongrass tillers were cut and immediately dipped into the test tubes containing SNP solution (5 mL) of variable strength (1 to 5 mM) and one without SNP (as control); kept for 4 h under mild sunlight. The results revealed that moderate SNP concentration (2 mM) was most effective, caused drastic reduction (40%) in protein content in var. Nima followed by Krishna (33%), Cauveri (17%) and Cheerharit (12%). In contrast, SNP (1 mM) has impressively enhanced protein content in all the lemongrass varieties. The SNP (2 mM) markedly inhibited the activity of acid invertase by 38% in Cheerharit, 35% Nima and 28% Cauveri whereas and alkaline invertase by 21, 28 and 24% respectively in var. Cheerharit, Nima and Krishna. Similarly, SNP (5 mM) severely inhibited (~ 63%) the activity of the ALP in lemongrass var. Cauveri and Nima, 50% in Krishna and relatively less 23% in Cheerharit as compared to the control. However, in var. Nima, 50% loss in ALP activity had already been occurred after 2 mM SNP treatment. These results primarily suggests that NO interferes sucrose metabolism by anonymously hindering the activity of acid and alkaline invertase and ubiquitous alkaline phosphatase in lemongrasses.


Sugar Tech ◽  
2011 ◽  
Vol 13 (2) ◽  
pp. 114-122 ◽  
Author(s):  
Suresh K. Batta ◽  
Deeksha ◽  
K. S. Thind ◽  
Pritpal Singh ◽  
S. K. Uppal

Holzforschung ◽  
2001 ◽  
Vol 55 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Elisabeth Magel ◽  
Amani Abdel-Latif ◽  
Rüdiger Hampp

Summary In trunks of Juglans nigra and the hybrid J. major × J. regia, the presence of non-structural carbohydrates, sucrose synthesizing and degrading enzymes, and their correlation with heartwood formation was investigated. Contents of starch and sucrose were highest in the youngest sapwood, decreased with increasing age of the tissue, and were absent in the heartwood. Pools of the monosaccharides glucose and fructose were low in the sapwood, and fructose was absent from the heartwood. Glucose transiently increased at the sapwood heartwood boundary in trunks of the hybrid. In black walnut stems, however, glucose started to accumulate within the transition zone and reached considerable amounts in the heartwood. Cold-adaptation in walnut wood was characterized by accumulation of soluble sugars. Sucrose formation was enabled by enhanced rates of sucrose-phosphate synthase (SPS, EC 2.4.1.14). Mid-winter starch-sugar interconversion was accompanied by increases in the activity of sucrose synthase (SuSy, EC 2.4.1.13; black walnut), or acid invertases (EC 3.2.1.26; hybrid). In the tissues undergoing heartwood formation, sucrose breakdown was enhanced from late summer until early winter. Sucrolysis was dominated by acid invertases with minor contribution of sucrose synthase. The catalytic activity of UDP-glucose pyrophosphorylase (EC 2.7.7.9), involved in the metabolization of the sucrose cleavage products, followed this seasonal trend and showed elevated activities from late summer until early winter. These data are further proof for the earlier made hypothesis (Hauch and Magel 1998) that the in situ synthesis of heartwood flavonoids relies on an interaction between primary (sucrose) and secondary metabolism. Flavonoids, however, constitute only a minor fraction in the heartwood of walnut and the bulk of heartwood phenolics seem to derive from transformation of phenolic precursors. Therefore, these recent findings together with earlier data are taken as evidence that more than one type of heartwood formation exists.


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