Transgenic cotton over-producing spinach sucrose phosphate synthase showed enhanced leaf sucrose synthesis and improved fiber quality under controlled environmental conditions

2007 ◽  
Vol 63 (6) ◽  
pp. 815-832 ◽  
Author(s):  
Candace H. Haigler ◽  
Bir Singh ◽  
Deshui Zhang ◽  
Sangjoon Hwang ◽  
Chunfa Wu ◽  
...  

The use of elasticity coefficients and flux-control coefficients in a quantitative treatment of control is discussed, with photosynthetic sucrose synthesis as an example. Experimental values for elasticities for the cytosolic fructose 1,6-bisphosphatase and sucrose phosphate synthase are derived from their in vitro properties, and from an analysis of the in vivo relation between fluxes and metabolite levels. An empirical factor α , describing the response of the fructose 2,6-bisphosphate regulator cycle to fructose 6-phosphate is described, and an expression is derived relating α to the elasticities of the enzymes involved in this regulator cycle. The in vivo values for elasticities and α are then used in a modified form of the connectivity theorem to estimate the flux control coefficients of the cytosolic fructose 1,6-bisphosphatase and sucrose phosphate synthase during rapid photosynthetic sucrose synthesis.


2004 ◽  
Vol 31 (7) ◽  
pp. 685 ◽  
Author(s):  
Stephen J. Trevanion ◽  
C. Kate Castleden ◽  
Christine H. Foyer ◽  
Robert T. Furbank ◽  
W. Paul Quick ◽  
...  

The regulation of sucrose-phosphate synthase (SPS, E.C. 2.4.1.14), a key enzyme of sucrose synthesis, was investigated in wheat (Triticum aestivum L.) leaves. Wheat SPS was activated in the light, with an increased affinity for its substrates and the activator glucose-6-phosphate, reduced sensitivity to inhibition by Pi, but no change in maximum catalytic activity. Based on these properties, assays to measure the total activity and activation state of the enzyme were established and validated using several different wheat cultivars, grown under different environmental conditions. As found in previous studies on other species, e.g. spinach, activation appeared to be linked to the prevailing rate of photosynthesis rather than light per se. Long-term exposure to higher light levels increased total SPS activity in the leaves, and some experiments indicated that this response could occur within 1 h of exposure of low-light-grown plants to high light. However, activation of pre-existing enzyme was a more common short-term response to high light. Wheat, like many important cereal species, stores a large amount of sucrose in its leaves. In contrast with spinach, which stores more starch in its leaves, accumulation of sucrose in wheat leaves did not lead to inactivation of SPS or inhibition of sucrose synthesis. In conclusion, the mechanisms linking the rates of sucrose synthesis and photosynthetic CO2 fixation in wheat leaves appear to be similar to those in other species, but the mechanisms involved in short-term feedback inhibition of sucrose synthesis by sucrose, found in starch-storing species, are lacking in wheat.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Iqbal ASIF ◽  
Qiang DONG ◽  
Xiangru WANG ◽  
Huiping GUI ◽  
Hengheng ZHANG ◽  
...  

Abstract Background Nitrogen (N) is important for improving various morphological and physiological processes of cotton but their contribution to fiber quality is still lacking. Aims The current study aimed to explore the relationship between root morphology, subtending leaf physiology, and fiber quality of contrasting N-efficient cotton genotypes in response to N. Methods We analyzed the above parameters of CCRI 69 (N-efficient) and Xinluzao-30 (XLZ-30, N-inefficient) under control (2.5 mmol·L−1) and high N (5 mmol·L−1) conditions. Results The results showed that root morphological traits were increased in CCRI-69 under control conditions than high N. Subtending leaf morphology, chlorophyll and carotenoid contents, free amino acids, and soluble proteins were higher under high N as compared with the control. However, soluble sugars, fructose, sucrose contents, and sucrose phosphate synthase were higher under control conditions than high N across the growth stages. Irrespective of the N conditions, all morphological and physiological traits of cotton subtending leaf were higher in CCRI-69 than XLZ-30. Except for fiber uniformity, fiber quality traits like fiber length, strength, micronaire, and elongation were improved under control conditions than high N. Between the genotypes, CCRI-69 had significantly higher fiber length, strength, micronaire, and elongation as compared with XLZ-30. Strong positive correlations were found between root morphology, soluble sugars, sucrose content, and sucrose phosphate synthase activity with fiber quality traits, respectively. Conclusions These findings suggest that CCRI-69 performed better in terms of growth and fiber quality under relatively low N condition, which will help to reduce fertilizer use, the cost of production, and environmental pollution.


2014 ◽  
Vol 80 (18) ◽  
pp. 5672-5679 ◽  
Author(s):  
Shigeki Ehira ◽  
Satoshi Kimura ◽  
Shogo Miyazaki ◽  
Masayuki Ohmori

ABSTRACTThe filamentous, nitrogen-fixing cyanobacteriumAnabaenasp. strain PCC 7120 accumulates sucrose as a compatible solute against salt stress. Sucrose-phosphate synthase activity, which is responsible for the sucrose synthesis, is increased by salt stress, but the mechanism underlying the regulation of sucrose synthesis remains unknown. In the present study, a response regulator, OrrA, was shown to control sucrose synthesis. Expression ofspsA, which encodes a sucrose-phosphate synthase, andsusAandsusB, which encode sucrose synthases, was induced by salt stress. In theorrAdisruptant, salt induction of these genes was completely abolished. The cellular sucrose level of theorrAdisruptant was reduced to 40% of that in the wild type under salt stress conditions. Moreover, overexpression oforrAresulted in enhanced expression ofspsA,susA, andsusB, followed by accumulation of sucrose, without the addition of NaCl. We also found that SigB2, a group 2 sigma factor of RNA polymerase, regulated the early response to salt stress under the control of OrrA. It is concluded that OrrA controls sucrose synthesis in collaboration with SigB2.


2007 ◽  
Vol 12 (2) ◽  
pp. 137-143
Author(s):  
Miswar Miswar ◽  
Bambang Sugiharto ◽  
Joedoro Soedarsono ◽  
Sukarti Moeljapawiro

Sucrose phosphate synthase (SPS EC 2.3.1.14) plays an important role in partition of assimilated carbon in most plants. SPS catalyses the penultimate reaction in the pathway of sucrose synthesis, in which sucrose-6-phosphate (Suc6P) is synthesized from UDPglucose (UDPG) and fructose-6-P (Fru6P). To increase the capacity of sugarcane in sucrose synthesis, spindle leaves of sugarcane cv R579 were transformed with cDNA SoSPS1 from sugarcane under the control of constitutive promoter (35S CaMV) that constructed in pBI 121 (pKYS) using Agrobacterium tumefaciens. Based on PCR analysis, we have detected the existence of SPS transgene in some lines of transformed sugarcane, called line 4, 5, 6, and 7. The SPS transgene in transformed sugarcane could be expressed into translation level and increased the amount of leaves SPS protein, so the activity of leaves SPS was higher than wild type sugarcane as control. The transformed sugarcane line 4, 5, 6, and 7 showed 1.4–2.9 fold increases in SPS activity and 1,76–2,2 fold increases in leaves sucrose content. Increasing in SPS activity in transgenic sugarcane was coupled by the increase in invertase activity and ratio between sucrose and starch content.


Planta ◽  
1989 ◽  
Vol 177 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Paul Quick ◽  
Gabi Siegl ◽  
Ekkehard Neuhaus ◽  
Regina Feil ◽  
Mark Stitt

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