Plant and Cell Physiology, 2003, Vol. 44, No. 9 901-908
© 2003 Oxford University Press
Alteration of Citrate Metabolism in Cluster Roots of White Lupin
1 Laboratory of Plant Cell Technology, Faculty of Agriculture, Gifu University, 1-1, Yanagido, Gifu, 501-1193 Japan
2 Forestry Research Institute, Oji Paper Co., Ltd., 24-9 Nobono, Kameyama, Mie, 519-0212 Japan
Organic acid excretion plays a key role in the superior Pi-acquisition of barely soluble inorganic P sources from soils. Seedlings of white lupin (Lupinus albus L.) grown for 37 d in –P nutrient solution showed typical –P symptoms, such as low P content, increased root/shoot ratio and the development of cluster roots which released large amounts of citrate. Citrate concentration in the cluster roots was 21.5 µmol (g FW)–1, which corresponded to a 4.3- and 2.6-fold increase of +P and –P root apexes, respectively. Cluster roots possessed higher phosphoenolpyruvate carboxylase and phosphoenolpyruvate phosphatase activity than those in +P root apexes, which could result in increasing the supply of substrate for citrate synthase. On the other hand, the cytosolic pathway which converts citrate to 2-oxoglutarate consists of aconitase and NADP-specific isocitrate dehydrogenase activity that was lower in the cluster roots than in +P root apexes, and may contribute to citrate accumulation. Thus, metabolic balance with these alterations would play an important role in increasing citrate concentration in the cluster roots. The molecular characterization of NADP-specific isocitrate dehydrogenase indicated that the cytosolic isoenzyme functions as a hetero-dimer, and that the activity would be regulated by the transcript levels for both isoforms.
3 Corresponding author: E-mail, koyama{at}cc.gifu-u.ac.jp; Fax, +81-58-293-2911.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. P. Hammond and P. J. White Sucrose transport in the phloem: integrating root responses to phosphorus starvation J. Exp. Bot., January 1, 2008; 59(1): 93 - 109. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kobayashi, O. A. Hoekenga, H. Itoh, M. Nakashima, S. Saito, J. E. Shaff, L. G. Maron, M. A. Pineros, L. V. Kochian, and H. Koyama Characterization of AtALMT1 Expression in Aluminum-Inducible Malate Release and Its Role for Rhizotoxic Stress Tolerance in Arabidopsis Plant Physiology, November 1, 2007; 145(3): 843 - 852. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W.-H. Zhang, P. R. Ryan, and S. D. Tyerman Citrate-Permeable Channels in the Plasma Membrane of Cluster Roots from White Lupin Plant Physiology, November 1, 2004; 136(3): 3771 - 3783. [Abstract] [Full Text] [PDF]
|
|