Regulation of the cytosolic fructose-1,6-bisphosphatase by post-translational modification and protein level in drought-stressed leaves of sugarbeet
1992
Harn, C. | Daie, J.
Sugarbeet plants (Beta vulgaris, L.) were grown in a growth chamber and subjected to a slow-developing (in vivo) period of drought stress by withholding water. During an 8 day period, several parameters were monitored. A gradual and consistent decline was observed in the activity of the cytosolic fructose-1,6-bisphosphatase (FBPase) during the first 3-4 days of stress. During this initial period, leaf water potential had declined from -0.8 MPa, but no significant changes were observed in hexose, sucrose and starch contents, levels of FBPase protein and transcript and sucrose-phosphate synthase (SPS) transcript. Major changes in all parameters occurred during the latter stages of stress. At the end of this period, water potential was -4.3 MPa, sucrose levels increased three fold, starch content declined to less than 10% and FBPase activity was about 40% of controls. SPS activity slightly declined under substrate-saturating conditions but increased (100%) under substrate-limited conditions. SPS transcript slightly declined only in severely stressed leaves. Protein and transcript levels of FBPase also declined, but substantial amounts remained in these leaves suggesting that sugarbeet has a relatively resilient system for sucrose synthesis. During the initial stages, the decline in FBPase activity was coupled with stable protein level, suggesting post-translational modification of the protein. Later, regulation appeared to involve decline in the protein level. The data provide the first evidence for the coarse control of this enzyme in plants.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library