JXB Advance Access originally published online on August 28, 2003
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Journal of Experimental Botany, Vol. 54, No. 391, pp. 2313-2321,
October 1, 2003
© 2003 Oxford University Press
Investigation into the ability of roots of the poikilohydric plant Craterostigma plantagineum to survive dehydration stress
Received 30 January 2003; Accepted 3 July 2003
,1
1 School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK
2 Chemical Physiology of Plants, Institute of Plant Physiology, University of Vienna Althanstr. 14, A-1091 Wien, Austria
* Present address: Agricultural Biotechnology Centre, PO Box 411, H-2101 Gödöllö, Hungary. To whom correspondence should be addressed. Fax: +44 (0)1273 678433. E-mail: BAFY2{at}sussex.ac.uk
Abbreviations: RWC, relative water content; PFP, pyrophosphate-fructose 6-phosphate 1-phosphotransferase; PFK, phosphofructokinase; GAPDH, glyceraldehyde phosphate dehydrogenase; LEA, late embryogenesis abundant proteins.
The ability of the root system of the poikilohydric plant Craterostigma plantagineum to survive dehydration was investigated. The data presented here reveal that the root system is capable of surviving dehydration, but shortly after rehydration the root system senesces. Two weeks after rehydration the growth of a complete new root system is initiated. During dehydration sucrose accumulates from 36 to a maximum of 111 µmol g–1 DW in the roots. It is suggested that the accumulation of sucrose protects the root system during dehydration. There are major stores of stachyose in the roots of Craterostigma (making up over 40% of the dry weight of the tissue) and during dehydration these stores are metabolized. It is suggested that these stachyose stores act as carbohydrate reserves for the synthesis of sucrose. However, over 350 µmol g–1 DW stachyose is metabolized in the roots, which is well in excess of that required for the accumulation of sucrose observed. It is likely that the stachyose reserves in the root system are translocated to other regions of the plant to support carbohydrate metabolism during dehydration of the tissue. During rehydration, the stachyose reserves return to their original level within 96 h. There is no change in the elevated sucrose content of the roots over this period. Thus the roots maintain the protective properties of sucrose much longer than they are needed. The maintenance of high sucrose contents in rehydrating roots is discussed as a possible survival strategy against recurrent desiccation events.
Key words: Carbohydrate metabolism, root senescence, root system, stachyose, sucrose.
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