Glycinebetaine Biosynthesis and Accumulation in Unstressed and Salt-Stressed Wheat

Abstract

McDonnell, E. and Wyn Jones, R. G. 1988. Glycinebetaine biosynthesis and accumulation in unstressed and salt-stressed wheat.—J. exp. Bot. 39: 421-430. A preliminary study was made of the pathway of glycinebetaine biosynthesis in wheat and compared with that of spinach. The data obtained provided further evidence that there is a fundamental difference in the biosynthetic pathway between the Gramineae and the Chenopodiaceae. A detailed study was then made of the pattern of glycinebetaine accumulation during development of unstressed and salt-stressed wheat. The content of glycinebetaine in the leaves of unstressed plants increased as each leaf developed and decreased rapidly thereafter. In salt-stressed leaves an initial increase in glycinebetaine content was observed which also coincided with leaf expansion. The glycinebetaine content of the stressed leaves then began to decrease only to increase again. The roots and grain of both stressed and unstressed plants had high glycinebetaine contents at the onset of germination but these declined rapidly as the plants grew. A possible link between glycinebetaine biosynthesis and membrane lipid biosynthesis in wheat is discussed.