TREHALOSE AND TREHALASE IN ROOT-NODULES FROM VARIOUS LEGUMES

Nitrogen-fixing (effective) nodules from various legume-Rhizobium comb inations were analyzed for trehalose and other soluble carbohydrates u sing gas chromatography and for trehalase activity using biochemical a ssays. Whereas the bacterial disaccharide trehalose was present only i n the minority of the nodules, trehalase activity was found in all of them. Extracts from determinate nodules had a higher trehalase activit y than extracts from indeterminate nodules. More detailed studies were done on soybean nodules formed in interactions with two effective and 5 ineffective Bradyrhizobium japonicum strains. Only in effective soy bean nodules colonized by the strain 61-A-101 was trehalose a major so luble carbohydrate. Irrespective of the wildtype strains used, effecti ve soybean nodules contained about 10 nkat trehalase g-1 fresh weight, whereas the ineffective nodules colonized by mutant strains derived f rom these wildtype strains contained 2 to 30 times less trehalase. How ever, a clear correlation between trehalose content and trehalase acti vity could not be established.