Differences in the contents of total sugars, reducing sugars, starch and sucrose in embryogenic and non-embryogenic calli from Medicago arborea L.

The total sugars, reducing sugars, starch and sucrose in embryogenic and no n-embryogenic calli from explants (cotyledons, petioles, hypocotyls and lea ves) obtained from Medicago arborea L. seedlings were evaluated. Total suga rs were the major components in the calli and no significant differences be tween embryogenic and non-embryogenic calli were observed. In contrast, imp ortant differences between the embryogenic and non-embryogenic calli were o bserved for reducing sugars, the highest levels being observed in embryogen ic calli. The highest starch levels were found in non-embryogenic calli dev eloped in MS medium. During the development of somatic embryogenesis very l ow starch levels in the callus were found. During the first months of cultu re, no significant differences in the sucrose content were found between ca lli that produced embryos and those that did not. The most important differ ences in sucrose were seen between calli transferred to medium F0, which ha d the greatest embryogenic capacity, and those transferred to medium F6, wh ich inhibited embryogenesis. In the latter case, an increase in sucrose was observed. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.