Fructans from Elongating Leaf Bases Are a Source of Carbon for Regrowth after Defoliation In \u3ci\u3eLolium perenne\u3c/i\u3e

A detailed study of carbohydrate metabolism in perennial ryegrass (Lolium perenne L.) during the first 48 h of regrowth showed that the decline in fructan concentration occurred not only in the differentiation zone (30-60 mm from leaf base), but also in the elongation zone of the elongating leaf bases. Unlike other soluble carbohydrates, the net deposition rate of fructose remained positive and even rose during the first day following defoliation. FEH (fructan exohydrolase) activity, which was maximum in the differentiation zone before defoliation, increased in all segments but peaked in the elongation zone after defoliation. Taken all together, these data strongly suggest that fructans stored in the leaf growth zone were hydrolysed and recycled in that zone to sustain leaf growth, i.e. the restoration of active photosynthesis, immediately after defoliation