Leaves 5 and 6 (as defined by Weaver et al. (1998)) were collected at
27 and 37 DAG. The distal 15 mm of each leaf was harvested and leaf samples were pooled. Pools contained the leaves of 9 –12 plants. Pooled leaves were dried for 48 h at 80 ˚C. Dried leaves were ground to a powder using a mortar and pestle and dry weight was deter- mined.