Shinro Yamamoto

Mechanism of Phleinase Induction in the Stem Base of Orchardgrass after Defoliation

Summary The mechanism of phleinase (s-D-fructan fructohydrolase, EC 3.2.1.80) synthesis in the stem bases oforchardgrass was studied using anti-phleinase serum. Phleinase activity in excised basal stems increased about 5-fold in 48 h after cuttring, but the increase was suppressed by treatment with cordycepin, puromycin or cycloheximide. Density of a cross-reacting band produced by Western blotting of the crude enzyme from the stem increased after defoliation. Activity and amount of phleinase, and incorporation of 14 C-leucine into the enzyme in excised stems increased over 50 h in concert. These results suggest that increase in phleinase activity in defoliated stem bases derives from de novo synthesis of the enzyme.

Functional differentiation between the inner and outer leaves in a mechanical support by a pseudostem of Veratrum album subsp oxysepalum

The pseudostem of Veratrum album subsp. oxysepalum consists of radical leaves, which have tubular and concentrically aggregated petioles. We examined a hypothesis that the major role of the inner leaves is to raise the leaf blades higher for increased photosynthesis, while that of the outer leaves is to mechanically support the inner leaves at the expense of displaying their leaf blades. The removal of outer leaves resulted in the collapse of the remaining inner leaves, showing outer leaves provide important support for inner leaves. The estimation of mechanical properties for the constituting leaves revealed that inner leaves possess greater mass of leaf blades for their capacity of mechanical support them compared to outer leaves. These results uphold the hypothesis that the primary role of inner leaves is to display leaf blades for photosynthesis, while that for outer leaves is to mechanically support the less stable inner leaves.