Short-term induction of alkaloid production in lupines Differences between N2-fixing and nitrogen-limited plants.

We used N2-fixing and nonfixing lupines to examine the effects of plant nutrition on short-term alkaloid production in damaged leaves. Three different treatments were used: damaged leaves from N2-fixing plants; undamaged leaves from these damaged, N2-fixing plants; and damaged leaves on nitrogen-limited, nonfixing plants. Relative to controls, alkaloids increased in concentration more quickly in the N2-fixing than in the nitrogen-limited plants. The magnitude of this increase in alkaloids was correlated with the initial alkaloid concentration. These results suggest that nitrogen-rich plants may benefit from faster and higher alkaloid induction than nitrogen-limited plants. In addition, the detailed dynamics of individual alkaloids are consistent with earlier proposals for the mechanism of lupine alkaloid induction.