An investigation into induced plant defences

This laboratory exercise involves techniques that can be used to investigat e induced plant defences. Runner beans are damaged, and the leaves that sub sequently grow are tested for the presence of additional defence mechanisms . A control (undamaged) group is kept for comparison. Induced physical defe nces are indicated by an increase in the density of hairs (trichomes) on th e leaves, and induced chemical defences by a decrease in the palatability o f the leaves. The latter is tested by a bioassay using garden snails. These basic methods can be used to investigate a variety of defensive responses in plants.