Tree defenses against insects

Abstract

Our understanding of individual resistance mechanisms against insects, and especially against pathogens, has improved tremendously during the last decade (Heath and Boller, 2002). This progress has largely been achieved by studying plants (such as cotton, tomato, or Arabidopsis) with suitable traits for experimental work. Trees share just the opposite characteristics: long life span, large size, architectural complexity, and an often short and distinct period of leaf growth. Only saplings can be studied effectively under experimental laboratory conditions; it is not clear, however, to what extent the defenses of saplings are similar to those of mature trees. Hence the defenses of woody plants are not well known; presumably, trees employ mechanisms that are widespread in the plant kingdom. The specific features, compared to herbs, also offer opportunities to study mechanisms of plant defense, and their interactions, that are not obvious in short-lived hosts.