Plant growth and productivity are limited in many areas of the world by a wide variety of environmental stresses. This book discusses progress made toward the major goal of uncovering the plant resistance mechanisms to biotic and abiotic stresses; the purpose being to utilise this knowledge in genetic modification of plants for achieving improved stress resistance. This volume achieves a new synthesis in considering the mechanisms of resistance at various levels of organisation -- from individual cells and tissues, through whole plants, to communities. Chapters are written by internationally acknowledged experts, who have a wealth of research and teaching experience. With comprehensive and up-to-date coverage, this book analyses many outstanding problems and poses important questions for future research.