ABSTRACT
A better understanding of the mechanisms by which trees perceive environmental cues and transmit signals to activate adaptive responses is of fundamental importance in stress-biology research. Knowledge about stress-signal transduction is also crucial for breeding and engineering tree tolerance to abiotic stress. Stress responses and tolerance mechanisms involve the prevention or alleviation of cellular damage, the re-establishment of homeostasis and growth resumption. Stress resistance mechanisms within trees fall into three categories: avoidance mechanisms; tolerance mechanisms; and escape mechanisms. This chapter diagrammatically shows how trees respond to urban landscape stresses. Higher activities of ROS-scavenging enzymes are associated with stress-tolerant tree genotypes compared to susceptible ones; suggesting inherently high antioxidant enzyme content plays an important role in tolerance against photo-oxidative damage. Flavonoids are capable of controlling the development of individual organs and the whole plant; and, hence, to contribute to stress-induced morphogenic responses of plants.
