ABSTRACT
Since their establishment on land between 400 and 450 mya (Cleal and Thomas, 1999), plants have been confronted with a variety of biotic and abiotic stresses. The sessile nature of plants forced them to develop stress tolerance mechanisms which allowed plants to colonize a wide diversity of habitats from the Arctic to Antarctica. There has been a tremendous amount of research undertaken to elucidate how plants respond to and tolerate stress and the contributions of stress tolerance to plant distribution and biogeography (Brown et al., 1996; Gaston, 1996; Lowry and Lester, 2006). However, the nature of plant adaptation and subsequent establishment in high stress habitats remains unresolved (Leone et al., 2003; Maggio et al., 2003; Tuberosa et al., 2003). Although genetic mechanisms of plant stress tolerance are complex and not fully elucidated, they are thought to be based on adaptive changes in the plant genome (Robe and Grif ths, 2000; Givnish, 2002; Pan et al., 2006; Schurr et al., 2006). Interestingly, all plants have the ability to perceive abiotic stress and transduce signals at the cellular, tissue, and whole plant level to mitigate the impacts of stress, yet relatively few species thrive in high stress habitats (Bohnert et al., 1995; Iba, 2002; Bartels and Sunkar, 2005).
