ABSTRACT
This chapter explores whether a possible causative conjunction exists between the hormonal changes and the response to stress. The first approach is to correlate the endogenous levels of phytohormones with physiological response of plant to stress. The second experimental approach uses genetic variants, naturally occurring or obtained by different manipulations, and correlates the hormonal balance in plants with the variability in physiological traits. Photosynthesis and carbon metabolism are very basic processes that, in plants, are affected by stress and modified by hormones. It can be argued that the frequent lack of correlation between endogenous hormone levels and the severity of the stress or the intensity of the response refutes the hypothesis. A general hypothesis for the central role of phytohormones in the regulation of plant response to stress is proposed based on the following evidence. Plants respond to different stresses in a similar manner; response is the result of many coordinated processes; and all phytohormones are involved in this coordination.
