ABSTRACT
Phytohormones are small molecules that regulate growth and development of plants in addition to responding to various changes in the environment. Modification, synthesis, distribution and/or signal transduction of phytohormones coordinate with growth and developmental processes inclusive of stress tolerance to support the survival of plants. Gibberellin (GA), one of the most important classes of plant growth-promoting hormone against abiotic stress, is reported to play an important role. Levels of GA and its signalling pathway influence on plant growth restriction of plants under different stress conditions like temperature, osmotic stress, and salinity. Increased GA biosynthesis and signal transduction promote growth in plants to combat against shading and submergence. It has been reported that GA signalling is also related to tolerance of different types of abiotic stresses. The regulation at the transcriptional level of GA metabolism is important in the regulation of the GA pathway, but there is enough evidence that depicts the interrelationship of the GA signalling molecule DELLA with others, and it indicates that GA signalling crosstalks with different hormonal signalling pathways to react to various abiotic stresses. The chapter focusses on the evidence for the importance of GA as a plant growth regulator and the regulation of the signal transduction pathway of GA when exposed to abiotic stress. The GA signalling mechanisms for regulation of stress tolerance are also discussed.
