Molecular biology for stress management

Drought is a meteorological term and an environmental event, defined as a water stress due to lack of or insufficient rainfall and/or adequate water supply (Toker et al., 2007). The impact of drought and importance of drought tolerance to legume crops has been discussed in other sections of this book (Chapters 8, 9, 10, 19, 20, etc.). Drought tolerance is a complex trait associated with several physiological attributes. In the agronomical sense, drought resistance refers to the ability of a plant to produce its economical product with minimum loss in a water-deficit environment, relative to normal water conditions. In a genetic sense, the mechanisms of drought resistance can be grouped into three categories, viz., escape, avoidance and tolerance (Turner et al., 2001; Malhotra and Saxena, 2002). These mechanisms are inter-related and there is no fixed line of demarcation.