Genetic analysis of osmotic adjustment in crop plants

Abstract Phenomenon of osmotic adjustment Land plants have been coping with water stress for somePlant water deficit is a component of several different 400 million years, ever since they first left the seas andstresses, including drought, salinity and low temper-colonized dry land (Thomas, 1997). Because land plantsature, which severely limit plant growth and crop experience constant fluctuations in the availability ofproductivity. Genetic modification of plants to allow water, they have evolved adaptive features to search forgrowth and yield under unfavourable conditions is an and absorb water through their root systems, to preventimportant component of the solution to problems of excessive transpirational water loss using cuticles andenvironmental stress. While disagreement and even stomata, and to adjust their physiology and metabolismconfusion may characterize some of the discussions for continued growth and survival (Zhu et al., 1997;on what constitutes a significant and an effective Zhang et al., 1996).mechanism of drought resistance in crop plants, Although plants are exposed to many types of environ-osmotic adjustment (OA) is receiving increasing mental stresses, osmotic stress, whether by drought,recognition as a major mechanism. This paper starts salinity or low temperature, constitutes the most seriouswith the review of OA functions, genetic variation and limitation to plant growth, productivity and distributioninheritance, and theories and principles involved i