Present status and future prospects of transgenic approaches for drought tolerance

Drought causes severe stress on plants and constrains crop production. New strategies are essential to overcome water loss and stabilize crop yield in agriculture in view of global climate change. Conventional methods employing direct selection for high-yielding cultivars or indirect identification of secondary traits under stressful conditions are useful, but these procedures are time-consuming and labor-intensive. In contrast, the newer “omic” technologies can more quickly help us acquire a molecular and physiological understanding of drought tolerance in plants, whereas transgenic strategies hold promise in using specific transgenes to minimize the deleterious effects of water deficiency. A substantial amount of research utilizing mutant and transgenic plant lines exhibiting altered expression of drought-responsive genes has significantly contributed to promoting drought protection. These genes can be broadly categorized into three groups based on their functions: regulatory genes, genes related to metabolites and osmoprotectants, and those associated with posttranslational modification. This chapter focuses on current progress on some transgenic approaches for enhancing drought tolerance in plants. Examples of successful applications involving various transcription factors, and strategies related to abscisic acid and osmolyte metabolism, as well as protein phosphorylation and farnesylation, are discussed