Engineering Salinity and Water-Stress Tolerance in Crop Plants. Getting Closer to the Field.

Abiotic stress is the primary cause of crop plant yield losses worldwide. Drought and salinity stress are the major environmental challenges faced by agriculture. Improving yield production and stability under stressful environments is needed to fulfil the food demand of the ever-growing world population. Numerous genes associated to plant response(s) to drought and salinity stress have been identified and characterized, in most cases, in the model plant Arabidopsis. However, while many of these genes are potential candidates for improving tolerance to abiotic stress, only a small proportion were transferred into crop plants. Further, transgenic crop plants overexpressing the genes of interest were, in most cases, tested under artificial conditions in the laboratory or controlled greenhouse. Thus, while many reports on drought and salinity tolerance in transgenic plants have been published, there is urgent need to test these traits under field conditions. In this chapter, we discuss recent advances in engineering drought and salinity tolerance in crop plants with emphasis on yield and the needs to close the gaps between the laboratory and the field conditions.