Jill M. Farrant

Drought tolerance in agriculture

Plant water deficit stress is considered to be one of the greatest threats to world agriculture and, in the coming decades, is likely to be exacerbated by the effects of global climate change (FAO, 2008). It is predicted that by 2050, climate change in Africa will significantly affect agriculture and in some areas could lead to the complete abandonment of cropping (Thornton et al., 2009). A considerable increase in agricultural productivity can be brought about by the production of drought-tolerant crops and pasture grasses. Planting of such crops will increase both the length of the growing season and the area where such crops can be grown, and will accommodate fluctuations in climatic conditions associated with climate change.

Currently, several different approaches are being taken to address the problem of decreased water availability for agricultural purposes, including conventional plant breeding, genetic modification, hormonal and chemical treatments. To date none of these have been successful in the long term (that is, for many successive generations) but most importantly, none thus far have been able to confer tolerance to severe drought. The ability to withstand severe water deficit (desiccation) is common in the seeds of most species but vegetative tissues of most plants are extremely sensitive to water deficit. There are, however, some 300 species of angiosperms, many endemic to Southern Africa, in which the vegetative tissues are tolerant of near complete water loss. These desiccation tolerant “resurrection plants” (Gaff, 1989) serve as ideal models for identifying the characteristics which enable tolerance of water deficit stress. Research has been conducted on several species of resurrection plants in order to gain an understanding the mechanisms of desiccation tolerance (DT) in resurrection plants (for reviews see Gaff, 1989; Alpert, 2006; Farrant, 2007; Farrant et al., 2007; Moore et al., 2009; Oliver, 1996; Oliver et al., 2005; Vicar et al., 2004). To date such studies have been exclusively fundamental in nature and the research discipline specific, with most studies focusing exclusively on the molecular genetic changes (Collett et al., 2004; Rodriguez et al., 2010; Zhengbin et al., 2011), with others being either physiological and ultrastructural (Cooper and Farrant, 2004; Farrant, 2000; Farrant et al., 2003; Georgieva et al., 2007; Norwood et al., 1999; Sherwood and Farrant, 1996; Sherwood et al., 1998; Tuba et al., 1996; Vander Willigen et al., 2001; 2004 inter alia) or biochemical and metabolic (Dace et al., 1998; Kranner and Birtic, 2005; Moore et al., 2005, 2006, 2007; Peters et al., 2007; Whittaker et al., 2004; Shao et al., 2005) in nature. We use a systems biology approach in which we utilize several disciplines in attempt to achieve a greater understanding of the mechanisms of desiccation tolerance utilized by a variety of resurrection plants (reviewed in Farrant, 2007; Farrant et al., 2007; Moore et al., 2009; Moore and Farrant, 2011). Furthermore, we use such fundamental studies to identify key protectants that might be used for production of drought tolerant crops and pasture grasses using a bioengineering approach (Mundree et al, 2002; Gawe et al., 2006; Iyer et al., 2007; Moore and Farrant, 2011).


Extract from Physiological response of selected eragrostis species to water-deficit stress


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