• Preface
• Increasing water shortage and global food supply
• Increasing accumulation of salt in soils through unsustainable irrigation practice
• How plants manage to survive during drought stress and in saline environments
• Drought and salinisation: Two abiotic stress factors for plants
• Morphologic strategies
• Physiologic strategies
• Recent research on transgenic drought- and salt-tolerant plants
• Functional proteins
• Osmoprotectants (osmotic adjustment)
• Protection factors of macromolecules
• Membrane proteins
• Detoxification enzymes
• Regulatory Proteins
• Transcription factors
• Prospects and Risks
• Can transgenic crops contribute substantially in defeating world hunger?
• Specific risks of transgenic drought- and salt-tolerant crops
• Alternative solutions without the use of genetic engineering References

Preface

Facing the increasing global freshwater scarcity, many scientists work on engineering transgenic drought-resistant plants worldwide. Due to high salt levels in large areas of arable land, salt tolerance is an important trait. Thus, it plays a big role in genetic crop engineering of the last years. However, using poor quality irrigation water was a major reason for salinisation of arable land, so called induced salinisation.

The development of transgenic stress tolerant plants is very slow which is probably due to the lack of knowledge about the physiological and biochemical mechanisms of stress tolerance in plants. Thus, complicated genetic manipulation is required.

Corresponding traits rely most likely on a large number of genes and complex regulatory systems. But over the last years, there were increasing research efforts in engineering transgenic stress-tolerant crops (Schmitz & Schütte 2000).

The first commercialization of transgenic stress-tolerant plants will take place between five and ten years at the earliest. Field trials with such plants only have very marginal relevance until now. Increasing water shortage and global food supply Water supply is the major limiting factor in producing more food in the future. Agriculture still accounts for at least 70% of the worlds total water usage (Inocencio et al. 2003)1. At present, around 18% of the global farmland is irrigated (more than 240 million hectares) and up to 40% of the global food supply is produced on this land (Supper 2003; Somerville & Briscoe 2001).

Especially, some developing countries of the south suffer under grave water scarcity. The resulting problems are serious and will aggravate in the future due to increasing usage of aquifers, a growing competition for water resources and further climate changes. Repeated droughts and persistent water shortage is threatening especially the ability of the African continent to feed its people. According to the UN Global Environment Outlook 2000, fourteen African countries are subject to water stress or water scarcity and a further eleven will join them by 2025. Large parts of Asia are as well submitted to acute water shortage and freshwater supply1. According to a study of the International Water Management Institute (IWMI), one third of the world's population will live in arid regions in the year of 2025 . In the last four years, some of the US states of the south had to face water shortage due to some drought periods. For the first time, farmers in Georgia were paid to abstain from irrigating their crops (NN 2002b).

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