tion in agriculture has already occurred. Worldwide, in 1999, about 28 million hectares of transgenic
plants were being grown. It has been predicted that this area will be tripled in the next 5 years [125].
V. CONCLUDING REMARKS
Photosynthesis is the engine of life for almost all organisms on earth because it provides food, energy,
and oxygen for them and is also the basis of yield formation in crop plants. High photosynthetic effi-
ciency, including high photosynthetic rate in strong light and high quantum yield in weak light, should be
used as a selection criterion for high-yielding varieties.
The first green revolution has achieved great success in increasing crop yield since the 1960s, but
it is losing its edge. Scientists are seeking a new revolution in order to feed the increasing population
of the world. For the new green revolution, the central objective is improvement of the photosynthetic
efficiency of crops and the sharp tool is gene engineering. The tool is powerful not only in under-
standing molecular mechanisms for the regulation of photosynthetic efficiency but also in engineering
crops with desirable characteristics. Cooperative efforts made by scientists of many disciplines are ab-
solutely necessary to the success of the new revolution. The proper choice of targets of engineering
crops depends on a breakthrough in the comprehensive study on the regulatory mechanisms of the pho-
tosynthetic efficiency.
ACKNOWLEDGMENTS
Some studies of the authors cited in this chapter were supported by the State Key Basic Research and De-
velopment Plan (No. G1998010100) and the National Natural Science Foundation of China (No.
39730040). We thank Professor Tian-Duo Wang for critically reading the manuscript and giving useful
suggestions.
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830 XU AND SHEN