PHYSIOLOGICAL COMPLEXITY AND PLANT GENETIC MANIPULATION

One of the limiting factors in the development of new cultivars in a r easonable time using recombinant DNA techniques, is an inability to pr edict the interaction between the introgressed gene(s) and the host ge nome and metabolism. This review presents a survey of the literature o n the constraints determining the coherence between alien sequences an d their products, and the organization of the receiving genome and its physiological equilibrium. An hypothesis supported by preliminary exp erimental data is put forward that such constraints derive from co-ada ptation during the evolution of gene complexes driven by external sele ction pressure, and by changes in genes coding for key factors of plan t metabolism. Conclusions are finally drawn on a series of possible me thods to be used in genetic engineering, in relation to breeding pract ice, compatible with the rules governing the organization of physiolog ical networks.