Regulatory Gene Variation in Higher Plants

Abstract

Publisher Summary This chapter reviews a number of genetic systems in higher plants, for which regulatory genes are identified and shown to affect the expression of specific structural gene products (that is, proteins). The chapter also discusses some experimental approaches that are applicable for studying the gene–enzyme systems in higher plants. Several of the genetic systems to be considered involve the regulation of storage proteins associated with the developing and mature seed of crop plants. In addition to these, a number of gene–enzyme systems in maize (Zea mays L.) are studied, in which the regulatory loci appear to function in controlling the level of enzyme protein or activity. Several novel approaches are used to isolate presumed regulatory mutations. One of the promising approaches is to select for temperature-sensitive or nitrate reductase-deficient mutants using plant tissue culture techniques. In tobacco, a temperature-sensitive mutant (ts4) is regenerated from tissue culture. This mutation has a pleiotropic effect on the activities of phenylalanine ammonia lyase, nitrate reductase (NR), ornithine decarboxylase, and S-adenosyl methionine decarboxylase but does not have an effect on a number of other enzymes involved in nitrate assimilation.