ARABIDOPSIS - ITS USE IN THE GENETIC AND MOLECULAR ANALYSIS OF PLANT MORPHOGENESIS

In the last decade, the weed Arabidopsis thaliana has come to prominen ce as a major new model system for investigating genetic and molecular aspects of developmental plant morphology. Extensive genetic and mole cular information about the Arabidopsis genome, facilitated by interna tional collaborations and the production of novel mutagenic systems, h as enabled a vast array of mutants to be identified, most of which rev eal nuclear genes that control different aspects of plant developmenta l processes. An ever increasing number of these newly identified genes have been isolated and within the next few years an overall view of t he molecular control of plant development is likely to emerge. Particu larly prevalent amongst these Arabidopsis mutants are those which alte r morphogenic processes either by changes in differentiation patterns of specific cell types, homeotic conversion of entire structures or ab normal patterns of cell division. Mutants in the control of morphogene sis of most parts of the Arabidopsis plant have been identified and ch aracterized. The most abundant classes are in embryogenesis, including seedling pattern formation, root morphogenesis, floral morphology (in cluding pollen and anther formation) and mutants affecting shoot apica l meristem morphology. The first genes to be isolated from morphologic al mutants have been identified as transcription factors capable of co ntrolling expression of other gene classes as part of a hierarchy of g ene control. The relative ease with which many interesting and potenti ally important genes in morphogenesis have been revealed by identifica tion of mutants makes it highly likely that with the aid of Arabidopsi s thaliana, an understanding of the extremely complex molecular basis of plant morphogenesis may at last be within reach.