Basic principles of terminal flower formation

Abstract

Studies of efflorescences of the mutants bractea and terminal flower1 and double mutant bra tfl1 of Arabidoipsis thaliana (L.) Heynh. have shown that the presence of a developed leaf in the node preceding the terminal flower is a necessary condition for the formation of the terminal flower perianth. This means that perianth cannot develop in an abracteose efflorescence of terminal flower. The second necessary condition for the terminal flower formation is a sufficient level of expression of the genes responsible for floral morphogenesis. Combination of these two conditions suffices for the development of a terminal flower with perianth. Since the general principles of organization are close for most flower plants, it can be stated that if the abracteose efflorescence is terminated by a flower with perianth, this is a consequence of forcing the lateral flower into the terminal position.