Prevention of flower formation in dicotyledons

Prevention of flower formation is important, for example for preventing the spread of transgenes from genetically modified plants or the spread of non-native species, for increasing vegetative growth or preventing the formation of allergenic pollen. The aim of this study was to determine whether flowering of dicotyledonous plants can be prevented by genetic manipulation without harmful effects on vegetative growth. Here we describe isolation of the BpMADS1 gene (similar to SEP3, formerly AGL9) from birch and show that it is expressed only in the inflorescences. In tobacco and Arabidopsis, the expression of BpMADS1::GUS was also virtually inflorescence-specific. Transgenic tobacco and Arabidopsis containing a BpMADS1::BARNASE construct grew well. In one tobacco line the formation of the inflorescence was completely prevented; in several other lines the flowers lacked stamens and carpels and therefore were sterile. The final dry weights of the shoots of the sterile tobacco lines were 140–200% of those of controls. In Arabidopsis, some of the transgenic lines containing the BpMADS1::BARNASE construct formed inflorescences. Some of these lines formed never flowers and some others formed occasionally single fertile flowers. Some other lines did not form inflorescences, but formed up to about one hundred leaves, even in long-day conditions. These results suggest that formation of flowers or inflorescences in widely different dicotyledonous plants could be prevented using the BpMADS1::BARNASE construct and that prevention of flowering may lead to increased vegetative mass.