Expression of the Arabidopsis gai gene under its own promoter causes a reduction in plant height in chrysanthemum by attenuation of the gibberellin response

Several transgenic chrysanthemum (Chrysanthemum morifolium Ramat.) lines have been produced that express the Arabidopsis thaliana gai (gibberellic acid insensitive) gene under its own promoter. These transformants exhibit a range of dwarf phenotypes, the extent of dwarfing being related to the reduction in the response to gibberellin in each transgenic line. Physiological measurements of growth, chlorophyll content and flowering time demonstrate that the extent of the transgene effects correlate with the level of transgene expression. Production of many ornamental crops relies heavily on the use of expensive and harmful agrochemicals in order to produce a blemish free and uniform product. We demonstrate the feasibility of producing a dwarf (pot) chrysanthemum without the need for growth retardant chemicals through heterologous expression of the mutant Arabidopsis gai gene driven from its own promoter. © 2002 Elsevier Science Ireland Ltd. All rights reserved.