Controlled induction of GUS marked clonal sectors in Arabidopsis

Stably transformed Arabidopsis lines in which GUS marked cell clones are readily produced in response to heat‐shock have been established and characterized. Control of GUS activation is achieved by heat‐shock‐induced FLP recombinase activity which ‘switches on’ expression of a GUS marker gene previously held transcriptionally silent. To obtain efficient GUS sectoring, single insert Arabidopsis lines carrying FLP recombinase under the control of a heat‐shock‐inducible promoter and an FLP‐activatable GUS construct were generated. Analysis of GUS sectoring in lines hemizygous and homozygous for both inserts was conducted after various regimes of heat‐shock were given at various developmental stages. It is shown that GUS sectoring events can be efficiently induced in most vegetative, aerial and sexual structures in Arabidopsis. Furthermore, the frequency of sectoring events, sector size and, to some extent, the tissues in which sectors are generated can be readily controlled by choice of the conditions and timing of heat‐shock used.