Dehiscence-related expression of an Arabidopsis thaliana gene encoding a polygalacturonase in transgenic plants of Brassica napus

Pod dehiscence in Arabidopsis thaliana is accompanied by an increase in the expression of a polygalacturonase (PG). The gene encoding this mRNA has be en characterized and shown to have extensive homology to a similar PG gene from Brassica napus. The A. thaliana PG promoter was fused to beta-glucuron idase (GUS) and the expression of this reporter gene analysed in transgenic B. napus plants. The GUS activity was detected throughout the dehiscence z one of pods from 35 d after anthesis and expression was restricted to those cells that undergo cell separation. Expression was also detectable at the junction between the seed and the funicular tissue and in mature anthers of flowers. Transgenic plants containing the PG promoter fused to barnase wer e sterile as a consequence of the anthers failing to undergo dehiscence. Fe rtilization of PG barnase plants resulted in the development of pods that e xhibited a reduced capacity to shatter. The role of PG during cell separati on processes in plants is discussed.