Stability of β-glucuronidase gene expression in transgenic Tricyrtis hirta plants after two years of cultivation

Transgenic plants of Tricyrtis hirta carrying the intron-containing β-glucuronidase (GUS) gene under the control of the CaMV35S promoter have been cultivated for two years. Four independent transgenic plants produced flowers 1–2 years after acclimatization, and all of them contained one copy of the transgene as indicated by inverse polymerase chain reaction (PCR) analysis. All the four transgenic plants showed stable expression of the gus gene in leaves, stems, roots, tepals, stamens and pistils as indicated by histochemical and fluorometric GUS assays, although differences in the GUS activity were observed among different organs of each transgenic plant. No apparent gus gene silencing was observed in transgenic T. hirta plants even after two years of cultivation.