Constitutive expression of β-glucuronidase gene fused with stress-inducible promoter of the pathogenesis-related 1a protein gene of tobacco in transgenic Kalanchoe blossfeldiana

Pathogenesis-related la (PR1a) promoter derived from PR1a protein gene of tobacco has been reported to conduct stress-induced or salicylic acid (SA) -induced expression in tobacco, potato, lettuce and torenia. Constitutive expression, an abnormal response, of the promoter was reported only in an interspecific hybrid of Nicotiana glutinosa x Nicotiana debneyi. We report constitutive expression of beta-glucuronidase (GUS) gene fused with PR1a promoter in transgenic Kalanchoe blossfeldiana. The chimeric gene (PR1a/GUS) was introduced into K. blossfeldiana by Agrobacterium-mediated transformation. The expression level of GUS gene among 45 individual transformants were analyzed. The activity level in non-treated leaf of each plant was varied from near-zero to about 17000 nmoles 4 MU/mg protein/30min. Thus, several plants showed very high activity even at healthy (not-induced) condition. The activity level was almost same between non-treated and SA-treated leaf in most of transformants. These results suggested that the stress-inducible promoter of tobacco did not conduct its nature function but showed abnormal response, constitutive expression, in K. blossfeldiana.