Transformation of Kalanchoe blossfeldiana for Ethylene Insensitivity

Kalanchoe blossfeldiana leaf explants were infected and transformed with Agrobacterium tumefaciens harbouring the plasmid pBEO210. This construct contains the mutated ethylene receptor gene etr1-1 from Arabidopsis thaliana under the control of the flower-specific fbp1-promoter from Petunia. Flowers of eight putative transgenic T0 plants exhibiting a significant NPTII protein content showed lower ethylene sensitivity than control plants after ethylene exposure. One of the transgenic lines (line 324) showed altered vegetative and flowering architecture and infertility. The T0 line with lowest ethylene sensitivity (line 300) was analyzed for expression and copy-number of the etr1-1 gene and crossed with the ethylene-sensitive cultivar 'Celine' to create progeny. The etr1-1 gene was found to be expressed in petals and stamens but not in carpels, sepals and leaves, confirming that the fbp1 promoter induces etr1-1 expression in a flower-specific manner. Southern blotting, segregation data from the crossing, and PCR analysis of progeny plants revealed two unlinked T-DNA copies in line 300, which are segregated in Mendelian fashion to T1 plants. T1 plants with only one T-DNA copy are as ethylene resistant as the T0 plants and may be useful in breeding to confer ethylene insensitivity to other Kalanchoe cultivars.