Ectopic expression of the PttKN1 gene in Cardamine hirsuta mediated via the floral dip method.

PttKN1 gene (Populus tremula × P. tremuloides KNOTTED1) was isolated from the vascular cambium of a hybrid aspen. Previous studies on transformed plants with the PttKN1 gene suggested that it plays roles in plant development (typically in meristem initiation), maintenance and organogenesis in simple-leaved species. To investigate the gene functions further, sequence analysis of the deduced amino acid was conducted. The results suggested that the gene belongs to the class I KNOX gene (KNOTTED1-like homeobox genes) family and might play important roles in plant development by coding a transcription factor. The gene was introduced into Cardamine hirsuta using the floral dip method mediated via Agrobacterium tumefaciens. The primary transformed plants were obtained via kanamycin selection. Compared to the wild type, the kanamycin resistant plants demonstrated several morphological alterations, such as abnormal cotyledons, abnormal shoot meristem, flattened stem, and lobed and cup-shaped leaves. RT-PCR results showed that the above five types of kanamycin resistant plants expressed the same specific PttKN1 gene band. This suggested that the morphological alterations were caused by the insertion and expression of the gene. However, these phenotypes were similar to other PttKN1 transformed plants, despite the fact that C. hirsuta is a species with compound leaves and the other species have simple leaves. Therefore, the functions of the PttKN1 gene on compound-leaf species have yet to be investigated via the comparison between related species such as Arabidopsis thaliana and C. hirsuta.