Modification of flowering time in Osteospermum ecklonis L. by CONSTANS gene.

摘要

Altered onset of flowering in crop plants can be achieved by modifying the expression of flowering-time genes. In a few cases, these genes can change the flowering time of species unrelated to the plant from which they were isolated. We pursued thisstrategy to modify the flowering characteristics of the ornamental plant O. ecklonis. The flowering-time gene CONSTANS (CO) from Arabidopsis thaliana Landsberg erecta was the candidate in our work. This choice was based on literature demonstrating thatArabidopsis thaliana transgenic plants containing extra copies of the CO gene flower earlier than wild type plants, suggesting that CO expression is sufficient to trigger flowering irrespective of day length. The CO cDNA was cloned in the expression vector pGREEN under the control of the constitutive promoter 35S. Genetic transformation of leaf tissue was performed using Agrobacterium tumefaciens strain AGL1. CO constitutive expression was detected in a checked transgenic clone. The flowering performance of potted transgenic plants was monitored in the greenhouse in comparison to control plants. 35SCO plants produced 30% more flowers than control, retained their ability to flower in June when control plants entered vegetative phase and were still ableto produce new flower buds in August.