Transformation of Lilium ‘Sorbonne’ (oriental hybrids) with anthocyanin regulatory gene B1/C1.

The Lilium is the one of world’s leading cut flowers and commodity flowers, but low transformation efficiencies make it difficult to reproduce genetically modified cultivars, which limits the development of breeding. Thus, the establishment of a rapid, efficient and reproducible transformation protocol for Lilium is very important. Expression of the metabolic regulation gene causes the accumulation of anthocyanins in plant cells, resulting in varied colors of plant organs easy to observe. As a visual reporter, the metabolic regulation gene makes the transformed plants easily distinguishable even only by their color appearance at the early stage. In this study, the Agrobacterium-mediated genetic transformation system of Lilium ‘Sorbonne’ (oriental hybrids) was optimized by using the bulblet scales as receptor materials and the anthocyanin regulatory gene B1/C1 as the target gene. The resistance of plantlets from ‘Sorbonne’ to glyphosate was studied for culture selection, and the optimum concentration was 2.1 mg/L. Seven different types of modified Murashige and Skoog (MS) media in both inoculation and co-cultivation media were evaluated, and a dramatic increase in the rate of resistant plantlets 18.31±1.71% was observed when MS medium was used after removing macro elements. Under this condition, using the inoculation and co-cultivation media containing 6% maltose (instead of 3% sucrose) could improve the rate of resistant plantlets to 22.27±3.48%. A 42 ℃ heat shock treatment for 1.5 min followed by the ultrasonic power 120 W for 20 s brought the highest rate of resistant plantlets 26.80±2.24%. Some resistant plantlets transformed with B1/C1 by Agrobacterium-mediation were obtained after the preliminary screening. PCR screening and Southern blot results identified one single copy positive Gly-resistant plantlet. Analysis of PCR, Southern blot and anthocyanin content showed that exogenous genes were well integrated in the genome of Lilium ‘Sorbonne’ (oriental hybrids) and expressed in leaves, petiole and bulb.