Transient expression of a reporter gene in bulbscales and immature embryos of three Lilium species is affected by 5’upstream sequences and culture conditions

Abstract

In Lilium, a transformation system has not yet been developed. For efficient selection of cells expressing transferred genes following particle bombardment, the effects of 5’upstream regions on the transient expression of the β‐glucuronidase gene (gusA) were estimated in bulbscales and immature embryos of lily. When four plasmids having the gusA gene under the control of the cauliflower mosaic virus (CaMV) 35S, maize alcohol dehydrogenase gene and rice actin gene (Actl) promoters, and the castor bean catalase introm were introduced by particle bombardment, the patterns of transient expression in the bulbscales showed differences among three Lilium species, L. x formolongi, L. dauricum and L. japonicum. In immature embryos of L x formolongi, transient expression was significantly influenced by age of embryos after self‐pollination, duration of culture before bombardment, and culture conditions. Moreover, the transient gusA expression driven by six different 5’upstream regions, including the maize ubiquitin gene promoter and a modified CaMV 35S promoter were compared in both bulbscales and immature embryos. Use of the Actl and modified CaMV 35S promoters resulted in the greatest number of cells that transiently expressed gusA in both types of tissue of L. x formolongi. These two promoters are efficient for use in lily transformation.