Transgenic Lilium longiflorum plants containing the bar-uidA gene controlled by the rice RPC1, Agrobacterium rolD, mas2, and CaMV 35S promoters

Abstract

Lilies are grown in the field for bulb production where they are susceptible to infection by Pratylenchus penetrans, the root lesion nematode. These migratory nematodes feed on roots and often physically disrupt the root tissues when many nematodes enter and move throughout the root to feed. The goal of this study was to find a root-specific or root-preferred promoter because of our interest in genetic engineering of lilies for nematode resistance. Several promoters, the Agrobacterium rolD and mas2, CaMV 35S, and rice RPC1 were examined in transgenic Lilium longiflorum, Easter lily, plants that contained the bar-uidA fusion gene under each promoter. Histochemical staining showed that the rolD, mas2, and CaMV 35S promoters directed gus gene expression in the cortex and stele of transformed roots. Gus expression was limited to the stele of roots with the rice RPC1 promoter making it unsuitable for engineering nematode resistance. The mas2 promoter was found to be expressed primarily in roots rather than shoots whereas the CaMV 35S promoter expressed well in both roots and shoots. Levels of gus specific activity were relatively high for both the mas2 and CaMV 35S promoter in roots but low with the rolD promoter. Because the mas2 promoter had relatively high levels of gus specific activity in roots and not shoots, and expression was throughout cortex and stele tissues of the roots, mas2 appears to be a promising promoter for engineering resistance to root lesion nematodes in Lilium longiflorum.