Generation of transgenic hybrid aspen that express a bacterial gene for feruloyl-CoA hydratase/lyase (FerB), which is involved in lignin degradation in Sphingomonas paucimobilis SYK-6

Abstract

Transgenic hybrid aspens that expressed a bacterial gene for an enzyme involved in the degradation of hydroxycinnamates, feruloyl-CoA hydratase/lyase (FerB), were produced by Agrobacterium-mediated transformation. The gene was isolated from the bacterium Sphingomonas paucimobilis SYK-6, which is able to degrade a wide variety of monomeric and dimeric lignin-related compounds. The introduced gene was expressed and FerB (vanillin-forming) activity was detected in cell-free extracts obtained from most of the plants. There were no detectable differences between the transgenic plants and wild-type plants, except in one of the transformants 33 that had chlorotic leaves and a lower growth rate. The results of reverse transcription-polymerase chain reaction analysis of endogenous genes for phenylpropanoid biosynthesis suggested that expression of the FerB transgene did not have a significant effect on the expression of endogenous genes in transformants at an early stage of growth, namely in 2-month-old plantlets, even though levels of expression of genes for 4-coumarate:CoA ligase and ferulate 5-hydroxylase were higher in several of the FerB transformants than in the wild-type plants. Our data indicate that genes derived from bacteria can be expressed in woody plants and suggest a new method for manipulating phenylpropanoid biosynthesis and for producing transgenic woody plants with enhanced economic value.