[Cotton laccase gene overexpression in transgenic Populus alba var. pyramidalis and its effects on the lignin biosynthesis in transgenic plants].

Using petioles as explants, a cotton laccase cDNA (GaLA C1) was introduced into Populus alba var. pyramidalis by A. tumefaciens-mediated transformation. PCR and Southern blot analysis indicated that transgene was stably integrated into the genome of transformants. Enzyme assay showed that laccase activity was obviously increased in transformants. As compared with untransformed control, total lignin content in all tested transgenic lines was elevated in varying degrees (as highest as 21.5%). Histochemical staining of lignin further confirmed that overexpressing GaLA C1 could result in increased lignin content in transformants. Together, our data strongly suggested that GaLA C1 may participate in lignin synthesis and this is the first direct transgenic evidence for the involvement of plant laccases in lignification.