Recent advances in the genetic transformation of trees

As the commercial production of transgenic annual crops becomes a reality i n many parts of the world, many people wonder if the genetic engineering of perennial trees will allow their eventual commercialization. Not long ago, trees were considered to be recalcitrant material for most molecular biolo gy techniques, including genetic transformation. However, transgenes for sh ortening the juvenile phase or for phytoremediation purposes have now been incorporated, and the alteration of lignin biosynthesis and increased cellu lose accumulation in forest trees have also been accomplished. For long-liv ed tree species, new questions arise regarding the stability of integration and expression of foreign genes. Biosafety considerations, including trans gene dispersion through the pollen and advances in strategies to avoid this , are also important.