Method for enhancing cellulose and modifying lignin biosynthesis in plants

An isolated polynucleotide sequence is described to comprise a cellulose synthase promoter of SEQ ID NO:3, a sequence conservative variant thereof, or a functional fragment thereof which binds to a transcription factor in a plant cell. The polynucleotide is described to be a stress-inducible promoter, to comprise at least one MSRE (mechanical stress regulatory element), which can be a tree. A method of increasing expression of a cellulose synthase in a plant involves delivering into the plant a cDNA encoding a protein; and a method for reducing the expression of a cellulose synthase in a plant comprises delivering into the plant a DNA in an antisense orientation. Methods for increasing or reducing cellulose biosynthesis in a plant are also described.