Overexpression of PsnSuSy1, 2 genes enhances secondary cell wall thickening, vegetative growth, and mechanical strength in transgenic tobacco.

Two homologs PsnSuSy1 and PsnSuSy2 from poplar played largely similar but little distinct roles in modulating sink strength, accelerating vegetative growth and modifying secondary growth of plant. Co-overexpression of them together resulted in small but perceptible additive effects. Sucrose synthase (SuSy) acts as a crucial determinant of sink strength by controlling the conversion of sucrose into UDP-glucose, which is not only the sole precursor for cellulose biosynthesis but also an extracellular signaling molecule for plants growth.