The Effects of Altered Carbohydrate Metabolism on Plant Growth and Cellulose Biosynthesis

Directed manipulation of the wood chemistry of trees could have huge impacts on both the environmental and economic aspects of wood processing, and more specifically, the pulp and paper industry. The goals of this research were to elucidate the effects of over-expressing genes involved in sucrose metabolism on plant growth and cellulose content (carbohydrate allocation), including: sucrose synthase (SuSy), sucrose phosphate synthase (SPS), invertase and UDP-glucose pyrophosphorylase (UGPase). It has previously been shown that SUSY converts sucrose directly into UDPG and fructose; SPS synthesizes sucrose phosphate from fructose-6-phophate and UDP-glucose; invertase catalyzes the breakdown of sucrose to glucose and fructose; and UGPase produces UDP-glucose from UTP and glucose-1-phosphate. Plants were transformed with each gene independently under the regulatory control of two different promoters: the over-expressing constitutive 2 35S promoter and the vascular (xylem) specific 4CL promoter. This research demonstrates altered carbon partitioning by over-expression these key genes which influences carbohydrate metabolism and consequently, fibre development and yield.