Molecular cloning of korrigan and sucrose synthase genes and genetic transformation of eucalyptus for cellulose enhancement

Abstract

Eucalyptus (Family: Myrtaceace) is among the fastest growing woody plant in the world and comprises of nearly 700 species distributed throughout the world. It is grown world wide due to its wide adaptability, extremely fast growing nature and most importantly excellent wood and fiber properties which make it an important source of raw material for pulp and paper industry. Cellulose, the most abundant biopolymer on earth, consists of crystalline assemblies of parallel 1,4-and#61538; linked glucan chains. Current models envision plant cellulose biosynthesis to be a three step process: (1) plasma membrane-associated sucrose synthase (SUS) which directly channel the UDP-glucose substrate to cellulose synthesizing machinery (2) coordinately expressed multiple cellulose synthase genes, organized in the form of hexagonal rosettes, polymerize glucose monomers into glucan chains while recycling liberated UDP back to SUS and (3) a membrane-associated cellulase (and#61538;-1,4 glucanase; korrigan (KOR), acts as an editor of newly produced glucan chains. These two genes (namely KOR and SUS) could be important target for up regulation of the cellulose content in wood. Thus, there is a possibility for improvement of selected clones of Eucalyptus for up-regulation of cellulose content through plant genetic manipulation using these genes. Plants of elite clone (self pruning and higher biomass productivity) of E. tereticornis growing at Thapar University Campus were selected for the present study. Cultures were established from nodal explants taken from freshly coppiced shoots of elite plant of E. tereticornis (10 years old). Cultures were initiated on MS medium supplemented with 2.5 and#956;M BA and 0.5 and#956;M NAA. Maximum numbers of shoots per culture vessel (342) were obtained on MS supplemented with 2.5 and#956;M BA in combination with 0.5 and#956;M NAA, whereas shoot elongation was achieved on MS medium supplemented with 0.1 and#956;M BA 164 and 0.5 and#956;M NAA.