Investigations on biotechnologically developed poplar clones as raw material for pulp and paper industry

Abstract

In this review an overview of our research on biotechnologically developed poplar clones for application in paper and pulp industry was presented. Nine native clones of Populus tremula as well as five hybrid clones of P. deltoides x P. deltoides were used for establishment of plant tissue culture system. For this purpose 'Woody Plant Medium' (WPM), supplemented with 1 mg/l zeatine (WPMZ) and WPM supplemented with 0.5 mg/l indole-3-butyric acid (IBA) (WPMB), were used for shoot and root regeneration, respectively. Established tissue cultures of poplar clones offer the potential for manipulation with enzymes involved in the lignin biosynthetic pathway such as caffeic acid O-methyltransferase and lignin peroxidases. Poplar clones (89M011, 89M066, Dursunbey 2) with the highest shoot regeneration efficiencies (70-100 %) were used for Agrobacterium transformation with antisense caffeic acid O-methyltransferase (pOMT8) and cationic peroxidase (Shpx6a) genes. Tobacco (Nicotiana tabacum) was used as a model control system. Constructs used in the study were obtained from forage legume Stylosanthes humilis and showed a high homology to corresponding caffeic acid O-methyltransferase (COMT) and peroxidase genes of poplar. Our results showed that antisense pOMT8 and Shpx6a peroxidase genes down regulated the activity of related enzymes. In the pOMT8 transgenics composition of lignin was changed, without changes in amount of lignin. However, in Shpx6a transgenics decreases in amount of lignin (up to 20 %) was observed. In the tobacco experiments with two types of transgenes (pOMT8 and Shpx6a) reduction of related enzymes activities and reduction of lignin amount was occurred in several transgenic plants.