Isolation and characterization of lignin biosynthetic pathway genes in leucaena leucocephala

Abstract

World wide annual production of paper has increased more than three fold in the past forty years, amounting to a total production of 120 x 106 tons. In India the annual production of paper is close to 5 million tons. India’s annual soft woods and pulp imports are worth rupees ten thousand crores and the projected annual short fall of paper and paper products is expected to grow to approximately 4 million MT by the year 2010. In addition, the growth of paper and paper products consumption in India is expected to be the highest in Asia during the current decade. Thus, it has become imperative to achieve self sufficiency in paper and pulp production, which may be achieved with the development of fast growing trees providing higher biomass with low lignin content per unit of land. Wood, agricultural residues and many other plant materials which can be used for pulp and paper production consist largely of lignocellulose (a composite of mainly cellulose, hemicellulose and lignin). In the production of paper pulp (which is mainly cellulose), the hemicellulose and much of the lignin is removed using alkali. To produce bright paper, pulp may require a further bleaching treatment to remove lignin residues. This delignification process consumes large quantities of energy and hazardous chemicals. Reducing the content or changing the quality of lignin in pulp wood species without compromising the mechanical strength of the plant is desirable for paper industry. This would be beneficial both from the economical as well as environmental point of view. The results could be extrapolated to the forage crops to improve digestibility since the presence of lignin limits the ability of microorganisms to break down the cellulose and hemicellulose.