Lignin in species of the genus Saccharum

Abstract

The increase in world consumption of finite fossil fuel resources and the negative climate consequences of their use are currently driving the search for alternative energy sources such as biomass, which is mainly composed of cellulose, hemicellulose and lignin. The biomass can be used as a feedstock for renewable energy production and it can be transformed into biofuels through a process called saccharification. Lignin is a complex aromatic polymer, essential for plant growth and development, but at same time inhibiting the saccharification for a number of reasons. Therefore, an understanding of the processes that govern the recalcitrance of cell wall generated by lignin is urgent in order to fully explore the potential of cellulosic biofuels. Since the lignin biosynthetic pathway is relatively conserved among different species the knowledge obtained for dicots studies can be applied to monocotyledonous with potential characteristics for second generation bioethanol production. The sugar cane, C4 plant, is one of the most efficient in collecting and converting sunlight into chemical energy, with a high content of sucrose. Recently, with the advent of the development of second generation bioethanol technology, there has been interest in the study for the development of a type of sugarcane with an improved quality of biomass (less recalcitrance and higher fiber content and cellulose) for use in bioethanol production from lignocellulosic, or derived from the cell wall components. This research proposes to study the ancestral genotypes of current commercial varieties of sugar cane: Saccharum officinarum, Saccharum barberi, Saccharum robustum and Saccharum spontaneum, evaluating the content and type of lignin, the identification and expression of genes related to the biosynthesis of this polymer, as will also be made chemical characterization of the cell wall in these species. The results of this research will advance our understanding and use of the genetic diversity of the genus Saccharum with regard to second-generation bioethanol production, and may help breeding programs and classic genetic transformation to develop commercial varieties (hybrids) cane with features important for bioenergy. (AU)