Differentiation of Sugarcane Cultivars for Green Energy Using Microscopy and Tissue Culture

As mankind has become increasingly dependent on fossil fuel, a finite resource, significant progress has been made in developing favorable alternative methods of energy production. Sugarcane (Saccharum sp.) is, because of its competitiveness, a potential natural resource. By applying biotechnology to quality sugarcane varieties it is possible to develop a new array of plants with high added value including sugarcane by-products, such as fiber and wood. This research may serve as an aid in exploring novel approaches, based on structural (cell wall, epidermic, subepidermic and vascular bundles constitution) and physiological (plantlet growth rate) criteria for practical methodologies in order to select new sugarcane varieties that are not attainable by conventional tissue culture methods. The histologic analysis performed on Mex 70-485, Mex 69-290 and B 43-337 sugarcane cultivars which have been classified as having low, medium and high fiber content, respectively, allowed us to demonstrate that their fiber content is directly related to: 1) the mean number of rows of thick-wall cells that constituted the vascular bundles: 4.68, 5.68 and 7.92 in the varieties Mex 70-485, Mex 69-290 and B 43-337 respectively. The mean diameter of these vascular bundles were, in the same order: 299, 355 and 333 mm. 2) the number of epidermal and sub-epidermal layers of thick-wall cells of these varieties: Mex 70-485 showed one, Mex 69-290 two and B 43-337 had up to four layers. We did not find differences among these varieties regarding: 1) the thickness of the walls of cells forming the vascular bundles, which varied between 1.90 and 2.11 mm, and 2) the number of vascular bundles per unit area observed under light microscopy. Callus cultures established from the leaf tissue of these varieties did not show morphological differences. Plantlets regenerated from calluses from the Mex 69-290 variety grew twice as fast as the other two in the same incubation period. This finding is in agreement with the precocity of Mex 69-290 in the field.