Abstract
Sugarcane (Saccharum spp.) is a monocot with C4 metabolism with high sucrose accumulation in the stem. It is an important tropical crop, grown for sugar production and, more recently, for biofuel ethanol production, among other products. Despite its economic importance, little is known about the structure of its genome. It is known that modern cultivars are interspecific hybrids with a polyploid genome. The program SUCEST (Sugarcane EST Project - Vettore et al., 2003) produced transcriptome sequences of this plant in order to start the study of coding regions. From the database SUCEST, two SAS (Sugarcane Assembled Sequences), called sc-thi1 and sc-thi1, were identified as putative homologous to the thi1 gene of Arabdopsis thaliana and the THI4 gene of Saccharomices cerevisiae. These genes are involved in the biosynthesis of the thiazole ring, a component of thiamine (vitamin B1). This vitamin is needed for cell function, as it is co-factor for enzymes that act in several different metabolic pathways (glycolysis, the citric acid cycle and the pentose phosphate cycle). While in A. thaliana and other plant species there is only one copy of this gene, Saccharum has at least two copies, like other C4 grasses. Previous results from our group showed that an A. thaliana tz-201 mutant accumulated sucrose in tissues. This, combined with the presence of two transcripts with distinct expression profiles in SUCEST, makes it interesting to study the function of the sugarcane homologues. Thus, this project aims to study the thi1 genomic context and the protein THI1 function in C4 metabolism, specifically in sugarcane. (AU)
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