P0738 Unraveling Two Ways of Lignin Biosynthesis in Sugarcane Culm: An Overview of Transcriptional Regulation

Michael dos Santos Brito , Plant Biology Dept. - IB-UNICAMP , Ribeirao Preto, Brazil
Paula M Nobile , UNICAMP, Campinas, Brazil
Alexandra Bottcher , UNICAMP, Campinas, Brazil
Jullyana C.M.S. Moura , UNICAMP, Campinas, Brazil
Silvana Aparecida Creste Dias de Souza , Centro de Cana - Instituto Agronômico, Ribeirão Preto, Brazil
Renato Vicentini , UNICAMP, Campinas, Brazil
Adriana B. Santos , UNICAMP, Campinas, Brazil
Juliana L.S. Mayer , UNICAMP, Campinas, Brazil
Pedro Araújo , UNICAMP, Campinas, Brazil
Ivan A. Anjos , Centro de Cana - Instituto Agronômico, Ribeirão Preto, Brazil
Mauro Alexandre Xavier , Instituto Agronomico - Centro de Cana, Ribeirão Preto, Brazil
Marcos G. A. Landell , Centro de Cana - Instituto Agronômico, Ribeirão Preto, Brazil
Michel Vincentz , LAGEP-CBMEG -State University of Campinas -UNICAMP, Campinas, Sao Paulo, Brazil
Paulo Mazzafera , UNICAMP, Campinas, Brazil
Cell wall recalcitrance is the main bottleneck for an effective production of lignocellulosic ethanol, in part due to lignin. Recently, transcription factors (TFs) have been suggested as better targets for cell wall modification instead lignin biosynthesis-related genes. Here we studied two contrasting sugarcane genotypes for lignin content/composition (thioacidolysis, acid-soluble and insoluble Klason, ratio S/G by GC/MS) and TFs expression. As a strategy to survey contrasts among tissues, from the top to the base the culm was divided in immature, intermediary and mature internodes, and these were divided in pith and rind. Lignin increased from the top to the base and the highest content was found in the rind. S/G ratio was also different in these tissues in both genotypes, indicating a suitable model to study lignin composition/deposition in sugarcane. Quantitative PCR analyses of 11 TFs showed that 9 (ScMYB26, ScVND6/7, ScNST1-2-3, ScMYB46, ScMYB83, ScMYB85, ScVNI2, ScKNAT7 and ScMYB61) were positively correlated with lignin content, while ScMYB52/54 and ScMYB58 had a negative correlation. Except ScMYB52/54 and ScMYB58, all TFs were more expressed in the rind. High ScMYB58 expression showed a positive correlation with high S/G ratio. A Pearson correlation analysis indicated a possible interaction between ScMYB58 and ScF5H (enzyme related to S monomer synthesis). These findings suggest that different lignin deposition between rind and pith might be under transcriptional regulation. Yeast-One-Hybrid assays are in progress in order to reveal new TFs involved with transcriptional regulation of lignin biosynthesis.