Identification and Characterization of a Cinnamyl Alcohol Dehydrogenase gene (TgCAD1) in Teak (Tectona grandis L. f)

Teak (Tectona grandis L.f), tropical tree native to Southeast Asia, has worldwide reputation as the most durable timber with more than two million hectares, of which 50.000 ha are cultivated in Brazil. Teak is currently a favorite choice for agro-forestry and wood market due to its high wood qualities and properties. There is little research on molecular characterization of tropical forest species; gene characterization studies are absent in teak. Cinnamyl alcohol dehydrogenase (CAD) gene, involved in the phenylpropanoids metabolism has important roles in wood formation in vascular plants, working directly in the monolignols synthesis, sub-components of lignin. Therefore, the objective of this research is to identify and characterize CAD genes in Tectona grandis tissues. Subsequently, it was researched conserved domains related to functions of interest and used to design degenerate primers, using model species as reference. Translation of PCR sequencing showed "Alcohol dehydrogenase GroES-Like” and “Zinc -binding dehydrogenase” conserved domains. The 1489 bp fragment named here TgCAD1 is phylogenetically related to AtCAD1 and PtCAD12, from Arabidopsis and Populus respectively. It was established the overall TgCAD1 3D crystal structural modeling. Additionally, total RNA extraction and cDNA synthesis were performed from xylem, branches and leaves of 12 and 60 year old Brazilian populations, for expression analysis via Real Time RT-PCR, as well as determining 3’-5’ TgCAD1 extremes by RACE methodology. The understanding of how lignin coupling appears to be essential for future studies involving tree lignin content manipulation of commercial interest via genetic transformation. This research will encourage genome-wide discovery of novel teak genes and genome sequencing.