BIANNUALREPORT2012-2013

Group Structure

Group Leader: David Caparros Ruiz (CRAG Researcher)
Researchers: Joan Rigau Lloveras
Postdoctoral Researchers: Silvia Fornalé, Pedro Fernández.
PhD: Jorge Enrique Salazar.
Undergrad or Master Students: Eric López Olalla (2012), Borja Garnelo Gómez (2013), Africa Sanchiz Giraldo (2013).

Summary

Maize is one the most important crops worldwide essentially committed to animal feeding purposes. In many cases, the maize lignocellulosic biomass represents an agricultural waste due to the presence of the recalcitrant lignin polymer in the cell walls. Thus, lignin polymer is negatively associated with the nutritional (forage) and most recently the energetic (cellulosic bioethanol) values of the maize lignocellulosic biomass. Modifying lignin content and/or composition could lead to the production of new varieties with increased values for the forage and energetic industries.

Monolignols, the structural components of the lignin polymer, are synthesized through the phenylpropanoid pathway. We have produced maize transgenic plants down-regulated for Cinnamyl alcohol Dehydrogenase (CAD-RNAi), the enzyme involved in the last enzymatic step of the monolignol biosynthesis. Cellulosic bioethanol production from field-grown CAD-RNAi plants demonstrated that a relevant increase in the energetic value of the transgenic biomass can be achieved without compromising maize growth and development.

We have also initiated the study of the effect of the down-regulation of other enzymes of the lignin pathway through the characterization of mutants or transgenic plants. In parallel, we have characterized R2R3-MYB transcription factors regulating lignin biosynthesis in maize. Thus, we produced transgenic plants overexpressing these factors under the control of the CAD gene promoter. The characterization of these lines is underway.

Research Projects

• Functional characterization of lignin genes in maize.
• Identification and characterization of transcription factors controlling lignin biosynthesis.

Selected Publications

Fornale S., Capellades M., Encina A., Wang K., Irar S., Lapierre C., Ruel K., Joseleau J.-P., Berenguer J., Puigdomenech P., Rigau J., Caparros-Ruiz D.
Altered lignin biosynthesis improves cellulosic bioethanol production in transgenic maize plants down-regulated for cinnamyl alcohol dehydrogenase
(2012) Molecular Plant, vol. 5 (4), pp. 817-830

Gray J., Caparros-Ruiz D., Grotewold E.
Grass phenylpropanoids: Regulate before using!
(2012) Plant Science, vol. 184, pp. 112-120