Involvement of DNA methylation in tree development and micropropagation - Valledor, Luis; Hasbún, Rodrigo; Meijón, Mónica; Rodríguez, Jose Luis; Santamaría, Estrella; Viejo, Marcos; Berdasco, María; Feito, Isabel; Fraga, Mario F.; Cañal, María Jesús; Rodríguez, Roberto