Maintenance of the induced hypomethylated state of tobacco nuclear repetitive DNA sequences in the course of protoplast and plant regeneration

adn cal callo callus cultivo de tejidos culture de tissu dna dns gewebekultur kallus methylation methylierung nicotiana nicotiana tabacum nucleotide sequence nucleotidsequenz organogenese organogenesis protoplast protoplaste protoplastos protoplasts secuencia nucleica tissue culture