AN IN VITRO PROPAGATION AND REGENERATION SYSTEM FOR RUBUS GERMPLASM

A propagation system for in vitro establishment and multiplication of Rubus idaeus L. germplasm as the first step to set up a backup in vitro collection is reported here. Explants were taken from field mature plants growing in IASMA’s (Istituto Agrario San Michele all’Adige Research and Innovation Centre) field germplasm collection. Modified Murashige and Skoog (MS) and Quoirin & Lepoivre (QL) mediums with and without 0.6 mg.L^-1 6-benzylaminopurine (BA) were used for initiation. Multiplication of developed micro shoots was carried out on both media with BA at 0.6 mg.L^-1. Initial development and growth was highly depending on the cultivar, survival rates on BA supplemented modified MS varied from 10 to 100%. QL basal medium was not suitable for raspberry initiation. BA was effective in the promotion of shoot development across the wide range of genotypes. Results obtained after three subcultures showed that for both treatments the multiplication rate decreased significantly from the first to the second subculture and then stabilized reaching for all the accessions an average multiplication factor of 3-4 on both basal mediums. Shoot tips were rooted in vitro using IBA (Indol-3-butyric acid) or IAA (Indol-3-acetic acid) at different concentrations. The highest rooting percentage (87%), number of roots per shoot and length of primary roots was obtained when 0.2 mg.L^-1 of IBA was added to one-fourth strength MS basal medium. After acclimation of the rooted plants an average survival of 95% was achieved.