Multiplication of RubusGermplasm In Vitro:A Screen of 256 Accessions

Abstract

Rubusgermplasm at the National Clonal Germplasm Repository, Corvallis, Oregon, was screened to determine tissue culture growth media suitable to the diverse collection being maintained. Explants were taken from mature pot-grown plants. Murashige and Skoog (MS) medium with 1 mg/l benzyladenine (BA) and 0.1 mg/l indole butyric acid (IBA) was used for initiation (explant establishment) of 256 different accessions of Rubus.Evaluation was based on a three fold (3X) increase in the number of plantlets following three weeks on the medium. Following two initial transfers, those which did not multiply 3X in three weeks were divided into two groups based on the vigor of the clone. Group 1 (low multiplication but growing well) were placed on MS with 1 mg/l BA, 0.1 mg/IBA and 0.1 mg/l GA ₃while Group 2 (low multiplication and poor growth) were grown on Anderson's medium with 1 mg/l BA and 0.1 mg/l IBA. Accessions which did not respond with 3X growth after two transfers of three weeks each were placed on media with additional modifications. The majority (62%) will multiply 3X in three weeks on MS medium with 1 mg/l BA, 0.1 mg/l IBA and 0.1 mg/l GA ₃while another 18% respond on Anderson's medium at the same hormone levels. The remaining 20% require BA at 2 mg/l, 0.1/mg/l IBA and GA ₃0.1 mg/l to produce 3X growth in three weeks. This is the first report of the in vitroculture of many of these Rubusspecies and cultivars. Chemical names used: N(-phenylmethyl)-1H-purin-6-amine (BA); Indole-3-butyic acid (IBA); Gibberellic Acid A ₃(GA ₃).