CBN-V Video Archives - S7-19
Optimizing Plant Regeneration from Friable Embryogenic Callus using Temporary Immersion Systems

Montoya J.E.¹, R. Escobar¹, P. Chavarriaga¹, J. Tohme¹ and W.M. Roca²

1. Biotechnology Research Unit, International Center for Tropical Agriculture –CIAT A.A. 6713 Cali, Colombia p.chavarriaga@cgiar.org
2. CIP, Apartado 1558, Lima, Peru

        In order to improve embryo-to-plant conversion from friable embryogenic callus (FEC) of commercial cassava cultivars [TMS-60444 (MNig11), MCol2215 (Venezolana) and CM3306-4 (Ica Negrita)], we are combining RITA® with standard culture methods on solid media. Plants are usually regenerated from FEC after several cycles on liquid and/or solid media. FEC proliferates in liquid SH with picloram. Plating FEC on solid Greshoff and Doy (GD) basal medium with picloram is necessary for FEC purification. For embryo differentiation/maturation (greening), FEC must be transferred to solid GD with NAA and/or BAP. Murashige and Skoog (MS) basal medium supplemented with activated charcoal eliminates excess of hormones. Finally transfer to MS with gibberellic acid promotes embryo elongation and plantlet development. An extra rooting medium (17N) may be necessary before taking plants to the greenhouse. Permanent contact with the liquid/solid media may reduce the efficiency of plant regeneration, which is actually very low considering the number of plants that could develop from the thousands of embryos in the suspensions. We are testing RITA® at different immersion cycles (6, 8 and 12 hours) for embryo development and maturation (i.e. after activated charcoal; for NAA or BAP treatment). Preliminary results with TMS60444 show that, even with very old suspensions, normal-looking plants are still recovered at substantially higher rates.

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