Effect of plant growth regulators on plant regeneration of Dioscorea remotiflora (Kunth) through nodal explants

Dioscorea remotiflora (Kunth) is an important wild plant that produces tuberous roots used as a source of food in the Western part of Mexico. Lack of planting material and inefficiency of traditional methods of propagation are the main constraints for implementing large-scale cultivation. In contrast, tissue culture techniques allow increasing multiplication and rapid production of plant material. In this regard, leaves or nodal segments were incubated on MS, B5 and WPM culture media with different PGRs in order to obtain an efficient micropropagation protocol. Leaves explants were unable to inducing shoots or callus. However, nodal segments produced axillary shoots and/or callus in all culture media. MS containing 2.33 mu M KIN was the most suitable to inducing shoots; an average of 6.6 shoots per segment for 100 % explants was obtained, which displayed also the greater number of nodes (5.0) and leaves (7.9) per segment. A decrease on shoot proliferation was observed combining BA or KIN with 2,4-D or NAA. However, small brownish callus were induced on 100 % of segments using 2.33 mu M KIN with 5.37 mu M 2,4-D or 9.30 mu M KIN plus 2.69 mu M NAA. In contrast, by adding 2.69 mu M NAA, 66.4 % of the nodal segments formed shoots and produced also yellowish friable callus on the base of the shoots. Shoots were easily rooted with 8.28 mu M IBA (96.9 %), displaying the greatest root and shoot biomass, but maximum number of tuberous roots, and root or tuberous root biomass was produced increasing IBA (20.7 mu M).