Efficient Regeneration of the Eucommia ulmoides Oliver Plant from Hypocotyl Explant

Abstract

A rapid and efficient method for the regeneration of Eucommia ulmoides Oliver, a rare Tertiary species surviving only in China, has been developed. Hypocotyl segments exscinded from 2 -week-old seedlings were chosen as explants. Multiple shoot buds were more significantly induced on medium containing MS basal medium supplemented with 10 μM BAP alone than on other media. The addition of NAA resulted in callus enlargement, but it did not promote the production of multiple shoot buds. However, the adventitious shoots became cirrhotic and stunted after subculturing on an identical medium supplemented with BAP alone. It was found that the addition of 10 μM GA3 to the medium was the most suitable for the stimulation of shoot elongation and further growth. Shoots longer than 2 cm cultured on the medium supplemented with 0.5 μM NAA and 0.1 μM ABA were highly responsive and produced the maximum number of roots per shoot. Regenerated plantlets with expanded leaves and well-developed roots could be successfully transferred to a pot containing vermiculite for acclimatization and then to a greenhouse. The regeneration protocol developed in this study provides the basis for E. ulmoides germplasm conservation, rapid propagation, and further genetic alteration for medicinal compound and EU-rubber production.