Rooting and acclimatization of in vitro plantlets of mtl-D gene modified Robinia pseudoacacia ‘Idaho’

Robinia pseudoacacia ‘Idaho’ (Robinia×ambigua ‘Idahoensis’, R. pseudoacacia×R. viscosa) modified by a mtl-D gene went through five lines and had characteristics of drought tolerance. Three stages of their micropropagation had been studied by previous investigators. The other two stages, in vitro shoot rooting and plantlet acclimatization, still remained unsolved in the laboratory. For this paper, we studied the later two stages based on the previous achievements. Results showed that the highest rooting rate of Idaho locust was 98.4% when the in vitro shoots, over 2.5 cm in height and 0.08 cm in diameter, were placed on a half strength MS basal medium with 0.4 mg·L^-1 IBA and 0.1 mg·L^-1 NAA as supplements and were solidified with 0.5% agar; the highest survival rate was 98.3% when the rooted plantlets were potted in vermiculite. All the stages for micropropagation of the Idaho locust, modified by the mtl-D gene, were assembled completely. The tissue culture plants grow well in the field.