Adventitious shoot regeneration from leaves of apple rootstock ‘Pingyitiancha’ (Malus hupehensis var. pinyiensis) and genetic fidelity of regenerated plantlets using SSR markers

Abstract

Apple is one of the major fruit tree species in China, its cultivation area and total output rank first in the world. ‘Pingyitiancha’ (Malus hupehensis var. pinyiensis) is a widely used rootstock for apple cultivation in China. Several factors affecting leaf regeneration were investigated. In this study, a successful adventitious shoot regeneration protocol for this cultivar was established. ‘Pingyitiancha’ leaves were a suitable source of explants for regeneration of adventitious shoots. The optimal adventitious shoot regeneration protocol involved subculturing seedling leaves for 30-35 d. The optimum medium was Murashige and Skoog (MS) medium containing 2.0 mg L-1 thidiazuron and 0.2 mg L-1 indole-3-butyric acid. Explants with the abaxial surface in contact with the medium kept for 14 d in the dark showed the highest regeneration percentage of adventitious shoots of explants (100%), and produced an average of 3.6 shoots per regenerating explant. Shoots regenerated from leaves were rooted on half-strength MS medium containing 0.4 mg L-1 1-naphthalene acetic acid. The rooting percentage was 94.4%. Using SSR markers, all banding profiles from regenerated plantlets were monomorphic and same to those of the mother plant. It showed that the uniformity of the in vitro regenerated plantlets was maintained.