In vitro propagation of persimmon (Diospyros kaki Thunb.)

Persimmon (Diospyros kaki Thunb.) is a temperate fruit tree species diffused in all continents. The traditional propagation method adopted by the nursery industry is based on budding/grafting scion cultivars on seedlings from D. kaki, Diospyros lotus, and Diospyros virginiana, the most important species used as rootstock, reproduced by seeds since they are not easy to root. Furthermore, most of nonastringent cultivars of persimmon are not compatible with D. lotus, a rootstock largely utilized because of its hardiness and frost resistance. The main in vitro tissue culture techniques, developed for persimmon, deal with direct regeneration (from dormant buds and root tips), and indirect regeneration through callus from dormant buds, apexes, and leaves. The bottlenecks of micropropagation are (1) the recalcitrance of many cultivars to in vitro establishment, (2) the low multiplication ratio of D. kaki compared to other fruit tree species, (3) the very low rooting ability of ex novo microcuttings both from direct and indirect regeneration, (4) the high sensitivity to transplant from in vitro to in vivo conditions. The development of reliable in vitro regeneration procedures is likely to play a key role for production of both clonal rootstocks and self-rooted cultivars. The general protocol for micropropagation of persimmon reported here is based on the establishment of winter dormant buds in vitro, shoot development, multiplication and elongation, and shoot rooting, using cytokinins (BA or zeatin) in a MS media along with an auxinic pretreatment for rooting induction.