Reverse-cleft in vitro micrografting of Ziziphus jujuba Mill. Infected with jujube witches’ broom (JWB)

Jujube witches’ broom (JWB) is a destructive disease, caused by a phytoplasma, of Chinese jujube ( Ziziphus jujuba Mill.), an important traditional fruit in China and South Korea. Micrografting of plantlets to detect those affected with JWB is difficult due to differences in stem diameter between the scion and rootstock. In this study, an in vitro micrografting technique, reverse-cleft graft, suitable for rootstock thinner than scion was developed and optimized. The JWB phytoplasma was successfully transmitted into the scion from diseased rootstock using this technique as determined by polymerase chain reaction. Micrografted plantlets of Chinese jujube were incubated on Murashige and Skoog medium without plant growth regulators. The survival frequencies of 78–91%, depending on grafting combinations, were obtained.