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

Abstract

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.

Genetic Improvement of Chinese Jujube for Disease Resistances: Status, Knowledge Gaps and Research Needs

“…Jujube witches' broom (JWB), associated with phytoplasma presence, is an extremely destructive disease commonly found in both North and South China [15], as well as in India [16], Korea [17,18] and Japan [19]. This important and damaging disease has caused yield reductions ranging from 10% to 80% [20,21].…”

“…JWB phytoplasmas have been identified solely from jujube trees, which suggested that the feeding preferences of H. sellatus, rather than the resistance of other potential plant hosts may be responsible for this specificity [18]. JWB is the only jujube disease for which breeding efforts have been systematically employed and significant progress has been made [15,28]. Most of the reported breeding activities were carried out in Hebei, China, where JWB has been prevalent [15,28,29].…”

“…JWB is the only jujube disease for which breeding efforts have been systematically employed and significant progress has been made [15,28]. Most of the reported breeding activities were carried out in Hebei, China, where JWB has been prevalent [15,28,29]. Resistance was first evaluated in jujube germplasm collections using field resistance as the primary evaluation criteria.…”

“…A five-grade rating system was applied in the experiment. A large variation of JWB resistance was found in the jujube germplasm evaluated, ranging from highly susceptible to highly resistant [15]. After five years of repeated observations, four resistant clones (T15, J2, J5 and J8) were selected.…”

Genome-Wide Identification and Analysis of MicroRNAs Involved in Witches’-Broom Phytoplasma Response in Ziziphus jujuba

“…It is caused by phytoplasmas which are bacteria without cell walls that were first discovered in the phloem of plants in 1967 by Yoji Doi and co-workers [5]. Phytoplasmas are transmitted by phloem-sucking leafhoppers and Chinese Jujube plants infected with phytoplasmas display a variety of symptoms, such as small leaves, yellowing, witches’-broom, phyllody, stunting, sterile flowers and finally death after a few years of infection [6, 7]. Phytoplasmas are very destructive agricultural pathogens, and have devastating effects on over 1000 plant species worldwide [8, 9].…”