Henan Agricultural University researchers review on jujube witches’ broom, fruit tree disease associated with phytoplasma

A review in Fruit Research by researchers from Henan Agricultural University, China, explore the state of art of research on jujube witches’ broom (‘Zaofeng’) disease, a fruit tree disease associated with phytoplasma.

Phytoplasmas are insect-transmitted bacteria pathogen associated with more than 1000 plant diseases worldwide. Phytoplasma infected plants exhibit extensive architectural changes, stop reproducing, and appear to serve solely as habitats for the phytoplasma pathogens and their insect vectors.

The fruit jujube (Ziziphus jujuba), also called ‘Zao’ in Mandarin Chinese, has a long cultivation history of more than 7000 years and grows in more than 40 countries. Jujube Witches’ Broom (JWB) disease, referred to ‘Zaofeng’ disease in Chinese, is related to the presence of JWB phytoplasma (Candidatus phytoplasma ziziphi), a 16SrV-B phytoplasma subgroup member. JWB phytoplasma-infected jujube trees show altered fundamental plant development processes. In Chinese, ‘feng’ means crazy or uncontrolled, illustrating the witches’ broom symptoms of shoot proliferation and leafy flowers.

JWB disease resulting in yield loss, decreased fruit quality, the tree die gradually within a few years, bringing heavy losses to the jujube industry.

This article reviews the research history, symptomatology, aetiology and epidemiology of JWB disease, and stress the pathogenesis study of JWB.

 At the physiological and biochemical level, changes occur in the photosynthesis, anatomical structure, mineral elements, and endogenous hormone content of plants after infection of JWB phytoplasma. At the molecular level, high-throughput sequencing techniques such as transcriptome and proteome analysis reveal multiple genes and metabolic pathways related to the plant-pathogen interaction. The genome of JWB phytoplasma ‘nky’ strain has been sequenced and consist of 750,803 bp within one circular chromosome that encodes 694 protein-coding genes. Virulence effector proteins such as SJP1, SJP2, SJP3, and Zaofeng6 were identified, and studied for their function during the symptom induction. In addition, the article also reviews the research progress in the detection and prevention of JWB disease, and looks forward to the further research focus.

Explain the interaction mechanism between phytoplasma effectors and plant target proteins is the key for JWB disease study. By combining molecular biology methods with traditional phytopathology techniques, we could achieve effective prevention and cure these “crazy” plants.  

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References

Authors

Sicheng Guo, Liyuan Gu, Yajie Zhang, Yingxia Wu, Bin Tan, Xianbo Zheng, Xia Ye, Jun Cheng, Wei Wang, Shuwen Bi, Zesen Qiao, Yujing Huang, Peng Chen, Jidong Li, Jiancan Feng

Affiliations

Henan Agricultural University

About Jidong Li & Jiancan Feng

Jidong Li, professor of Henan Agricultural University

Jiancan Feng, professor of Henan Agricultural University