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Article|18 Jan 2022|OPEN
Phytoplasma effector Zaofeng6 induces shoot proliferation by decreasing the expression of ZjTCP7 in Ziziphus jujuba
Peng Chen2 ,† , Lichuan Chen2 ,† , Xia Ye1 , Bin Tan1 , Xianbo Zheng1 , Jun Cheng1 , Wei Wang1 , Qiqi Yang2 , Yu Zhang2 , Jidong Li2 , and Jiancan Feng,1,2 ,
1College of Horticulture, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China
2College of Forestry, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China
*Corresponding author. E-mail: lijidong@henau.edu.cn,jcfeng@henau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhab032 (2022)
doi: https://doi.org/10.1093/hr/uhab032
Views: 241

Received: 08 Jan 2021
Revised: 10 Oct 2021
Accepted: 15 Oct 2021
Published online: 18 Jan 2022

Abstract

The jujube witches’ broom (JWB) phytoplasma is associated with witches’ broom, dwarfism, and smaller leaves in jujube, resulting in yield losses. In this study, eight putative JWB effector proteins were identified from potential mobile units of the JWB genome. Among them, Zaofeng6 induced witches’ broom symptoms in Arabidopsis and jujube. Zaofeng6-overexpressing Arabidopsis and unrooted jujube transformants displayed witches’ broom-like shoot proliferation. Transient expression of Zaofeng6 induced hypersensitive response like cell death and expression of hypersensitive response marker genes, like harpin-induced gene 1 (H1N1), and the pathogenesis-related genes PR1PR2, and PR3 in transformed Nicotiana benthamiana leaves, suggesting that Zaofeng6 could be a virulence effector. Yeast two-hybrid library screening and bimolecular fluorescence complementation confirmed that Zaofeng6 interacts with ZjTCP7 through its first two α-helix domains in the cell nuclei. ZjTCP7 mRNA and protein abundance decreased in Zaofeng6 transgenic jujube seedlings. The expression of some genes in the strigolactone signaling pathway (ZjCCD7ZjCCD8, and CYP711A1) were down-regulated in jujube shoots overexpressing Zaofeng6 and in zjtcp7 CRISPR/Cas9 mutants. Zaofeng6 induces shoot proliferation through decreased expression of ZjTCP7 at the transcriptional and translational levels.