title: Transgenic citrus expressing synthesized cecropin B genes in the phloem exhibits decreased susceptibility to Huanglongbing.
abstract: Expression of synthesized cecropin B genes in the citrus phloem, where Candidatus Liberibacter asiaticus resides, significantly decreased host susceptibility to Huanglongbing. Huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus bacteria, is the most destructive disease of citrus worldwide. All of the commercial sweet orange cultivars lack resistance to this disease. The cationic lytic peptide cecropin B, isolated from the Chinese tasar moth (Antheraea pernyi), has been shown to effectively eliminate bacteria. In this study, we demonstrated that transgenic citrus (Citrus sinensis Osbeck) expressing the cecropin B gene specifically in the phloem had a decreased susceptibility to HLB. Three plant codon-optimized synthetic cecropin B genes, which were designed to secrete the cecropin B peptide into three specific sites, the extracellular space, the cytoplasm, and the endoplasmic reticulum, were constructed. Under the control of the selected phloem-specific promoter GRP1.8, these constructs were transferred into the citrus genome. All of the cecropin B genes were efficiently expressed in the phloem of transgenic plants. Over more than a year of evaluation, the transgenic lines exhibited reduced disease severity. Bacterial populations in transgenic lines were significantly lower than in the controls. Two lines, in which bacterial populations were significantly lower than in others, showed no visible symptoms. Thus, we demonstrated the potential application of the phloem-specific expression of an antimicrobial peptide gene to protect citrus plants from HLB.
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China. zouxiuping@cric.cn.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China. zouxiuping@cric.cn.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Zou
authors.affiliation: Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.|Guangan Agricultural Bureau, Chongqing, 400716, People's Republic of China.
authors.forename: Xueyou
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.
authors.forename: Lanzhen
authors.initials: L
authors.lastname: Xu
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.
authors.forename: Tiangang
authors.initials: T
authors.lastname: Lei
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.
authors.forename: Aihong
authors.initials: A
authors.lastname: Peng
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.
authors.forename: Yongrui
authors.initials: Y
authors.lastname: He
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China.
authors.forename: Lixiao
authors.initials: L
authors.lastname: Yao
authors.affiliation: Citrus Research Institute, Chinese Academy of Agricultural Sciences/National Center for Citrus Variety Improvement, Chongqing, 400712, People's Republic of China. chenshanchun@cric.cn.|Citrus Research Institute, Southwest University, Chongqing, 400716, People's Republic of China. chenshanchun@cric.cn.
authors.forename: Shanchun
authors.initials: S
authors.lastname: Chen
mesh_terms: D000818:Animals; D015153:Blotting, Western; D032084:Citrus sinensis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D060467:Disease Resistance / Q000235:genetics; D015870:Gene Expression; D054884:Host-Pathogen Interactions; D007150:Immunohistochemistry; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D009036:Moths / Q000235:genetics; D052585:Phloem / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012230:Rhizobiaceae / Q000502:physiology
chemical_list: D019476:Insect Proteins; C031162:cecropin B protein, Insecta
keywords: Cecropin B; Citrus; Disease resistance; Genetic transformation; Huanglongbing; Phloem-specific promoter