中国农业科学 ›› 2020, Vol. 53 ›› Issue (8): 1556-1571.doi: 10.3864/j.issn.0578-1752.2020.08.006

• 植物保护 • 上一篇    下一篇

转录因子CsWRKY61对柑橘溃疡病抗性的影响

龙琴,杜美霞,龙俊宏,何永睿,邹修平(),陈善春()   

  1. 西南大学/中国农业科学院柑桔研究所国家柑桔品种改良中心,重庆 400712
  • 收稿日期:2019-09-26 接受日期:2019-11-13 出版日期:2020-04-16 发布日期:2020-04-29
  • 通讯作者: 邹修平,陈善春
  • 作者简介:龙琴,E-mail: longlong860923@126.com。
  • 基金资助:
    国家重点研发计划(2018YFD1000300);重庆市自然科学基金-博士后基金(cstc2019jcyj-bshX0024);中央高校基本科研业务费(XDJK2019C027);国家现代农业产业技术体系建设专项资金(CARS-26)

Effect of Transcription Factor CsWRKY61 on Citrus Bacterial Canker Resistance

LONG Qin,DU MeiXia,LONG JunHong,HE YongRui,ZOU XiuPing(),CHEN ShanChun()   

  1. National Center for Citrus Variety Improvement, Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing 400712
  • Received:2019-09-26 Accepted:2019-11-13 Online:2020-04-16 Published:2020-04-29
  • Contact: XiuPing ZOU,ShanChun CHEN

摘要:

【背景】柑橘溃疡病(citrus bacterial canker,CBC)是世界柑橘产业上危害最严重的病害之一,由柑橘黄单胞杆菌柑橘亚种(Xanthomonas citri subsp. citri,Xcc)引起,在国内外被列为检疫对象。由于柑橘分子病理研究相对滞后,导致可供利用的抗性基因资源相对匮乏。WRKY转录因子参与植物抵御生物和非生物胁迫反应,前期研究发现柑橘WRKY转录因子可能在调控寄主抗病反应中起着重要作用。【目的】通过对超量表达CsWRKY50CsWRKY61CsWRKY72转基因晚锦橙(Citrus sinensis)的溃疡病抗性进行评价,明确这些基因在柑橘响应溃疡病菌侵染中的生物学功能和抗病育种价值。进一步利用RNA-Seq解析CsWRKY61调控的信号通路。【方法】利用农杆菌介导法进行柑橘遗传转化,获得超量表达CsWRKY50CsWRKY61CsWRKY72的晚锦橙;利用实时荧光定量PCR(qRT-PCR)分析转基因植株中目的基因的表达水平以及拷贝数;以非转基因植株为对照,采用离体针刺接种评价转基因植株对溃疡病的抗性;通过比较超量表达CsWRKY61和野生型植株的转录组测序结果,探究CsWRKY61提高柑橘溃疡病抗性的内在机制。【结果】分别构建了CAMV 35S启动子控制CsWRKY50CsWRKY61CsWRKY72表达的植物表达载体,通过GUS组织化学染色和PCR鉴定分别获得了6、8和6株转基因晚锦橙。转基因植株中目的基因的表达量有不同程度的提高,大部分转基因植株中外源基因的拷贝数为1,只有超量表达CsWRKY61的转基因植株溃疡病抗性显著增强,其病斑面积明显小于野生型植株,而超量表达CsWRKY50CsWRKY72的转基因植株抗病性与野生型相比无明显差异。转录组分析结果显示,超量表达CsWRKY61的转基因植株中生物胁迫相关途径(包括病原入侵的感知、活性氧爆发、转录因子、防御基因、激素、细胞壁和次生代谢等)和信号转导相关途径(主要是激酶受体)均被显著激活。【结论】超量表达CsWRKY61能够激活与生物胁迫和信号转导相关的途径,增强柑橘对溃疡病的抗性;CsWRKY61在柑橘抗病育种中存在潜在的应用价值。

关键词: 柑橘黄单胞杆菌柑橘亚种, 柑橘溃疡病, CsWRKY61, 超量表达, 抗病性, 转录组测序

Abstract:

【Background】Citrus bacterial canker (CBC) caused by Xanthomonas citri subsp. citri (Xcc) is one of the most serious citrus diseases in the world, which is a quarantine disease. Due to the relatively backward research of citrus molecular pathology, the available resistance gene resources are relatively scarce. WRKY transcription factor is involved in plant responses to biotic and abiotic stress. The previous study has found that citrus WRKY transcription factor may play an important role in regulating host disease resistance response.【Objective】The objective of this study is to evaluate the canker resistance of transgenic citrus (Citrus sinensis) with over-expression of CsWRKY50, CsWRKY61 and CsWRKY72, clarify the biological function and disease resistance breeding value of these genes in citrus in response to Xcc. RNA-seq was further used to analyze the signaling pathway regulated by CsWRKY61.【Method】Agrobacterium-mediated method was used to obtain transgenic citrus plants with over-expression of CsWRKY50, CsWRKY61 and CsWRKY72. Real-time quantitative PCR (qRT-PCR) was used to analyze the expression level and copy number of the target genes. In vitro pinprick inoculation was used to evaluate the resistance of transgenic plants to canker disease. The molecular mechanism of CsWRKY61 improving citrus bacterial canker resistance was investigated by transcriptome sequencing analysis of over-expression CsWRKY61 and wild-type (WT) plants.【Result】The plant expression vectors of CAMV 35S promoter controlling the expression of CsWRKY50, CsWRKY61 and CsWRKY72 were constructed, and 6, 8 and 6 transgenic lines were obtained by GUS staining and PCR identification, respectively. The expression of the target gene in transgenic plants increased in different degrees. The copy number of exogenous genes in most transgenic plants was 1. Only the transgenic plants with over-expression of CsWRKY61 had significantly enhanced canker disease resistance, and the lesion area was significantly smaller than that of WT plants, while over-expression of CsWRKY50 and CsWRKY72 transgenic plants had no significant difference in disease resistance compared with WT. Transcriptomics analysis showed that biotic stress related pathways (including pathogen recognition, respiratory burst, transcription factors, defense genes, hormones, cell wall and secondary metabolism, etc.) and signal transduction-related pathways (mainly kinase receptors) were significantly activated in over-expression of CsWRKY61 transgenic plants. 【Conclusion】Over-expression of CsWRKY61 can activate pathways related to biotic stress and signal transduction, enhance citrus bacterial canker resistance. It is suggested that CsWRKY61 has potential application value in citrus disease resistance breeding.

Key words: Xanthomonas citri subsp. citri (Xcc), citrus bacterial canker, CsWRKY61, over-expression, disease resistance, transcriptome sequencing