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园艺学报 ›› 2020, Vol. 47 ›› Issue (6): 1047-1058.doi: 10.16420/j.issn.0513-353x.2019-0764

• 研究论文 • 上一篇    下一篇

溃疡病菌侵染早期柑橘细胞程序性死亡的响应特征及机制

龙 琴,谢 宇,许兰珍,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,国家柑桔工程技术研究中心,重庆 400712
  • 出版日期:2020-06-25 发布日期:2020-06-25
  • 基金资助:
    国家重点研发计划项目(2018YFD1000300);重庆市自然科学基金—博士后基金项目(cstc2019jcyj-bshX0024);中央高校基本科研业务费项目(XDJK2019C027);国家现代农业产业技术体系建设专项资金项目(CARS-26)

Characteristics and Mechanism of Programmed Cell Death in Response to Citrus Canker Pathogen in the Early Stage of Infection

LONG Qin,XIE Yu,XU Lanzhen,HE Yongrui,ZOU Xiuping*,and CHEN Shanchun*   

  1. National Citrus Engineering Research Center,Citrus Research Institute,Southwest University/Chinese Academy of Agricultural Sciences,Chongqing 400712,China
  • Online:2020-06-25 Published:2020-06-25

摘要: 为进一步研究柑橘溃疡病抗性与细胞程序性死亡的关系, 以高感品种晚锦橙(甜橙类,Citrus sinensis Osbeck)和高抗品种金弹(金柑类,Fortunella crassifolia Swingle)为试材,从抗性特征、发病早期的相关信号变化、抗氧化酶活性和基因表达变化等方面探讨柑橘细胞程序性死亡响应溃疡病菌(Xanthomonas citri subsp. citri)侵染的特征及机制。接种溃疡病菌后,晚锦橙叶片出现明显的海绵状凸起,为典型的溃疡病症状;而金弹则出现超敏化反应细胞坏死症状。接种前,过氧化氢(H2O2)在金弹中的基础水平较晚锦橙高;接种后,两品种的H2O2含量均上升,但金弹上升幅度高于晚锦橙。随着H2O2水平升高,代表膜脂过氧化程度的丙二醛(MDA)含量在两个品种中均增加,但金弹中增加幅度更大。抗氧化酶系统中的超氧化物歧化酶(SOD)活性在晚锦橙和金弹叶片中均呈下降趋势;过氧化氢酶(CAT)活性在两个品种中均提高且差异不大;过氧化物酶(POD)活性在两个品种中均提高,但晚锦橙的上升更快,且提高程度低于对照。参与细胞程序性死亡正调控的基因CsCEP1-1、CsCEP1-2和CsMCA1在两个品种中均受溃疡病菌诱导上调表达,但金弹中的表达水平显著高于晚锦橙;参与细胞程序性死亡负调控的CsDAD1-1、CsDAD1-2、CsMLO2和CsMLO3的转录水平在晚锦橙中变化不大,而金弹中随着接种时间的延长逐渐降低。结果表明,溃疡病菌胁迫下晚锦橙和金弹在发病早期均启动了超敏化反应,但在金弹中更为强烈,有助于诱导发生细胞程序性死亡,而限制病原菌的生长,这可能是金弹抗病性强的内在原因之一。

关键词: 柑橘, 溃疡病, 细胞程序性死亡, 活性氧, 丙二醛, 抗氧化酶, 基因表达

Abstract: To further investigate the relationship between citrus canker disease resistance and programmed cell death(PCD),the dynamics of PCD related signals,antioxidant enzyme activities and gene expression upon Xanthomonas citri subsp. citri(Xcc)infection were studied in susceptible variety Wanjincheng orange(Citrus sinensis Osbeck)and resistant variety Jindan(Fortunella crassifolia Swingle). Typical canker symptoms of pustule were observed in Wanjincheng orange,while hypersensitive necrosis(blown region)occurred in Jindan after inoculation with Xcc. The base level of hydrogen peroxide(H2O2)in Jindan was higher than that of in Wanjincheng orange before inoculation. After inoculation,the content of H2O2 increased in the two varieties,but the content in Jindan was always higher than that in Wanjincheng orange. Following the increase of H2O2 level,the content of malondialdehyde(MDA),which indicates the degree of membrane lipid peroxidation also increased in two varieties,but much higher in Jindan. The activity of superoxide dismutase(SOD),which is involved in scavenging reactive oxygen species decreased in the leaves of two varieties. The activity of catalase(CAT)increased in the two varieties,but no significant difference between them. Moreover,the activity of peroxidase(POD)increased in both varieties,but more rapidly in Wanjincheng orange,and the increase was lower than that of the water treatment control. The expression of CsCEP1-1,CsCEP1-2 and CsMCA1 which positively regulate the PCD were up-regulated by Xcc in two varieties,while much higher in Jindan. The transcription levels of CsDAD1-1,CsDAD1-2,CsMLO2 and CsMLO3,which negatively regulate the PCD did not significantly change in Wanjincheng orange,but gradually decreased in Jindan. The results showed that both susceptible and resistant varieties initiated the hypersensitive reaction in response to the Xcc infection. However,the reaction was more drastic in the resistant variety,which may lead to the induction of PCD and resulted to the resistance of Jindan to Xcc.

Key words: citrus, canker disease, programmed cell death, reactive oxygen species, malondialdehyde, antioxidant enzyme, gene expression

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