石莼多糖通过抑制黑色素合成降低苹果炭疽叶枯菌分生孢子的侵染  

Ulvan Reducing Infection of Conidia of Glomerella Leaf Spot Pathogen through Inhibiting Melanin Synthesis

作　　者：李宏利 杨春颖 李婷婷 李平亮 李保华 练森 Li Hongli;Yang Chunying;Li Tingting;Li Pingliang;Li Baohua;Lian Sen(College of Plant Health and Medicine,Qingdao Agricultural University/Qingdao Engineering Research Center of Vegetable Pest Precise Control,Qingdao 266109,China)

机构地区：[1]青岛农业大学植物医学学院/青岛市果蔬病虫害精准防控工程研究中心,山东青岛266109

出　　处：《山东农业科学》2025年第3期152-157,共6页Shandong Agricultural Sciences

基　　金：国家重点研发计划项目(2023YFD1401404);国家苹果产业技术体系项目(CARS-27);山东省自然科学基金项目(ZR2020MC114)。

摘　　要：炭疽叶枯病是苹果生产上主要的早期落叶病,石莼多糖能提升苹果对炭疽叶枯病的抗性。本研究通过室内接种、孢子萌发和实时荧光定量PCR方法探究石莼多糖对炭疽叶枯菌侵染的抑制作用及机制。结果表明,石莼多糖处理后接种和先接种后石莼多糖处理的苹果叶片和果实的平均发病率分别为19.35%和18.50%,而对照和接种后24 h后再用石莼多糖处理的叶片和果实的平均发病率分别为36.50%和46.83%,病原菌侵入早期石莼多糖处理可降低炭疽叶枯病的发生率;石莼多糖促进分生孢子芽管持续伸长,不能形成黑化的附着胞,也不能形成有效的侵染钉;组织学观察表明石莼多糖处理后的附着胞在叶片上仅部分形成侵染钉,但没有进一步发育和刺破寄主表皮细胞;实时荧光定量PCR表明石莼多糖处理6、12、24 h时黑色素合成相关基因CfSCD相对表达量分别降至对照的18.2%、31.3%、47.6%。综上,石莼多糖通过促进炭疽叶枯菌分生孢子芽管生长,减少附着胞的形成,抑制黑色素合成,从而降低分生孢子对寄主的侵染。本研究结果为石莼多糖在炭疽叶枯病防治中的应用探明了方向,可为炭疽叶枯病的绿色防治提供技术途径。Apple Glomerella leaf spot is the main early defoliation disease in China at present.Ulvan is a polysaccharide from the cell wall of Ulva green algae,which has rich physiological activity to organisms and can improve the resistance of apple to Glomerella leaf spot.In this experiment,the mechanism of ulvan inhibiting the injection of Glomerella leaf spot was studied by indoor inoculation,spore germination and real-time quantitative PCR.The results showed that the average incidence rate of the leaves and fruits treated with ulvan before or after inoculation were 19.35%and 18.50%,respectively,while that of the control and treated with ulvan after 24 hours of inoculation were 36.50%and 46.83%,respectively.Treating with ulvan at early stage of pathogen invasion reduced the incidence of Glomerella leaf spot.Ulvan promoted the continuous elongation of conidial germinated tube,and could not form dark appressorium or effective infection pegs.Histological observation showed that the appressorium treated with ulvan only partially formed infection pegs on the leaves,but did not further develop and pierce the host epidermal cells.The real-time quantitative PCR showed that the relative expression level of the melanin synthesis-related gene CfSCD at 6,12 and 24 hours of ulvan treatment reduced by 18.2%,31.3%and 47.6%,respectively,compared with the control.In conclusion,ulvan reduced the infection of conidia through promoting the growth of conidial germinated tubes,reducing the formation of appressorium and inhibiting the melanin synthesis.These results of this study proved the application direction of ulvan on controlling Glomerella leaf spot,and also could provide a technical way for green prevention and control of Glomerella leaf spot.

关 键 词：石莼多糖 苹果炭疽叶枯病 分生孢子 侵染 附着胞 

分 类 号：S436.611.12[农业科学—农业昆虫与害虫防治]