攀枝花苏铁珊瑚根共生放线菌鉴定及共生体养分吸收  

Identification of symbiotic actinomycetes in the coralloid roots of Cycas panzhihuaensis and nutrient uptake by the symbiont

作　　者：魏玉倩 陈健鑫 郑艳玲[1,2] 王芳[1,2] 马焕成[1,2] 王国娟[1,2] 伍建榕[1,2] WEI Yuqian;CHEN Jianxing;ZHENG Yanling;WANG Fang;MA Huancheng;WANG Guojuan;WU Jianrong(Yunnan Provincial Key Laboratory of Forest Disaster Warning and Control,National Forestry and Grassland Administration,Southwest Forestry University,Kunming 650224,Yunnan,China;Key Laboratory of Biodiversity Conservation in Southwest China,National Forestry and Grassland Administration,Southwest Forestry University,Kunming 650224,Yunnan,China)

机构地区：[1]西南林业大学云南省高校森林灾害预警控制重点实验室,云南昆明650224 [2]西南林业大学国家林业和草原局西南地区生物多样性保育重点实验室,云南昆明650224

出　　处：《中南林业科技大学学报》2022年第11期44-52,共9页Journal of Central South University of Forestry & Technology

基　　金：国家自然科学基金项目(31860208,31360198,31560207);西南林业大学木棉纤维人工林产业化培育省级创新团队项目(2018HC014);云南省教育厅科学研究基金项目(2021Y274)。

摘　　要：【目的】攀枝花苏铁是生长在干热河谷地区植被稀少土壤贫瘠的石质山地的一类古老植物。攀枝花苏铁的侧根特化为发达的珊瑚状根,提高了攀枝花苏铁根系对养分的利用,本研究旨在探明珊瑚状根内共生放线菌的种类及其对养分吸收的影响。【方法】采用稀释涂布法对原生地攀枝花苏铁珊瑚状根内放线菌进行分离培养,通过16S rRNA基因进行分子鉴定;将内生放线菌接种到无菌砂培苏铁苗根系,经18 m共生培养后,通过石蜡切片观察珊瑚状根内放线菌的定殖位置,并利用全自动间断化学分析仪及同位素示踪法探究氮素的吸收形式。【结果】珊瑚状根共生放线菌TB-6、TB-7和TB-10分别为Streptacidiphulus griseoplanus、Streptomyces spororaveu和S. xanthophaeus;共生培养后的无菌苏铁苗均能够形成珊瑚状根,石蜡切片显示放线菌定殖于根的外皮层和内皮层细胞中,证明它们与攀枝花苏铁形成共生体,没有共生的无珊瑚根形成;共生后的无菌苏铁苗根系全氮全磷全钾含量增加,氮素的积累量增加最为显著,同位素示踪结果显示,接种放线菌后形成珊瑚状根的苏铁苗吸收硝态氮和铵态氮的比例从1:1.3增加至1:2.03,表明接种放线菌能增加对铵态氮的吸收。【结论】原生地攀枝花苏铁能与放线菌形成珊瑚状根共生体,选择性吸收土壤中易被植物吸收利用的铵态氮,共生体通过提高苏铁根系对养分的吸收与利用,使得攀枝花苏铁能在干热河谷长期稳定地生存,本研究为攀枝花苏铁的保护繁育提供了理论支持。【Objective】Cycas panzhihuaensis is an ancient plant growing in rocky mountains with sparse vegetation and poor soil in the dry and hot river valley.The lateral roots of C.panzhihuaensis are specialized into developed coralloid roots,which improve the utilization and absorption of nutrients.This work aimed to clarify the species of symbiotic actinomycetes and their effects on nutrient absorption in coralloid roots.【Method】The endophytic actinomycetes were isolated and cultured by the dilution coating method,and molecular identification was carried out by the 16S rRNA gene.The endophytic actinomycetes were inoculated into the root system of sterile sand cultured Cycas seedlings.After 18 months of symbiotic culture,the colonization position of actinomycetes in the coral roots was observed by paraffin section,and the absorption of nutrients was studied by the automatic discontinuous chemical analyzer and isotope tracer method.【Result】The symbiotic actinomycetes of TB-6,Tb-7 and Tb-10 in the coralloid roots were identified as Streptomyces griseoplanus,S.spororaveu and S.xanthophaeus,respectively.The aseptic Cycas seedlings can form coralloid roots after symbiotic culture.Paraffin sections showed that actinomycetes were colonized in the outer and endothelial cells of roots.It was proved that they formed symbionts with Cycas panzhihuaensis,and no symbiotic coralline roots were formed.The content of total nitrogen,total phosphorus and total potassium in the root system of sterile Cycas seedlings increased after symbiosis.The increase in nitrogen accumulation was the most significant.Isotope tracing results showed that the ratio of nitrate nitrogen and ammonium nitrogen absorbed increased from 1:1.3 to 1:2.03 in the coralloid roots of Cycas after inoculation with actinomycetes,indicating that actinomycetes could increase the absorption of ammonium nitrogen by plants.【Conclusion】Actinomycetes can form coral root symbionts with native Cycas panzhihuaensis,and selectively absorb ammonium nitrogen which is eas

关 键 词：攀枝花苏铁 珊瑚状共生体 放线菌 氮素吸收 同位素标记 

分 类 号：S791.11[农业科学—林木遗传育种]