高寒退化草地委陵菜根围丛枝菌根菌(AMF)分离鉴定及促生效应

Isolation, identification and growth promotion of arbuscular mycorrhizal fungi (AMF) from Potentilla chinensis in degraded alpine grassland in the Qilian Mountains

从祁连山高寒退化草地优势植被钝裂委陵菜根围分离丛枝菌根真菌(AMF),鉴定并研究其促生效果,为农业生产和生态修复提供服务。用湿筛倾析-蔗糖离心法提取土壤AMF孢子,按形态挑出大量相同孢子并用燕麦盆栽法扩繁;通过形态学和18S rRNA基因分析鉴定;并通过燕麦盆栽试验(CK:不接菌;处理A:接种根内根孢囊霉(AMF1);处理B:接种本研究分离菌株AMF2)探寻AMF对燕麦苗期的促生作用。结果表明,分离扩繁出一株含量最多的丛枝菌根真菌AMF2,经形态学鉴定发现AMF2孢子颜色为白色、奶白色、黄棕色;孢子椭球形、球状、近球形;孢子直径在90~120μm;18S基因测序获得有效序列长度为673 bp,并与NCBI blast比对发现AMF2与根内根孢囊霉相似度为100%,故结合两种鉴定方法鉴定为根内根孢囊霉,GenBank序列号MK311327。盆栽试验表明,处理A和B的AMF侵染率达到70%和61%,根活力较CK相比,分别提高了206%和123%;AMF2使燕麦苗期株高、茎粗、叶绿素b含量分别增加11%、21%和3%,AMF1对燕麦苗期地上部分促生作用较弱;两种根内球囊霉均能够增加燕麦根系总根长、根体积、根表面积,降低根平均直径,特别是对直径0~1.0 mm根的影响,其中AMF2对燕麦苗期生长的促生效果较好。综上,本研究筛选得到的AMF2为根内根孢囊霉,不仅丰富了我国AMF菌种库,还为高寒退化草地生态修复提供了有效途径。

An arbuscular mycorrhizal fungus(AMF)species was isolated from Potentilla chinensis growing in degraded alpine grassland in the Qilian Mountains,and the AMF growth promotion effect was then identified,with a view to potential future application to provide agricultural benefit.The AMF spores in soil were extracted by wet-screen decantation-sucrose centrifugation,and cultured by potting with oats.Morphological characteristics and 18 S rRNA gene analysis were used to identify the AMF.With respect to morphological traits,the spore color of the isolated AMF ranged from white,through milky white,to yellowish brown,while spore shape ranged from ellipsoidal,through nearly spherical,to spherical.Spore diameter was 90-120μm.The effective 18 S sequence length was 673 bp.Compared by NCBI blast,the isolated AMF was 100%similar to Rhizophagus intraradices,so both the morphological and mRNA evidence were consistent with identification of the isolated AMF as R.intraradices(GenBank serial number MK311327).A culture test on oat seedlings was conducted with treatments:CK(not inoculated);A(inoculated with R.intraradices from a laboratory reference sample,AMF1);and B(inoculated with the isolated AMF,AMF2).The pot experiment showed that AMF2 increased the plant height,stem diameter and chlorophyll b content of oat seedlings by 10.70%,21.43%and 2.60%,respectively.AMF1 had a weaker effect on the aboveground growth of oat seedlings.AMF2 also increased the total root length,root volume,and root surface area of the roots of the oats,and reduced the average diameter of the roots,especially the diameter roots less than 1.0 mm diameter.To summarise,AMF2,the isolated strain of R.intraradices demonstrated a strong growth promotion effect on oat seedlings.Thus AMF2 is a useful addition to the AMF strain library in China,and also shows potential for agricultural use in ecological restoration of degraded alpine grassland.