桉树根系共生真菌的分离与鉴定

Isolation and Identification of Symbiotic Fungi in Eucalyptus Roots

南方土壤缺磷现象较为严重,菌根真菌等共生真菌对植物吸收磷等养分具有重要的促进作用。该研究采集尾叶桉(Eucalyptus urophylla)、窿缘桉(Eucalyptus exserta)和尾巨桉(E.urophylla×E.grandis)3种华南地区主要造林树种根系,采用组织分离法进行真菌分离,通过形态特征和核糖体18SrDNA基因ITS序列分析进行鉴定,经柯赫氏法则(Kochs Rule)确定桉树根系共生真菌,为桉树共生真菌理论研究和资源利用提供依据。结果表明:(1)3种桉树根系中,窿缘桉具有外生菌根(ectomycorrhizas,ECM)和丛枝菌根(arbuscular mycorrhizas,AM)结构,尾叶桉和尾巨桉同时具有AM结构、ECM结构和深色有隔内生真菌(dark septate endophytes fungi,DSE)结构。(2)3种桉树根系中分离鉴定出6种真菌:三色小皮伞菌(Marasmius tricolor)、黑柄裸脚伞(Gymnopus melanopus)、茎点霉属(Phomasp.)、镰刀霉属(Fusariumsp.)、二型伞霉(Umbelopsis dimorpha)和芒弗里亚拟盘多毛孢(Pestalotiopsis mangifolia)。(3)6种真菌回接巨桉(Eucalyptus grandis)组培苗,三色小皮伞菌和黑柄裸脚伞形成ECM结构,为ECM真菌;茎点霉属、镰刀霉属、二型伞霉和芒弗里亚拟盘多毛孢形成DSE典型的深色有隔菌丝和微菌核结构,推测为DSE;其中2种ECM真菌为桉树中首次报道。

Phosphorus deficiency is severe in soil in south China.Symbiotic fungi plays an important role in plants uptaking phosphorus and other nutrients,such as mycorrhizal fungi.In this study,we sampled the roots of three main tree species in south China,Eucalyptus urophylla,Eucalyptus exserta,and E.urophylla×E.grandis.Root tissue separation was used to isolate and purify the fungi,which identified by morphological characteristics and ITS sequence analysis of 18S rDNA gene,and symbiotic fungi of Eucalyptus roots were validated by Koch s Rule.This study provides scientific evidence for theory research on symbiotic fungi in Eucalyptus roots and its resource utilization.The results showed that:(1)the collected roots of E.exserta displayed both ectomycorrhizas(ECM)and arbuscular mycorrhizas(AM)structures.Interestingly,both E.urophylla and E.urophylla×E.grandis possessed the structures of AM,ECM and dark septate endophytes(DSE).(2)Six fungi were isolated and identified from the roots of three species of Eucalyptus:Marasmius tricolor,Gymnopus melanopus,Phoma sp.,Fusarium sp.,Umbelopsis dimorpha,and Pestalotiopsis mangifolia,respectively.(3)Six fungi were inoculated back to roots of E.grandis tissue culture seedlings,M.tricolor and G.melanopus are able to form ECM structure in host roots as ECM fungi,whereas other four species of fungi(Phoma sp.,Fusarium sp.,U.dimorpha,and P.mangifolia)formed the dark color mycelium and microsclerotia in roots,the typical DSE structure,which were speculated to be DSE.The two ECM fungi were firstly reported in Eucalyptus roots.