Mycorrhizal Fungi Resistance Mechanism To Poplar Canker Disease

In this research, Poplar pathogenic fungi were isolated and, identificed, Poparl inoculation with the bacteria (Dothiorella garigaria Sacc) isolated from poplar canker diseaseulcer and mycorrhizal fungi, to study the growth, PR proteins and reactive oxygen species (ROS) scavenging enzymes involved in resistance to poplar canker disease, resistance substances content to explore the mechanism of mycorrhizal fungi enhanced resistance of poplar to canker. The main results were as follows:1.35 isolates from different poplars in yangling country were collected and identified by morphological characteristics firstly,The rDNA-ITS genetic diversity and phylogeny study of pathogenic fungi on trees. Five genera and 6 species were identified from these 35 isolates.Ascomycotina has 3 genera, 4 species,the others is Deuteromycotina which has 2genra,2 species. The rDNA-ITS sequence analysis on a666 and a669b with the GenBank sequence, the fungi strains a666 and a669b were identified as Dothiorella garigaria Sacc.2. Arbuscular mycorrhizal fungi (Glomus mosseae, GM) and ectomycorrhizal fungi (Boletus luridus, BL) inoculation of poplar (Populus×euramerieana.cv."74/76"), the The inoculation showed arbuscula mycorrhizal fungi is the best, the fllowing is ectomycorrhizal fungi , the worst is the control. The content of arbuscular mycorrhizal fungi and ectomycorrhizal fungi on root activity,chlorophyll and total soluble protein of poplar are increased 80% and 57%, 47% and 51%, 32% and 49% compared with the control, when poplar infected by D. gregaria .Arbuscular mycorrhizal and ectomycorrhizal poplar's infective rate and disease index are decreased by 58.7%, 57.6% and 40%, 53.7%.3. Mycorrhizal fungi will help poplar increase the activity of related enzymes involved in resistance to poplar canker disease when attacked by D. gregaria,The inoculation of the two different mycorrhizal fungi significantly increased superoxide dismutase (SOD), phenylalanin ammo-nialyase (PAL) activity and praline content compared with control, the SOD,PAL and Praline activity increased 80%,43%, 75%,47%and 73%,54 %, respectively. Inoculated mycorrhizal fungi are significantly promoted the free praline (Pro) and decreased MDA cotents in the seedlings compared with the control .MDA's activity of arbuscular mycorrhizal and ectomycorrhizal on poplar wered reduction compared with the control of 63%, 27%. Arbuscular mycorrhizal fungi inoculation was better than inoculation of ectomycorrhizal fungi.4. The total protein content of different mycorrhizal poplar are significantly increased compared with the control, For the total protein content increased is associated with disease resistance of poplar, So poplar with canker disease are produced pathogen related (PR)proteins. After inoculated with AMF,Chitinases,β-1,3-glucanases and PR proteins of the seedlings were induced when attacked by D. gregaria, but the chitinases,β-1,3-glucanases and PR proteins of EMC seedlings were inhibited when attacked by D. gregaria.