Migration Of Pinewood Nematode Promotes The Colonization Of Esteya Vermicola In Pine Tree

Esteya vermicola is a potential biological agent of the pinewood nematode (PWN), Bursaphelenchus xylophilus, due to its high infectivity. However, knowledge of E. vermicola colonization in the host pine tree is less known. To reveal the distribution pattern of E. vermicola inside the pine tree and the interactions between fungus and PWN, biocontrol tests were conducted on 10 years old Pinus densiflora. A green fluorescence protein (GFP)-tagged E. vermicola was used to observe the fungal hyphae. Real-time TaqMan PCR quantification was applied to quantify the fungal hyphae in host tree. The results suggest that inoculation with the fungus significantly improved the survival rate of tested trees. Besides, the number of PWN extracted from fungal inoculated tested trees significantly decreased. Moreover, the fungal hyphae and lunate conidia grown in tested trees were observed with the GFP-tagged E. vermicola. The real-time quantification of E. vermicola illustrated the differential distribution of E. vermicola in wilted, wilting and healthy pine trees. Additionally, the promotion of fungal hyphal dispersion by B. xylophilus was found in the pine trees artificially infected with PWN. This study reveals the distribution of E. vermicola and PWN during biocontrol of pine wilt disease and provides direct evidence of the effectiveness of this fungus to control PWN. The migration of PWN infected by E. vermicola was supposed to improve the fungal extension in host pine tree.