World Journal of Microbiology & Biotechnology 2015-04-01

Transformation of the endophytic fungus Acremonium implicatum with GFP and evaluation of its biocontrol effect against Meloidogyne incognita.

Yu-Rong Yao, Xue-Liang Tian, Bao-Ming Shen, Zhen-Chuan Mao, Guo-Hua Chen, Bing-Yan Xie

Index: World J. Microbiol. Biotechnol. 31(4) , 549-56, (2015)

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Abstract

Acremonium implicatum is an endophytic fungus with biocontrol potential against Meloidogyne incognita based on its opportunistic egg-parasitic, hatching inhibition, and toxic properties. To understand its mode of plant endophytism and opportunistic egg parasitism, GFP-tagged A. implicatum was constructed by PEG-mediated protoplast transformation. By laser scanning confocal microscopy (LSCM), we evaluated the endophytism and opportunistic egg parasitism of a stable gfp transformant (Acr-1). Acr-1 could colonize epidermal tissue, cortical tissue, and xylem of roots and form a mutualistic symbiosis with tomato host plants. LSCM of Acr-1 infecting M. incognita eggs revealed that hyphae penetrated the shell and grew inside eggs to form trophic hyphae. A large number of hyphae enveloped parasitized eggs. In addition, the egg shell integrity was destroyed by fungal penetration. The percentage of egg parasitism was 33.8 %. There were no marked differences between the wild type and mutant in nematode second-stage juvenile mortality and egg hatching and in fungal control efficiency in a pot experiment. In conclusion, gfp-transformation did not change the nematicidal activity of A. implicatum and is a tool to examine the mode of plant endophytism and opportunistic egg parasitism of A. implicatum.