| Summary: | The endoparasitic fungus <i>Hirsutella rhossiliensis</i> is an important biocontrol agent of cyst nematodes in nature. To determine the potential parasitism of the fungus on a non-natural host, the pinewood nematode (<i>Bursaphelenchus xylophilus</i>) living in pine trees and the endophytic ability of the fungus on plants, in this paper, we first constructed and utilized a green fluorescent protein (GFP)-tagged <i>H. rhossiliensis</i> HR02 transformant to observe the fungal infection process on <i>B</i>. <i>xylophilus</i> and its colonization on <i>Arabidopsis</i> roots. Then, we compared the fungal parasitism on three species of nematodes with different lifestyles, and we found that the fungal parasitism is correlated with nematode species and stages. The parasitic effect of <i>H. rhossiliensis</i> on adults of <i>B. xylophilus</i> is similar to that on second-stage juveniles (J2) of the root-knot nematode <i>Meloidogyne incognita</i> after 24 h of inoculation, although the virulence of the fungus to second-stage juveniles of <i>M. incognita</i> is stronger than that to those of <i>B. xylophilus</i> and <i>Caenorhabditis elegans</i>. Moreover, the endophytism of <i>H. rhossiliensis</i> was confirmed. By applying an appropriate concentration of <i>H. rhossiliensis</i> conidial suspension (5 × 10<sup>6</sup> spores/mL) in rhizosphere soil, it was found that the endophytic fungus can promote <i>A. thaliana</i> growth and reproduction, as well as improve host resistance against <i>M. incognita.</i> Our results provide a deeper understanding of the fungus <i>H. rhossiliensis</i> as a promising biocontrol agent against plant-parasitic nematodes.
|
|---|