Enhancing the pathogenicity of Arthrobotrys conoides and A. oligospora against Meloidogyne java']javanica J2 by transferring of protease (Ac1) gene and evaluation of antagonistic capability of transgenic isolates

Antagonistic fungi are well-known as viable alternatives to chemical control of root-knot nematodes. In this paper, serine protease Ac1 as an important pathogenicity factor was used to enhance the antagonistic activity of Arthrobotrys conoides and A. oligospora against Meloidogyne javanica J(2) (second stage juveniles). Ac1 gene was extracted from A. conoides and cloned in pCAMBIA1304 vector. The recombinant plasmid was then transferred to these fungi using two strains of Agrobacterium tumefaciens (LBA4404 and AGL1). Transgenic isolates were confirmed by PCR amplification of Hygromycin B resistance gene (hph) as selectable marker, protease assay using casein substrate and in vitro bioassay. Transferring of Ac1 gene by homologous recombination to A. conoides, increased protease activity. Our results showed that production of protease in both transgenic species was increased compared to wild type. Bioassay results indicated that pathogenicity rates of transformants, in both the number of traps formed and the number of trapped J(2), increased compared to the wild type. The results showed that inhibition of root-knot nematode, M. javanica, was markedly increased by transgenic isolates of Arthrobotrys spp. compared to the wild types.