Diversity of Nematode Microbial Antagonists from Algeria Shows Occurrence of Nematotoxic <i>Trichoderma</i> spp.

• Main Authors: Nawal Benttoumi, Mariantonietta Colagiero, Samira Sellami, Houda Boureghda, Abdelaziz Keddad, Aurelio Ciancio
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Plants
• Subjects: biocontrol; Globodera rostochiensis; Meloidogyne; Trichoderma; Fusarium; TRI gene
• Online Access: https://www.mdpi.com/2223-7747/9/8/941

Fungi and bacteria associated to phytoparasitic nematodes <i>Globodera rostochiensis</i> and <i>Meloidogyne</i> spp. in Algeria were identified and characterized. <i>Trichoderma</i> spp. showed the highest prevalence in the cysts of <i>G. rostochiensis</i>.<i> </i>A number of isolates were identified through PCR amplification and the sequencing of the internal transcribed spacer (ITS)1-2 and <i>Rpb2</i> gene regions. The most represented species were <i>T. harzianum </i>and <i>T. afroharzianum</i>. The latter and <i>T. hirsutum</i> were reported for the first time in Algeria. <i>Fusarium</i> spp., including <i>F. oxysporum</i> and <i>F. solani</i>, comprised a second group of fungi found in cysts. Taxa associated to females of <i>Meloidogyne</i> spp. included <i>T. harzianum</i>,<i> Fusarium</i> spp. and other hyphomycetes. To assess the efficacy of <i>Trichoderma</i> spp., two assays were carried out in vitro with the culture filtrates of two <i>T. afro</i><i>harzianum</i> and <i>T</i>. <i>harzianum</i> isolates, to check their toxicity versus the second stage juveniles of <i>M. incognita</i>. After 24–48 hrs exposure, a mortality significantly higher than the control was observed for both filtrates at 1% dilutions. The <i>TRI</i> genes involved in the production of trichothecenes were also amplified with the PCR from some <i>Trichoderma</i> spp. isolates and sequenced, supporting a putative role in nematode toxicity. Bacteria isolated from the cysts of <i>G. rostochiensis</i> included Brucella, Rhizobium, Stenotrophomonas and Bacillus<i> </i>spp., identified through 16S rRNA gene sequencing. The potential of the microbial isolates identified and their mechanisms of action are discussed, as part of a sustainable nematode management strategy.