Tapping Into the Cotton Fungal Phytobiome for Novel Nematode Biological Control Tools

Abstract

A number of fungi have been shown to have negative effects on plant-parasitic nematodes. Most of these fungi have been isolated from soil, plant roots, or nematodes themselves. Fungi associated with crops can provide a diverse pool of candidates to test for antagonistic effects against plant parasites and other stressors. We used a hierarchical two-tiered approach to evaluate the efficacy and repeatability of 55 strains of fungi originally isolated as foliar facultative endophytes from upland cotton (Gossypium hirsutum) along with one commercial isolate of Beauveria bassiana for in planta antagonistic effects on root-knot nematodes (Meloidogyne incognita). All fungi were inoculated to cotton using a seed treatment. The number of root galls was quantified 3 weeks after egg inoculation of cotton seedlings. The majority of the fungi tested reduced the number of root galls relative to those on untreated control plants. To assess repeatability, 22 strains that exhibited the strongest reductions in gall numbers were further tested in replicate follow-up assays. Ninety-five percent (21/22) of these retested strains significantly reduced galling in the follow-up assay. Strains that reduced galling the most belonged to the genera Alternaria, Chaetomium, Cladosporium, Diaporthe, Epicoccum, Gibellulopsis, and Purpureocillium. On the contrary, three strains in the genera Alternaria and Curvularia significantly increased gall numbers. Our results indicate that a large proportion of the fungal strains originally isolated from cotton as naturally occurring foliar facultative endophytes are capable of reducing root-knot nematode infection when applied back to the plant as a seed treatment. These findings help establish a rich pool of candidate fungi for further evaluation as novel biological control tools against root-knot nematodes in cotton and other plants.

Endophytic Fungal Community of Huperzia serrata: Diversity and Relevance to the Production of Huperzine A by the Plant Host

“…Eleven potential novel species belonged to the genera Amycolatopsis , Luteimicrobium , Glaciihabitans , Angustibacter , Massilia , Arthrobacter , Curtobacterium , Frondihabitns , Jatrophihabitans , Naumannella , and Tardiphaga , and one novel genus of the Dermacoccaceae family were dominant in H. serrate [ 70 ]. It is suggested that some fungal strains show antimicrobial activity against bacteria such as Bacillus cereus (Gram-positive) and E. coli (Gram-negative) and effectively decreased nematode infections in certain plant roots [ 71 , 72 ]. Endophytic fungi live in plants for a certain stage in their life cycle, but do not cause visible symptoms in plant tissues.…”

Illumina-based analysis yields new insights into the diversity and composition of endophytic fungi in cultivated Huperzia serrata

“…Some strains of Oidiodendron were reported to promote nitrogen uptake and plant growth [34], and exhibit metal tolerance [35]. Some strains of Cladosporium exhibited an antimicrobial activity against Bacillus cereus IIIM 25 (Gram positive) and Escherichia coli ATCC 25922 (Gram negative) [36], and effectively reduced the infection of nematodes in some plant roots [37]. The genera of Oidiodendron and Cladosporium might confer similar benefit upon the host H. serrata.…”

Fungal Endophytes and Their Role in Agricultural Plant Protection against Pests and Pathogens

“…Root-knot nematodes, represented by Meloidogyne species, are globally ubiquitous and impact over 2000 plant species including economically important crops such as tomato, cotton, cucumber, melon, soybean and rice [ 104 , 106 , 107 , 108 , 109 , 110 , 111 , 112 ]. Many fungal genera have been reported as having inhibitory effects on Meloidogyne species, including: Acremonium , Alternaria , Arthrobotrys , Chaetomium , Cladosporium , Clonostachys , Diaporthe , Drechslerella , Epichloë , Epiccocum , Fusarium , Gibellulopsis , Melanconium , Metacordyceps , Monacrosporium , Neotyphodium , Paecilomyces , Phialemonium , Phyllosticta , Piriformospora , Purpureocillium , Talaromyces and Trichoderma [ 106 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 ]. Species from one or more of these genera have also been reported as having similar antagonistic effects towards other species of nematodes [ 106 ].…”