title: The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton.
abstract: Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop.
authors.affiliation: Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Starr
authors.affiliation: Biology Department, Widener University, Chester, PA 19013, USA.
authors.forename: Janice L
authors.initials: JL
authors.lastname: Krumm
authors.affiliation: Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA gasword@tamu.edu.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Sword
mesh_terms: D000818:Animals; D002597:Chaetomium / Q000502:physiology*; D060026:Endophytes / Q000502:physiology*; D003368:Gossypium / Q000382:microbiology*; D060434:Herbivory; D007814:Larva; D018517:Plant Roots / Q000382:microbiology; D013559:Symbiosis
keywords: Chaetomium globosum; beet armyworm; cotton aphid; defensive mutualism; fungal endophyte; root-knot nematode