Protocol for Biocontrol of Soybean Cyst Nematode with Root Endophytic Fungi

Abstract

Plant-parasitic nematodes (PPNs) are major plant pests worldwide and cause severe economic and yield losses. The sedentary endoparasites, root-knot nematodes (RKNs, Meloidogyne spp.) and cyst nematodes (CNs, Globodera spp. and Heterodera spp.), are among the most economically damaging PPNs. Piriformospora indica, a plant growth-promoting fungus isolated from the Thar Deserts of western India, has been shown to protect a wide range of plants from various biotic and abiotic stresses. To evaluate the potential of P. indica to protect soybean (Glycine max) seedlings from damage by the soybean cyst nematode (SCN), we amended soil with two different concentrations of P. indica (2.5 % w/w, T1, and 5 % w/w, T2) and inoculated with second-stage juveniles (J2s) of SCN in each treatment. After 60 days, abundance of nematode eggs was measured by calculating SCN egg population densities. We found that egg density/100 cubic cm soil was significantly decreased by 29.7 % and 36.7 %, respectively, in the soil amended with T1 and T2 compared to a control. Amendment with P. indica also had a strong growth- and yield-promoting effect in Soybean. Although root biomass was significantly decreased by 27.9 % and 33.5 % in the two treatments compared to the control, shoot biomass (dry weight) increased by 30.8 % and 8.2 % in the T1 and T2 treatments compared to the control. Additionally, plant development was accelerated and a 75 % increase in flowering was observed between the T1 treatment and the control. We conclude that P. indica used as a soil amendment decreases abundance of the SCN in soil and has plant growth-promoting properties that may help counteract yield losses due to plant-parasitic nematodes.