Study on the biocontrol effect of Streptomyces sp. NEAU-KT41 and its cell-free culture filtrate against wheat root rot

Abstract

Wheat root rot, caused by Bipolaris sorokiniana, is a significant and extensive soilborne disease. Streptomyces sp. NEAU-KT41 was isolated from healthy wheat root soil and possessed strong antifungal activity against B. sorokiniana. Findings from the pot test indicated that strain NEAU-KT41 (108 CFU/mL) and its 10% cell-free culture filtrate had significant biocontrol efficiency against wheat root rot, with 66.67% and 64.4%, respectively, resulting in significant increases in biomass and chlorophyll content. For 108 CFU/mL spore suspension, the plant height increased by 167.52%; root length by 141.64%, fresh weight by 65%, chlorophyll a by 13.43%, and chlorophyll b by 51.02% under disease stress. For the 10% cell-free culture filtrate, the plant height increased by 21.93%, root length by 17.92%, dry weight by 29.35%, chlorophyll a by 17.92%, and chlorophyll b by 82.15% under disease stress. Moreover, strain NEAU-KT41 could produce proteases, amylases, lipases, and ACC deaminase, and had the ability to decompose organic phosphorus and fix nitrogen. The cell-free culture filtrate affected B. sorokiniana in several manners, including increasing the cell membrane permeability, diminishing the soluble protein content in the mycelia, impeding conidia germination and germ tube extension, and affecting B. sorokiniana invasion of plants. Briefly, Streptomyces sp. NEAU-KT41 is a prospective biocontrol agent that can be used to manage root rot in wheat and has potential applications.