A study on tomato brown rugose fruit virus longevity in soil and virion susceptibility to various pH treatments contributes to optimization of a soil disinfection protocol

Abstract

Background and aims: Tobamoviruses are highly stable soil-borne pathogens posing a challenge to a monoculture practice. Biochemical and physical properties of tobamovirus virions were studied by analyses of tobacco mosaic virus (TMV). Little is known about tomato brown rugose fruit tobamovirus (ToBRFV) regarding longevity in soil and virion stability. Our aims were to determine ToBRFV longevity in naturally-contaminated soil and study virion stability in a range of acidic and alkaline conditions to promote new strategies for soil remediation. Methods: ToBRFV longevity in naturally-contaminated soil was tested by collecting an earth pile after a growth-cycle of ToBRFV-infected tomato plants. The soil was sampled at different time points and root-truncated tomato seedlings were planted. Virion stability at a range of pH values was determined by testing virus infectivity on Nicotiana glutinosa; by amplifying large genome segments using RT-PCR; and by transmission electron microscopy (TEM) visualization. Results: ToBRFV-infectivity in naturally-contaminated soil was profoundly reduced by day 184 of pile-age and was abolished between 205-385 days of pile-age. Virion stability and genome integrity were preserved over the pH range of 2-10. At pH 1, ToBRFV-infectivity and efficiency of large genome segment amplifications were reduced. At pH values above 10, modified particle morphologies were visualized by TEM, and virus infectivity was abolished. Treatment of ToBRFV-contaminated soil with an alkaline chlorinated-trisodium phosphate solution profoundly reduced soil-mediated virus infection of root-truncated tomato seedlings. Conclusions: pH values above 10, compromised ToBRFV particle morphology genome integrity and virus infectivity. Alkaline disinfectant enhanced soil remediation following natural ToBRFV contamination.