Induction of Systemic Resistance Developed by Bioagents to Protect Papaya against Papaya Ring Spot Virus

Abstract

Papaya ring spot disease, caused by the Papaya ring spot virus (PRSV), is a major limiting factor in papaya cultivation in the Marathwada region of Maharashtra, it has potential to cause up to 100% yield loss. The present study aimed to investigate the effect of eleven bioagents viz., Trichoderma asperellum, Trichoderma harzianum, Verticillium lecanii, Bacillus subtilis, Pseudomonas fluorescens, PPMF, Streptomyces californicus, Metarhizium anisopliae, Beauveria bassiana, Biomix and an untreated control, in inducing resistance against PRSV under greenhouse conditions. The bioagents were applied using three different methods such as seed soaking in bioagents, pre-inoculation with bioagents and post-inoculation with bioagents. Among the bioagents tested, Bacillus subtilis and Pseudomonas fluorescens were most effective in inducing resistance to PRSV. Some of the positive effects of using bioagents were prolonged incubation period, reduced disease incidence, with milder reactions to Papaya ring spot virus compared to the untreated control. Additionally, while all bioagents contributed to enhanced plant height in papaya, Bacillus subtilis, Pseudomonas fluorescens and Streptomyces californicus were observed to be particularly effective.