AUTHOR=Shukla Vaishali , Kumar Sunil , Tripathi Yashoda Nandan , Upadhyay Ram S. 

TITLE=Bacillus subtilis- and Pseudomonas fluorescens-Mediated Systemic Resistance in Tomato Against Sclerotium rolfsii and Study of Physio-Chemical Alterations

JOURNAL=Frontiers in Fungal Biology

VOLUME=Volume 3 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/fungal-biology/articles/10.3389/ffunb.2022.851002

DOI=10.3389/ffunb.2022.851002

ISSN=2673-6128

ABSTRACT=The present study is a comparative study between ROS signaling and antioxidative enzymatic signaling and deals with induced systemic resistance (ISR) in enhancing the disease resistance in typical tomato plant (Solanum lycopersicum L.) infected by collar rot fungus Sclerotium rolfsii (Teleomorph: Athelia rolfsii) by priming with Bacillus subtilis, Pseudomonas fluorescence and their microbial consortia. The novelty of the current experiment is developing microbial consortium with gram positive (B1) and gram negative (P1) bacteria in monitoring severity of collar rot fungus. Leaf samples were collected after different durations of pathogen inoculation, i.e., 1, 2, 3 and 4 days, and the systemic level of oxidative stress parameters such as hydrogen peroxide, photosynthetic apparatus, superoxide radicals and enzymatic antioxidants were studied. Plant mortality under various treatments in two different seasons was calculated. The highest H2O2 was scavenged by the microbial consortium- treated plants (B1P1) and the lowest in pathogen- challenged plants (PC) compared to untreated control. Cellular damage and reduction in chlorophyll pigments were highest at 48 h, and the photosynthetic efficiency (Fv/Fm) was evaluated from 24-96 h; the lowest values were observed for pathogen- challenged plants and the highest for B1P1. Enzymatic antioxidants showed the maximum value for B1P1 and the minimum for PC compare to unchallenged control. Furthermore, an analysis of variance and principal component analysis were conducted to examine the effect of the evaluation time (ET) and inoculation conditions (IC) alone and in combination (ET×IC) on physiological and biochemical parameters; accordingly, the score and loading plots were constructed. Tomato root sections inoculated with different treatments were observed through scanning electron microscopy (SEM) to validate potentiality of primed biocontrol agents in controlling invasion of pathogen.