Trichovariability in rhizosphere soil samples and their biocontrol potential against downy mildew pathogen in pearl millet

Abstract

The present work is aimed to examine the genetic variability and the distribution pattern of beneficial Trichoderma spp. isolated from rhizosphere samples and their mode of action in improving the plant health. A total of 131 suspected fungi were isolated from the rhizospheric soil and 91 isolates were confirmed as Trichoderma spp. T. asperellum and T. harzianum were found high in the frequency of occurrence. Genetic diversity analysis using RAPD and ISSR revealed the diverse distribution pattern of Trichoderma spp. indicating their capability to adapt to broad agroclimatic conditions. Analysis of genetic diversity using molecular markers revealed intra-species diversity of isolated Trichoderma spp. The frequency of pearl millet (PM) root colonization by Trichoderma spp. was found to be 100%. However, they showed varied results for indole acetic acid, siderophore, phosphate solubilization, β-1,3-glucanase, chitinase, cellulase, lipase, and protease activity. Downy mildew disease protection studies revealed a strong involvement of Trichoderma spp. in direct suppression of the pathogen (mean 37.41) in the rhizosphere followed by inducing systemic resistance. Our findings highlights the probable distribution and diversity profile of Trichoderma spp. as well as narrate the possible utilization of Trichoderma spp. as microbial fungicides in PM cultivation across different agroclimatic zones of India.