Development of formulations based onStreptomyces rocheistrain PTL2 spores for biocontrol ofRhizoctonia solanidamping-off of tomato seedlings

Abstract

Rhizoctonia solani is one of the most problematic soil-borne pathogenic fungi for several crop cultures worldwide. This study highlights the effectiveness of high-antagonistic Streptomyces rochei strain PTL2, isolated from root tissues of Panicum turgidum, in controlling the R. solani damping-off and growth promotion of tomato (cv. Marmande) seedlings. The isolate PTL2 was characterised for in vitro biocontrol and plant growth-promoting traits. It exhibited remarkable positive results in all trials, including production of hydrogen cyanide, siderophores, 1aminocyclopropane-1-carboxylate deaminase and phytohormones, chitinolytic activity and inorganic phosphate solubilisation. PTL2 spores were formulated as wettable talcum powder, sodium alginate pellets and sodium alginate-clay pellets. Their abilities in the biocontrol of R. solani and plant growth promotion were investigated in autoclaved and non-autoclaved soils. Talcum powder and sodium alginate pellets significantly reduced the damping-off severity index compared to a positive control. The talcum powder exhibited the highest protective activity, reducing the disease incidence from 89.3% to 14.1%, whereas chemical seed treatment with Thiram ® provided a disease incidence of 16.7%. Furthermore, the talc-based powder formulation resulted in greatest increases in the root length, shoot length and dry weight of seedlings. The interesting biocontrol potential and growth enhancement of tomato seedlings open up promising perspectives for the possible application of talcum powder formulation based on PTL2 spores in crop improvement.

Biocontrol and plant-growth-promoting capacities of actinobacterial strains from the Algerian Sahara and characterisation ofStreptosporangium becharenseSG1 as a promising biocontrol agent

“…Several studies have already reported that antagonist Streptomyces species can be considered as active against numerous phytopathogenic fungi, such as F. oxysporum f. sp. radicis-lycopersici, F. culmorum and R. solani (Yekkour et al, 2012;Zamoum et al, 2017), and have suggested their use as biocontrol agents, or their involvement in the in vivo biocontrol of wheat root rot caused by F. culmorum (Toumatia et al, 2015). The study by El-Tarabily, Hardy GES, Sivasithamparam, Hussein, and Kurtboöke (1997) was the first to provide evidence of the utility of Streptosporangium albidum in the biocontrol of Pythium coloratum.…”

“…Cultures were incubated at 30°C for 5 days. Chitinolytic activity was estimated by measuring the diameter of the hydrolytic halo surrounding the actinobacterial colonies (Zamoum, Goudjal, Sabaou, Mathieu, & Zitouni, 2017).…”

Desert Microbes for Boosting Sustainable Agriculture in Extreme Environments

“…A potential biocontrol Streptomyces strain was isolated from the roots of the Saharan native plant P. turgidum (Zamoum et al, 2017), this Streptomyces strain was identified as S. rochei strain PTL2 and showed a number of PGP traits including the production of hydrogen cyanide (HCN), siderophores, ACC deaminase, and phosphate solubilization. Furthermore, this PLT2 strain showed strong antagonistic activity against the soil-borne pathogenic fungus Rhizoctonia solani, revealing the potential use of this desert PGPR as a biocontrol agent, which could help various crop plants against plant pathogens (Zamoum et al, 2017). In addition, Nocardiopsis dassonvillei MB22 with a strong biocontrol activity was isolated from the Saharan soils and showed several PGP traits including the production of IAA, HCN, and phosphate solubilization (Allali et al, 2019).…”

Screening of Tomato Seed Bacterial Endophytes for Antifungal Activity Reveals Lipopeptide Producing Bacillus siamensis Strain NKIT9 as a Potential Bio-Control Agent

“…because of their diverse host spectra and soil-borne existence, fungal phytopathogens are difficult to control ( Lamichhane et al, 2017 ). R. solani is one of the most important and widespread soil-borne phytopathogenic fungi causing yield losses in more than 200 crops around the world ( Sturrock et al, 2015 ) via seedling damping-off and crown rot ( Montealegre et al, 2010 ; Zamoum et al, 2017 ). A. solani can cause serious damage during all stages of plant growth ( Attia et al, 2020 ).…”