Novel screening strategy reveals a potent Bacillus antagonist capable of mitigating wheat take-all disease caused by Gaeumannomyces graminis var. tritici

Abstract

Take-all, which is caused by the soilborne fungal pathogen Gaeumannomyces graminis var. tritici (Ggt), is one of the most widespread and devastating root diseases of wheat plants. This study focuses on a novel screening strategy of Bacillus isolates to evaluate their potential biological control capacity for suppressing wheat take-all. The joint assessment of antifungal activities, growth promotion factors and variety of antibiotic synthesis genes, in addition to greenhouse experiments, allowed for the identification and demonstration of the Bacillus isolate Pnf-12 as an effective disease control agent.

Inhibitory Abilities of Bacillus Isolates and Their Culture Filtrates against the Gray Mold Caused by Botrytis cinerea on Postharvest Fruit

“…Lipopeptide antibiotics have direct or indirect inhibitory effects on fungal plant pathogens, but they are not toxic to the plant itself (Ongena and Jacques, 2008; Zhang et al, 2017b). MALDI-TOF mass spectrometry can be easily and conveniently used for component identification (Sandrin et al, 2013; Xie et al, 2012).…”

“…Bacterial isolate RS-25 from jujube fruit, MG-4 from strawberry fruit, Z-14 from wheat rhizosphere soil and Pnf-4 from wheat plant significantly inhibited the growth of various phytopathogenic fungi and were maintained at 4°C on streak-inoculating nutritive agar (NA) slants (Zhang et al, 2017a, 2017b). The strains were cultured overnight at 37°C on NA slants, transferred to Erlenmeyer flasks containing 50 ml of the seed culture medium, and shaken at 220 rpm for 48 h at 37°C.…”

“…The filtrates were maintained overnight at 4°C and centrifuged to isolate the precipitate, which was then washed twice using diluted HCl (pH 2) and extracted twice using methanol (Zhang et al, 2017b). The extract was dried using a rotary vacuum evaporator and resuspended in an equivalent volume of sterile water to detect the biocontrol effects of the extract in controlling the gray mold caused by B. cinerea on postharvest fruit.…”

Effect of saponins of Quillaja saponaria extracts in combination with Pseudomonas protegens to control Gaeumannomyces graminis var. tritici in wheat

“…Take-all disease, caused by the ascomycete fungus G. graminis var. tritici (Ggt), causes severe losses in wheat (Triticum aestivum L.; Poaceae) crops in Chile (Andrade et al, 2011;Moya-Elizondo et al, 2015;Durán et al, 2017) and worldwide Yang et al, 2011;Zhang et al, 2017). This fungus triggers rotting and decomposition of the roots, crown, and basal culm of wheat plants and other cereals .…”

“…Despite great research efforts, a successful control of take-all disease has not yet been achieved Vera et al, 2014;Zhang et al, 2017). The majority of cultivated wheat varieties are susceptible to this disease (Vazvani et al, 2017), therefore its management is limited to selecting less susceptible varieties, balanced fertilization, crop rotation (Mathias-Ramwell et al, 2016), and the use of seed treatments with chemical fungicides Yang et al, 2014;Zhang et al, 2017).…”