Evidence that the Biofungicide Serenade (Bacillus subtilis) Suppresses Clubroot on Canola via Antibiosis and Induced Host Resistance

Abstract

This study investigated how the timing of application of the biofungicide Serenade (Bacillus subtilis QST713) or it components (product filtrate and bacterial cell suspension) influenced infection of canola by Plasmodiophora brassicae under controlled conditions. The biofungicide and its components were applied as a soil drench at 5% concentration (vol/vol or equivalent CFU) to a planting mix infested with P. brassicae at seeding or at transplanting 7 or 14 days after seeding (DAS) to target primary and secondary zoospores of P. brassicae. Quantitative polymerase chain reaction (qPCR) was used to assess root colonization by B. subtilis as well as P. brassicae. The biofungicide was consistently more effective than the individual components in reducing infection by P. brassicae. Two applications were more effective than one, with the biofungicide suppressing infection completely and the individual components reducing clubroot severity by 62 to 83%. The biofungicide also reduced genomic DNA of P. brassicae in canola roots by 26 to 99% at 7 and 14 DAS, and the qPCR results were strongly correlated with root hair infection (%) assessed at the same time (r = 0.84 to 0.95). qPCR was also used to quantify the transcript activity of nine host-defense-related genes in inoculated plants treated with Serenade at 14 DAS for potential induced resistance. Genes encoding the jasmonic acid (BnOPR2), ethylene (BnACO), and phenylpropanoid (BnOPCL and BnCCR) pathways were upregulated by 2.2- to 23-fold in plants treated with the biofungicide relative to control plants. This induced defense response was translocated to the foliage (determined based on the inhibition of infection by Leptosphaeria maculans). It is possible that antibiosis and induced resistance are involved in clubroot suppression by Serenade. Activity against the infection from both primary and secondary zoospores of P. brassicae may be required for maximum efficacy against clubroot.

Plants and endophytes: equal partners in secondary metabolite production?

“…the fungal Acremonium or Heteroconium species (Joost 1995;Narisawa et al 2000;Jäschke et al 2010) or Bacillus subtilis that is already available as commercial product (Lahlali et al 2013). In some cases, the effect can be attributed to the production of toxins as in the Acremonium zeae/maize interaction (Poling et al 2008).…”

Influence of foliar sprays ofBacillus subtilisQST 713 on development of early blight disease and yield of field tomatoes in Ontario

“…Physical prevention of the pathogen or direct mode of action of biofungicide is only possible when the pathogen is in contact with biofungicide on the plant surface. Induction of plant resistance can be another possible mode of action of Serenade biofungicide (Lahlali et al 2013). The strain OTPB1 of B. subtilis has been specifically shown to enhance systemic resistance in tomato seedlings against the early blight pathogen through induction of growth hormones and defence enzymes (Chowdappa et al 2013).…”

“…(Jones et al 1991;Chaerani & Voorrips 2006). The first and most noticeable symptoms appear on the lower or older leaves as tiny dark brown spots soon after fruit set (Kucharek 2000). These spots enlarge in diameter and develop concentric or target-like rings often surrounded by a yellow halo.…”

“…Both formulations have been recently registered in Canada (under Health Canada registration numbers 28548 and 28626 for Serenade MAX and Serenade ASO, respectively) for use on various crops to control foliar diseases such as Botrytis blight, early blight, downy mildew, fire blight, powdery mildew and white mould. Recently, the biofungicide B. subtilis QST 713 has also been assayed for the control of clubroot on canola (Lahlali et al 2013). However, a multi-year study showing the impact of this biofungicide on the development of early blight of tomato under field conditions has not been undertaken.…”

Eco-Friendly Management of Chilli Anthracnose (Colletotrichum capsici)

“…Use of plant extracts like neem (Azadirachta indica), mahogany (Swietenia mahagoni), koromcha (Carissa carandas), garlic (Allium sativum), zinzer (Zingiber officinale), marigold (Tagetes erecta), allamonda (Allamonda cathertica) etc. (Ashrafuzzaman and Khan, 1992;Freeman et al, 2001;Rashid et al, 2007Rashid et al, , 2010Masuduzzaman et al, 2008;Amin et al, 2009;Perello et al, 2013a,b;Kabir et al, 2014) and the use of bio-fungicide Trichoderma spp., Bacillus subtilis (Moretto et al, 2001;Verma et al, 2007;Boonratkwang et al, 2007;Lahlali et al, 2013;Fitsum et al, 2014) might be useful in controlling different fungal diseases of various agricultural crops. The effect of certain plant extracts on the management of some diseases of chilli such as dieback, fruit rot and anthracnose were reported.…”