Biocontrol of black foot disease on grapevine rootstocks using Bacillus subtilis strain F62

Abstract

Decline and death of young vines is a worldwide problem for viticulture that may lead to economic loss. Fungal pathogens have been associated with trunk and root diseases, including the black foot disease that affects the performance of the vineyards. Fungicides have not worked efficiently to control the disease and alternative methods should be investigated. We evaluated the potential of Bacillus subtilis strain F62 for controlling the disease caused by different strains in grapevine rootstocks 1103P (Vitis berlandieri × V. rupestris) and SO4 (V. berlandieri × V. riparia). The in vitro antagonism of B. subtilis F62 was evaluated on mycelial growth, by diffusible and volatile compounds, and conidia germination, by bacterial suspension and cell-free filtrate. In the in vivo assay, cuttings and micropropagated rootstocks were submitted to four different treatments: control, Bac (B. subtilis inoculation), Pat (pathogen inoculation) and Bac + Pat. According to our results, the bioagent was able to inhibit the mycelial growth of all the three fungal isolates by diffusible compounds and conidial germination by bacterial suspension and cell-free filtrate. In the in vivo assay, cuttings of SO4 treated with B. subtilis F62 showed higher shoot nodes and length of primary shoot, while cuttings of 1103P had a longer primary shoot. In micropropagated plants, B. subtilis F62 promoted plant growth in both rootstocks and reduced the frequency of D. macrodidyma re-isolation to 24.6% in SO4 and 29.5% in 1103P. The results demonstrated the potential of B. subtilis F62 on plant growth promotion and in the biocontrol of black foot disease on micropropagated plants and cuttings of grapevine rootstocks 1103P and SO4.

Mycorrhizal symbiosis balances rootstock-mediated growth-defence tradeoffs

“…Pseudomonas genus was studied for its ability to impair Botrytis, Neofusiccocum, Ilyonectria, Aspergillus, Phaeomoniella and Phaeoacremonium genera, which are all well-known grape fungal pathogens (Andreolli et al 2019;Niem et al 2020). On the other hand, Bacillus species were studied for their ability to reduce the impact of black foot disease (mainly due to infection by Cylindrocarpon and Ilyonectria species) and downy mildew on grapes (Zhang et al 2017;Russi et al 2020). These studies well fit with our data where we observed the lower Ilyonectria abundance in M+I 1103P and concomitantly the higher abundance of Bacillus species.…”

The efficacy of 8‐hydroxyquinoline derivatives in controlling the fungusIlyonectria liriodendri, the causative agent of black foot disease in grapevines

“…Santos et al (2013), concluded that chitosan (TecnifolâDefender) and diphenoconazole showed promising results in in vitro tests in controlling I. liriodendri. Russi et al (2020), evaluated the antifungal activity of an F62 strain of Bacillus subtilis against the TD 176 and 1117 strains of I. liriodendri and found that this agent reduced mycelial growth by 69Á7 and 69%, respectively. Santos et al (2016) also saw a reduction in the growth inhibition of Dactylonectria macrodidyma, in trials of commercial products containing B. subtilis.…”

“…Due to the low effectiveness of fungicides on the causative agents of this disease, alternative control methods have recently been tested, such as chitosan-based products (Santos et al 2013) and biocontrol agents such as Trichoderma sp. and Bacillus subtilis (Halleen et al 2007;Santos et al 2016;Russi et al 2020). The ideal approach would be to protect wounds, in order to avoid infection in the adult plants.…”

The Grapevine Microbiome to the Rescue: Implications for the Biocontrol of Trunk Diseases

“…macrodidyma (involved in black foot disease) when inoculated on grapevine plants. This strain is defined by the authors as a soil-borne strain, but no data regarding a putative isolation from grapevine microbiome are indicated [ 87 ]. However, the B. subtilis PTA-271 strain was isolated from the rhizosphere of healthy Chardonnay grapevines from a vineyard located in the Champagne area (France) [ 82 ] ( Table 2 ).…”