Grapevine trunk diseases (GTDs) are a big threat for global viticulture. Without effective chemicals, biocontrol strategies are developed as alternatives to better cope with environmental concerns. A combination of biological control agents (BCAs) could even improve sustainable disease management through complementary ways of protection. In this study, we evaluated the combination of Bacillus subtilis (Bs) PTA-271 and Trichoderma atroviride (Ta) SC1 for the protection of Chardonnay and Tempranillo rootlings against Neofusicoccum parvum Bt67, an aggressive pathogen associated to Botryosphaeria dieback (BD). Indirect benefits offered by each BCA and their combination were then characterized in planta, as well as their direct benefits in vitro. Results provide evidence that (1) the cultivar contributes to the beneficial effects of Bs PTA-271 and Ta SC1 against N. parvum, and that (2) the in vitro BCA mutual antagonism switches to the strongest fungistatic effect toward Np-Bt67 in a three-way confrontation test. We also report for the first time the beneficial potential of a combination of BCA against Np-Bt67 especially in Tempranillo. Our findings highlight a common feature for both cultivars: salicylic acid (SA)-dependent defenses were strongly decreased in plants protected by the BCA, in contrast with symptomatic ones. We thus suggest that (1) the high basal expression of SA-dependent defenses in Tempranillo explains its highest susceptibility to N. parvum, and that (2) the cultivar-specific responses to the beneficial Bs PTA-271 and Ta SC1 remain to be further investigated.

Background: Bacillus subtilis strains have been widely studied for their numerous benefits in agriculture, including viticulture. Providing several assets, B. subtilis spp. are described as promising plant-protectors against many pathogens and as influencers to adaptations in a changing environment. This study reports the draft genome sequence of the beneficial Bacillus subtilis PTA-271, isolated from the rhizospheric soil of healthy Vitis vinifera cv. Chardonnay at Champagne Region in France, attempting to draw outlines of its full biocontrol capacity.Results: The PTA-271 genome has a size of 4,001,755 bp, with 43.78% of G + C content and 3,945 protein coding genes. The draft genome of PTA-271 putatively highlights a functional swarming motility system hypothesizing a colonizing capacity and a strong interacting capacity, strong survival capacities and a set of genes encoding for bioactive substances. Predicted bioactive compounds are known to: stimulate plant growth or defenses such as hormones and elicitors, influence beneficial microbiota, and counteract pathogen aggressiveness such as effectors and many kinds of detoxifying enzymes.Conclusions: Plurality of the putatively encoded biomolecules by Bacillus subtilis PTA-271 genome suggests environmentally robust biocontrol potential of PTA-271, protecting plants against a broad spectrum of pathogens.

Background Bacillus subtilis strains have been widely studied for their numerous benefits in agriculture, including viticulture. Providing several assets, B. subtilis spp. are described as promising plant-protectors against many pathogens and as influencers to adaptations in a changing environment. This study reports the draft genome sequence of the beneficial Bacillus subtilis PTA-271, isolated from the rhizospheric soil of healthy Vitis vinifera cv. Chardonnay at Champagne Region in France, attempting to draw outlines of its full biocontrol capacity. Results The PTA-271 genome has a size of 4,001,755 bp, with 43.78% of G + C content and 3945 protein coding genes. The draft genome of PTA-271 putatively highlights a functional swarming motility system hypothesizing a colonizing capacity and a strong interacting capacity, strong survival capacities and a set of genes encoding for bioactive substances. Predicted bioactive compounds are known to: stimulate plant growth or defenses such as hormones and elicitors, influence beneficial microbiota, and counteract pathogen aggressiveness such as effectors and many kinds of detoxifying enzymes. Conclusions Plurality of the putatively encoded biomolecules by Bacillus subtilis PTA-271 genome suggests environmentally robust biocontrol potential of PTA-271, protecting plants against a broad spectrum of pathogens.

Background: Grapevine trunk diseases (GTDs) are a complex group of diseases that lead to major economic losses in all wine-producing countries. The investigation of biocontrol agents (BCAs) capable of forestalling or at least minimizing the development of GTDs has, recently, become a priority. Nursery experiments were set up to (i) assess the biocontrol effect of Trichoderma atroviride (Ta) SC1 and Bacillus subtilis (Bs) PTA-271, alone and in simultaneous application, against Botryosphaeria dieback (BOT)-and black-foot (BF)-associated pathogens during the grapevine propagation process and (ii) evaluate the success of the BCA inoculation during the grapevine propagation process, using quantitative reversetranscription polymerase chain reaction techniques. RESULTS:The results demonstrated a significant reduction in the percentage of potentially infected plants and the percentage of fungal isolation from wood fragments of BOT and BF pathogens in nursery material treated with Ta SC1 and Bs PTA-271, respectively. In one of the experiments, simultaneous treatments with Bs PTA-271 and Ta SC1 caused a reduction in percentages of potentially infected plants and fungal isolation, from wood fragments containing BOT and BF pathogens.CONCLUSION: These biological treatments may be relevant components of an integrated approach, using complementary management strategies to limit infection by GTD pathogens, but further research is still needed to elucidate the effectiveness of Bs PTA-271 and the benefits of simultaneous application with Ta SC1 for the control of GTD pathogens in nurseries.

Two Neofusicoccumparvum isolates and a UV mutant were characterized for their phytotoxin production in vitro, their pathogenicity on grapevine, and their genome sequenced. The isolate Np-Bt67 produced high level of (-)-terremutin, but almost no (R)-mellein, and it was the most aggressive on grapevine, triggering apoplexy. Similar symptoms were not induced by purified (-)-terremutin. The isolate Bourgogne S-116 (Np-B) produced 3-fold less (-)-terremutin and high amounts of (R)-mellein, but it was less aggressive on grapevine than Np-Bt67. The UV9 mutant obtained from Np-B (NpB-UV9) no longer produced (-)-terremutin but overproduced (R)-mellein by 2.5-fold, and it was as pathogenic as its parent. NpB-UV9 differed from its parent by simple mutations in two genes (transcription factor UCR-NP2_6692, regulatory protein UCR-NP2_9007), not located neither near (R)-mellein, nor (-)-terremutin biosynthetic genes, but likely involved in the control of (-)-terremutin biosynthesis. Grapevine immunity was disturbed upon challenge with these pathogens or purified phytotoxins, leading to an upregulation of SA-dependent defenses, while (-)-terremutin interfered with host JA/ET-dependent defenses. Our results suggest that neither (-)-terremutin nor (R)-mellein alone is essential for the pathogenicity of N. parvum on grapevine, since isolate/mutant non-producing these toxins in vitro is pathogenic. However, these phytotoxins could play a quantitative role in the infection process.

Background Without effective chemical treatments, there is an increased interest on biological control of plant diseases. Trichoderma and Bacillus species have shown biocontrol potential against several grapevine diseases. However, few studies have investigated the impact of introducing beneficial microorganisms in rhizosphere, on the indigenous soil existent microbiome. Plant-associated microbiomes are complex, and there is a limited knowledge of the mechanisms that maintain and stimulate specific plant-associated microbial communities. In this study, we tested the hypothesis that the introduction of the biological control agents (BCAs) Bacillus subtilis PTA-271 (Bs PTA-271) and Trichoderma atroviride SC1 (Ta SC1) produce distinctive modifications in the composition and co-occurrence network structure of the grapevine rhizosphere microbial community, as well as grapevine induced defenses. Results Our results demonstrated that, the fungal microbiome is more affected by factors such as soil type, BCA treatment, and sampling time than bacterial microbiome. Specifically, Ta SC1 application produced a negative impact on fungal diversity, while applications of BCAs did not affect bacterial diversity. Interestingly, the survival and establishment of both BCAs showed opposite trends depending on the soil type, indicating that the physicochemical properties of soils have a role on BCA establishment. Fungal co-occurrence networks were less complex than bacterial networks, but highly impacted by Ta SC1 application. Soils treated with Ta SC1, presented more complex and stable co-occurrence networks, with a higher number of positive correlations. Induced grapevine defenses also differed according to the soil, being more affected by BCA inoculation on sandy soil. Conclusions The findings of this research emphasize the complex relationships among microorganisms in the rhizosphere, and point to the impact of biocontrol treatments on fungal and bacterial rhizosphere microbiomes. It highlights the significance of taking into account various factors like soil type, sampling time, and BCA treatment, and their influence on the structure and dynamics of microbial communities. In the future, it is crucial to conduct additional studies to explore these microbial interactions in greater detail, with the goal of developing more precise and efficient biocontrol strategies for agriculture.

Background: Bacillus subtilis strains have been widely studied for their innumerous benefits in agriculture, including viticulture. Providing numerous assets, B. subtilis spp. are described as promising plant-protectors against many pathogens and as influencers to adaptations in a changing environment. This study reports the draft genome sequence of the beneficial Bacillus subtilis PTA-271, isolated from the rhizospheric soil of healthy Vitis vinifera cv. Chardonnay at Champagne Region in France, attempting to draw outlines of its full biocontrol capacity.Results: The PTA-271 genome has a size of 4,001,755 bp, with 43.78% of G + C content and 3,945 protein coding genes. The draft genome of PTA-271 putatively highlights a functional swarming motility system hypothesizing a colonizing capacity and a strong interacting capacity, strong survival capacities and a set of genes encoding for bioactive substances. Predicted bioactive compounds are known both to: stimulate plant growth or defenses such as hormones and elicitors, influence beneficial microbiota, and counteract pathogen aggressiveness such as effectors and many kinds of detoxifying enzymes.Conclusions: Plurality of the putatively encoded biomolecules by Bacillus subtilis PTA-271 genome appears as strengths for PTA-271 biocontrol potential towards plants, highlighting a big potential against a broad spectrum of pathogens whatever environmental constraints.

Background: Bacillus subtilis strains have been widely studied for their innumerous benefits in agriculture, including viticulture. Providing numerous assets, B. subtilis spp. are widely described as promising grapevine-protectors against a broad spectrum of pathogens, ranging from biotroph to necrotroph. B. subtilis spp. may both elicit host defenses and promote host vigor, but may also directly antagonize pathogens and detoxify their aggressive molecules. This study reports the draft genome sequence of the Bacillus subtilis PTA-271, isolated from the rhizospheric soil of healthy Vitis vinifera cv. Chardonnay at Champagne Region in France, attempting to draw outlines of its full biocontrol capacity. Results: The PTA-271 genome has a size of 4,001,755 bp, with 43.78% of G + C content and 3,945 protein coding genes. The draft genome of PTA-271 highlights (1) a functional swarming motility system hypothesizing a colonizing capacity and a strong interacting capacity, (2) strong survival capacities and (3) a set of genes encoding for bioactive substances. Bioactive compounds are known both (i) to stimulate plant growth or defenses such as hormones and elicitors, and (ii) to counteract pathogen aggressiveness such as effectors and many kinds of detoxifying enzymes.Conclusions: The plurality of the encoded biomolecules by Bacillus subtilis PTA-271 genome appears as strengths for PTA-271 biocontrol potential towards plants, offering a big potential against a broad spectrum of pathogens, especially those responsible for the complex grapevine trunk diseases.