Bipolaris sorokiniana is a pathogen of cereals, such as wheat (Triticum turgidum) and barley (Hordeum vulgare), causing root rot, leaf blight, seedling blight, and spot blotch. This disease affects seed germination and seedling emergence, generating a considerable reduction in yield of up to 85% (^{Mehta, 2014}). Currently, disease management against B. sorokiniana is carried out through the foliar application of ergosterol biosynthesis disruptors from the triazole group, despite these being reported with harmful effects, such as soil contamination, inhibition of non-target organisms, and human cytotoxicity (^{Villa-Rodríguez et al., 2019}). In addition, this is strategy not only toxic to humans but also harmful to the environment and results in an imbalance within the soil microbial community and a rapid increase in the spread of resistance genes (^{Ahmad et al., 2018}). Thus, sustainable alternatives to the application of synthetic fungicides are determinants for the control of phytopathogens, such as the application of biological control agents.

Currently, the most studied, produced, and commercialized bacterial biological control agents are the Bacillus species, due to its high efficacy, safety, and ability to form spores, allowing it to prevail in most agroecosystems (^{Villareal-Delgado et al., 2018}; ^{Córdova-Albores et al., 2020}). Thus, this study aims to identify the potential biocontrol mechanisms of the bacterial strain TSO2 by sequencing, annotation, and mining its genome to explore the use of this strain for biopesticides formulation.

In this way, strain TSO2 was isolated from the soil where durum wheat was planted commercially, in the Yaqui Valley, Mexico (27.3692°, 110.3886°), using a serial dilution method in Nutrient Agar (NA) culture medium at 28 °C for 2 days (^{Valenzuela-Aragon et al., 2018}). After bacterial purification, this strain was cryopreserved, at -80 °C by using Nutrient Broth (NB) culture medium supplemented with 30% glycerol, in the Colección de Microorganismos Edáficos y Endófitos Nativos (COLMENA) (^{de los Santos-Villalobos et al., 2018}; de los Santos-Villalobos et al., 2021). After purification, an agar plug of 0.5 cm diameter of Bipolaris sorokiniana TPQ3 mycelia was placed in the center of a Petri dish containing Potato Dextrose Agar (PDA), and strain TSO2 was inoculated at four equidistant points by triplicate around the phytopathogen and incubated for five days at 28 °C. Thus, strain TSO2 showed great biocontrol activity against B. sorokiniana TPQ3, inhibition zone of 8.0 ± 0.2 mm, through the production of extracellular diffusible compounds with strong antifungal activity, and cytotoxic activity (^{Villa-Rodríguez et al., 2019}).

Based on these findings, strain TSO2 was sequenced to further explore potential biocontrol mechanisms. High-quality genomic DNA was extracted from a fresh culture of this strain grown in NB [24 h at 32 °C, using an orbital shaker at 121 rpm, obtaining 1×10⁶ Colony Forming Units (CFU) mL^-1], and following the protocol described by ^{Valenzuela-Aragon et al. (2018}). Then, the bacterial DNA was sequenced by the Illumina MiSeq platform, obtaining a total of 3,584,209 total pair-end reads [2 x 300 base pairs (bp)]. The quality of the obtained reads was analyzed by FastQC version 0.11.5 (^{Andrews, 2010}). Trimmomatic version 0.32 (^{Bolger et al., 2014}) was used to remove adapter sequences and low-quality bases, only 7.39% was dropped. Subsequently, de novo assembly was generated by SPAdes version 3.14.1 (^{Bankevich et al., 2012}), using the “--careful” parameter for error correction in reads. The assembled contigs were ordered by Mauve contig Mover version 2.4.0 (^{Darling et al., 2004}), using the reference genome of Bacillus cabrialesii TE3^T (Genebank accession number GCA_004124315.1) (^{de los Santos Villalobos et al., 2019}), based on the highest similarity of the 16S rRNA gene, with 100% similarity and 100% completeness (Figure 1). In addition, plasmid detection was carried out by PlasmidFinder 2.0 (^{Carattoli et al., 2014}), where no plasmids were detected. Thus, the draft genome of strain TSO2 presented 4,242,212 bp; 43.9% G+C content; 300,069 bp N50; 5 L50; and 47 contigs (> 200bp).

The genome annotation of the studied strain was created through Rapid Annotation using Subsystem Technology (RAST) server version 2.0 (http://rast.nmpdr.org) (^{Overbeek et al., 2013}), by the default RASTtk pipeline (Figure 2). Thus, strain TSO2 showed a total of 96 RNAs and 4,432 predicted coding DNA sequences (CDS) distributed into 328 subsystems. The most abundant subsystem was amino acids and derivatives (307 CDS), followed by carbohydrates (252 CDS). This genome showed the presence of agricultural importance genes involved in i) virulence, disease, and defense (34 CDS), which include bacitracin stress response (7 CDS), resistance to antibiotics and toxic compounds (15 CDS), and invasion and intracellular resistance (12 CDS); and ii) iron acquisition and metabolism (30 CDS), including siderophores Bacillibactin (10 CDS) and Anthrachelin (5 CDS).

Figure 1 Phylogenetic Tree. Phylogenetic relation between strain TSO2 and closely related species: Bacillus inaquosorum KCTC 13429T (AMXN01000021); B. cabrialesii TE3T (MK462260); B. spizizenii NRRL B-23049T (CP002905); B. tequilensis KCTC13622T (AYTO0100004); B. stercoris JCM 30051T (MN536904); B. subtilis NCIB 3610T (ABQL01000001); B. halotolerans ATCC 25096T (LPVF01000003); B. mojavensis RO-H-1T (JH600280); B. vallismortis DV1-F-3T (JH600273); B. nakamurai NRRL B-41091T (JH600273); B. velezensis CR-502T (AY603658); B. amyloliquefaciens DSM 7T (FN597644); B. siamensis KCTC13613T (AJVF01000043); B. atrophaeus JCM 9070T (AB021181); B. glycinifermentans GO-13T (LECW01000063); B.paralicheniformis KJ-16 T (KY694465), constructed by CLC Sequence Viewer v8.0.0 (CLC bio A/S, Qiagen, Denmark) using the neighbor-joining algorithm (based on 1000 bootstrap replications). Scale bar (0.006) represents the number of nucleotide substitutions per site. 

Figure 2 Coding sequences subsystem distribution from strain TSO2 generated through RASTtk pipeline. CDS: 4432, CDS in subsystems: 1204, and subsystems: 328. 

Besides, the circular chromosome map was generated using the CGView Server (^{Grant and Stothard 2008}) (Figure 3). In addition, using antiSMASH 5.2.0 under default parameters (^{Blin et al., 2021}), seven putative Biosynthetic Gene Clusters (BGC) were identified in the genome of strain TSO2 (Figure 3). For example i) Fengycin (100%), which is a lipopeptide with strong fungitoxic activity against filamentous fungi (^{Koumoutsi et al., 2004}); ii) Bacilysin (100%), a dipeptide with an impressively broad range of antagonistic activity against fungi and bacteria (^{Nannan et al., 2021}); iii) Subtilosin A (100%), a bacteriocin ribosomally produced with potent antimicrobial property (^{Ezrari et al., 2021}); iv) Bacillibactin (100%), an archetypal triscatetholate siderophore known for its highest affinity for iron (Fe³⁺) of natural siderophores (^{Nithyapriya et al., 2021}); v) Bacillaene (100%), a polyketide which has an important biological role associated as antibiotic weapons for Bacillus to resist other environmental microbes (^{Li et al., 2021}); vi) Killing factor (100%), a peptide that induces the lysis of sibling no-sporulated and non-exogenous toxin resistant cells for nutrient resource, this providing the species a favorable trait in regards to sporulation, and hence competence in the niche (^{González-Pastor, 2010}); and vii) Surfactin (86%), which is a powerful lipopeptide biosurfactant and a versatile bioactive molecule that has demonstrated antifungal, antiviral, antitumor, insecticide, antimycoplasma, and bioremediation agents in soil and water (^{Mulligan, 2005}).

Figure 3 Circular Chromosome Map of Bacillus sp. strain TSO2, distribution of coding DNA sequences (CDS), tRNAs, rRNAs, and GC content skew (50% of the total base-pair window), as well as the Biosynthetic Gene Clusters (BGC) identified through antiSMASH. 

Bacillus sp. strain TSO2 contains a great number of Biosynthetic Gene Clusters (BGC) which support its biocontrol activity against phytopathogenic fungi. Thus, this strain needs to be further studied as a potential bioactive ingredient for the biopesticides formulation due to its high potential as a biological control agent by the secretion of antibiotics and antimicrobial peptides, and the production of siderophores.

Data availability. This draft genome sequence has been deposited in DDBJ/ENA/ GenBank under accession number JAHBMK000000000. The version described in this paper is the first version, JAHBMK000000000, under BioProject number PRJNA728132 and BioSample number SAMN19070894. Raw data is available under accession number SRR16775344.