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The plant–parasitic Root Knot Nematodes (Meloidogynespp.,) play a pivotal role to devastate vegetable crops across the globe. Considering the significance of plant–microbe interaction in the suppression of Root Knot Nematode, we investigated the diversity of microbiome associated with bioagents-treated and nematode-infected rhizosphere soil samples through metagenomics approach. The wide variety of organisms spread across different ecosystems showed the highest average abundance within each taxonomic level. In the rhizosphere, Proteobacteria, Firmicutes, and Actinobacteria were the dominant bacterial taxa, while Ascomycota, Basidiomycota, and Mucoromycota were prevalent among the fungal taxa. Regardless of the specific treatments, bacterial genera like Bacillus, Sphingomonas, and Pseudomonaswere consistently found in high abundance. Shannon diversity index vividly ensured that, bacterial communities were maximum in B. velezensisVB7-treated soil (1.4–2.4), followed by Root Knot Nematode-associated soils (1.3–2.2), whereas richness was higher with Trichoderma konigiopsisTK drenched soils (1.3–2.0). The predominant occurrence of fungal genera such as Aspergillus Epicoccum, Choanephora, Alternariaand Thanatephorushabituate rhizosphere soils. Shannon index expressed the abundant richness of fungal species in treated samples (1.04–0.90). Further, refraction and species diversity curve also depicted a significant increase with maximum diversity of fungal species in B. velezensisVB7-treated soil than T. koningiopsisand nematode-infested soil. In field trial, bioagents-treated tomato plant (60% reduction of Meloidogyne incognitainfection) had reduced gall index along with enhanced plant growth and increased fruit yield in comparison with the untreated plant. Hence, B. velezensisVB7 and T. koingiopsiscan be well explored as an antinemic bioagents against RKN.

Thirty-four Xanthomonas citripv. malvacearum(Xcm) isolates collected from three cotton-growing zones of India were subjected for virulence and race documentation and further correlated with genetic diversity as revealed by repetitive elements [repetitive extragenic palindromic (REP), enterobacterial repetitive intergenic consensus (ERIC) and BOX elements] and intersimple sequence repeat (ISSR)—PCR analyses. Among the 34 isolates tested for virulence on susceptible cultivar LRA 5166, 7 were recorded as highly virulent (HV), 16 were moderately virulent (MV) and 11 were less virulent (LV). Eight different races were recorded by using ten cotton host differentials. Twenty-two isolates (65%) belonged to race 18. Twelve isolates (35%) pertained to races 3, 5, 6, 7, 8, 11 and 13. REP, ERIC, BOX, combined repetitive elements, and ISSR analyses revealed the presence of 7, 10, 9, 11, and 8 clusters, respectively, at similarity coefficient of 0.70 in dendrograms. Principal coordinate analysis (PCoA) exhibited 76.4% and 77.5% cumulative variability for combined repetitive elements and ISSR analyses. ERIC produced the highest polymorphic information content (PIC) value (0.928). A lot of intra-pathovar variability was observed in virulence and genomic fingerprinting among Xcmisolates. Many of the isolates grouped based on geographical origin irrespective of virulence or race. The spread of the pathogen races in India might be due to the transport of germplasm lines and seed materials from one place to others.

We attempted to study the antibacterial activity of rhizospheric Bacillusspp., to curb the bacterial blight of anthurium caused by Xanthomonas axonopodispv. dieffenbachiae(Xad). Twenty-eight bacterial isolates from rhizospheric regions were identified as different Bacillusspp. and Ochrobactrumsp. using 16S rRNA gene sequencing. B. subtilisBIO3 effectively inhibited the growth of Xadup to 1450.7 mm2, and extracted volatile organic metabolites from the isolate BIO3 inhibited the growth of Xadup to 1024 mm2. Tritrophic interaction of anthurium leaves bacterized with B. subtilisBIO3 and challenged with Xadresulted in the expression of 12 unique proteins compared to untreated control. Mascot Peptide Mass Fingerprint-based identification indicated that one was glutathione peroxidase, involved in defence mechanism, other six proteins were identified as leghemoglobin II, CTP synthase-like, predicted protein (Physcomitrella patens), centromere-associated protein E, grain size protein, and five proteins were hypothetical proteins. Foliar application with 1% liquid formulations (108CFU/ml) of B. subtilisBIO3 significantly suppressed the bacterial leaf blight of anthurium up to 78% over untreated control and also increased the stem length and flower yield.