The root-knot nematode (RKN), Meloidogyne javanica, causes severe damage to a wide variety of crops. These nematodes significantly reduce tomato yield globally, causing symptoms such as stunted growth, galls on roots, chlorosis, and wilting, ultimately leading to host death. Classical nematode control methods, such as the application of chemical nematicides, are very effective; however, their use is limited due to conflicts with sustainable agriculture. Therefore, biological methods, are gaining attention as more environmentally friendly options. In the present study, 47 strains of bacteria were isolated from the rhizosphere of RKN-infected plants. The effect of these strains was studied on egg hatching and second stage infective juveniles (J2s) mortality of M. javanica, in vitro. Then, three holes were made in the soil around the roots of non-inoculated and nematode inoculated tomato plants and a suspension of 15 mL of three isolates with the greatest negative effect on hatching and J2s mortality (107 CFU/ml), was poured into the holes. Stenotrophomonas maltophilia CPHE1, Peribacillus frigoritolerans Rhs-L31 and Bacillus cereus Pt0-RL12 improved the vegetative indices of inoculated plants compared to control plants. These strains significantly reduced nematode hatching and significantly increased mortality of nematode J2s; and in greenhouse pot experiments significantly reduced the number of nematode eggs and egg masses, root galls, and nematode reproduction factor. In each case, inoculation with the bacterial strains significantly increased peroxidase and superoxide dismutase activity, and decreased catalase activity in tomato roots infected with M. javanica. The present study indicates the potential of these bacterial strains for biocontrol of M. javanica on tomato.

In recent years, the effects of fluoride (F) pollution in numerous ecosystems such as groundwater, soil, etc. Have become a major issue worldwide. This increase in F pollution is a direct consequence of the unbridled use of fertilizers in agricultural and several other human activities that require immediate and appropriate action. Therefore, this manuscript reveals important findings on the efficacy of bacteria isolated from agricultural fields in central Chhattisgarh in manifesting resistance to F and in reversing the F-induced oxidative damage in susceptible Oryza sativa L, (Var. MTU1010). Chronic exposure of Oryza sativa L. to sodium fluoride (NaF) (50 mg L- 1) severely impeded growth and various physiological parameters such as germination percentage, biomass and root and shoot length and stimulated the formation of reactive oxygen species (ROS), which enhanced electrolyte leakage and formation of cytotoxic products like malondialdehyde. To this end, potential bacterial strains, namely MT2A, MT3A, MT4A, and Du3A were isolated, screened for various plant growth promoting (PGP) traits and used to explore their efficiency to mitigate F toxicity in Oryza sativa L. in vivo. The seedlings inoculated with the bacterial strains showed significant development as evidenced by an increase in root and shoot length, biomass and chlorophyll content. Additionally, inoculation of these strains in combination with F stress significantly decreased oxidative stress by increasing the expression of protective genes encoding antioxidant enzymes and boosted agronomic traits remarkably. Overall, the manuscript demonstrates the pivotal role played by the isolated bacteria in abating ill effects of F in the Oryza sativa L. seedlings and proves their potential as protective bioagents against F stress.

High soil salinity has an unfavorable consequence on the growth and productivity of rice crop. However, some salt-tolerant plant growth-promoting bacteria (ST-PGPB) regulate specific physiological, biochemical, and molecular properties to promote crop growth while minimizing the detrimental effects of salt stress. In this regard, we isolated ST-PGPB from rhizospheric soil and examined it to mitigate the salinity stress in rice seedlings. The growth of the bacterium at 3 M NaCl demonstrated its halotolerance, and 16S rRNA sequencing identified it as Bacillus siamensis, and the isolated strain was named BW. Further study indicated that biopriming with BW strain helps plant growth promotion-related phenotype and significantly mitigates salinity stress in rice seedlings. Treatment of rice seeds with BW resulted in significantly improved germination of seedlings at 75 mM to 150 mM NaCl, along with better physiology and biochemical parameters than the untreated ones. Furthermore, Bacillus sp. BW efficiently colonizes rice roots and produces auxin and siderophore, via forming biofilm under different salt concentrations. Under 100-200 mM NaCl treatment conditions, the extracellular metabolite profile from BW showed a substantial abundance in specific metabolites, such as osmoprotective chemicals, suggesting the likely protective mechanism against salinity stress damage. This study demonstrates the role and potential of a halotolerant- BW strain in supporting the growth of rice plants under salinity conditions.