Pseudomonas aeruginosa isolate PM1 effectively controls virus infection and promotes growth in plants

A bacterial isolate PM1 obtained from the rhizosphere of healthy plants was identified as Pseudomonas aeruginosa by biochemical characteristics and 16S rRNA gene sequence (GenBank ID OL321133.1). It induced resistance in Nicotiana tabacum cv. Xanthi-nc and Cyamopsis tetragonoloba, against Tobacco mosaic virus (TMV) and Sunn-hemp rosette virus (SRV), respectively. Foliar treatment with isolate PM1 curbed TMV accumulation in susceptible N. tabacum cv. White Burley. PM1 was more effective as a foliar than a root/soil drench treatment, evident through a comparative decrease in ELISA values, and reduced viral RNA accumulation. Foliar and soil drench treatment with PM1 resulted in a disease index of 48 and 86 per cent, and a control rate of 48.9 and 8.5 per cent, respectively. PM1 exhibited phosphate solubilization, produced siderophores, auxins, HCN, and ammonia, all important plant growth-promoting traits. Foliar treatment with PM1 enhanced growth in tobacco, while its volatiles significantly promoted seedling growth in C. tetragonoloba. Of the several metabolites produced by the isolate, many are known contributors to induction of systemic resistance, antibiosis, and growth promotion in plants. Soluble metabolites of PM1 were less effective in inducing antiviral resistance in N. tabacum cv. Xanthi-nc in comparison with its broth culture. PM1 and its metabolites were antagonistic to Gram-positive Bacillus spizizenii and Staphylococcus aureus, and fungi Fusarium oxysporum, Aspergillus niger, and Rhizopus stolonifer. Its volatiles were inhibitory to F. oxysporum and R. stolonifer. Thus, PM1 exhibited considerable potential for further evaluation in plant virus control and production of diverse metabolites of use in agriculture and medicine.