A group from International Centre for Genetic Engineering and Biotechnology, Trieste, Italy, etc. has reported on effects of Pseudomonas chlororaphis inoculation in Rice rhizosphere.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309335/
Among the group of Plant Growth-Promoting Rhizobacteria (PGPR), strains belonging to the Pseudomonas chlororaphis species have been found in association with a wide range of plants, both mono- and dicotyledonous, and both wild and cultivated. P. chlororaphis is currently classified into four subspecies, namely chlororaphis, aureofaciens, aurantiaca, and piscium. Several strains of P. chlororaphis have shown potential for application as plant probiotics due to their rhizosphere colonization abilities and plant-associated beneficial phenotypes such as chemotaxis and motility, biofilm formation, P solubilization, aminocyclopropane-1-carboxylic acid (ACC) deaminase, Indole-3-acetic acid (IAA) production and biocontrol.
P. chlororaphis strains produce different antifungal compounds such as Prn (pyrrolnitrin), PCN (phenazine-1-carboxamide), PCA (phenazine-1-carboxylic acid), 2-OH-PHZ (2-hydroxyphenazine), HPR (2-hexyl-5-propyl-alkylresorcinol) and HCN (hydrogen cyanide). These molecules inhibit the growth of various phytopathogens belonging to the Fusarium group and different species of Colletotrichum, Phytophthora, Pythium, Sclerotinia, Magnaporthe oryzae and Rhizoctonia, protecting plants.
In order to determine the effects of P. chlororaphis on plant growth, several phenotypic parameters were assayed. Statistical analyses were carried out on chlorophyll, flavonoid content and nitrogen balance index (NBI) as physiological parameters. In addition, plant height and dry shoot biomass at 90 days post inoculation (dpi) were also established. Results did not show any statistical differences between control and P. chlororaphis inoculated plants, although a tendency on higher NBI and lower flavonoid contents was measured in inoculated plants compared with the control. It was concluded that under the conditions tested, no significant plant beneficial effect was observed upon seed inoculation of P. chlororaphis.
However, there was a possibility that the plant defense system could be primed by P. chlororaphis maintaining a low level of stress.
In P. chlororaphis inoculated plants, it was found that expression of genes associated with defense OsISAP1, encoding for a multiple stress-responsive zinc-finger protein, was up-regulated at 28 dpi, suggesting an activation of the plant defense mechanisms.