<p dir="ltr">Plant-associated endophytes offer promising agricultural, environmental, and biotechnological applications. Despite their potential utility, difficulties in culturing these microorganisms under laboratory conditions have limited both their isolation and a comprehensive understanding of their biology, function, and ecological role. Against this background, <i>Pseudomonas granadensis </i>strain CT364 - isolated from the olive tree rhizosphere – emerged as a potential endophyte of interest due to its cultivability and its ability to promote rooting across diverse species, including olive trees, rapeseed, mung bean and cowpea.</p><p dir="ltr">Genome annotation and <i>in silico</i> predictions identified 564 genes linked to rhizosphere competence, plant colonisation and plant growth-promoting traits. Experimental findings confirmed the strain’s motility, capacity for biofilm formation, and ability to sense and respond to plant-derived signals. <i>P. granadensis</i> CT364 effectively colonises the rhizosphere, rhizoplane, and internal tissues of Arabidopsis, confirming its endophytic nature without exhibiting any pathogenic traits. Inoculation experiments demonstrated significant effects on root architecture and increases in plant biomass and rosette area. Notably, these benefits were retained under salinity and osmotic stress, underscoring its plant growth-promoting ability. Finally, both genome analysis and experimental tests confirmed its resistance to osmotic stress and heavy metal toxicity, highlighting the strain’s ability to survive in difficult environments.</p><p dir="ltr">The integration of genomic insights and experimental validation supports the conclusion that <i>P. granadensis</i> CT364 is a plant growth-promoting endophytic bacterium. Its ability to enhance plant development under both optimal and stressful conditions, combined with its ability to colonise Arabidopsis and non-pathogenic nature, positions this strain as a potential bioinoculant for sustainable agriculture. Furthermore, the identification of specific genes related to plant sensing and colonisation, and its genetic tractability, open avenues for exploring underlying mechanisms of plant–microbe interactions. In summary, <i>P. granadensis</i> CT364 therefore not only holds potential for improving crop performance under challenging environmental conditions but also offers a valuable model for the study of beneficial plant–bacterial symbiosis.</p><p dir="ltr">This data collection contains the raw data underpinning the following figures:</p><ul><li>Fig 1C (biofilm formation in the presence of root exudates collected from 14-, 18- and 21-day-old Arabidopsis plants. Specific Biofilm Formation (SBF) was calculated by crystal violet staining following 4 h incubation. The assay was conducted with three biological replicates)</li><li>Fig 5B (measurements of Arabidopsis fresh weight, rosette dry weight and rosette area following inoculation with <i>P. granadensis</i> CT364. Plants were sown in 1/2 MS agar plates for a week before seedlings were transferred to Jiffy pellets and inoculated with either MgSO4 (Mock) or <i>P. granadensis</i> CT364 suspension. Plants were grown for a total of 28 days with watering every three days. Salinity was simulated by single irrigation with a 100 mM NaCl solution one week after inoculation.</li><li>Fig S1 (<i>P. granadensis</i> CT364 growth under saline and osmotic stress simulated conditions, by the addition of NaCl or PEG respectively. The strain was cultured in TSB with varying water potentials from 0 (C+) to -4 MPa. Non-inoculated TSB was used as a negative control (C-). Growth curves were obtained by cell turbidity monitorisation in a plate reader (λ=600 nm) for 60 hours. The experiment was performed in triplicate.</li><li>Fig S4 (<i>P. granadensis</i> CT364 growth in different concentrations of heavy metals).</li></ul><p><br></p>
Funding
NLD (Newcastle-Liverpool-Durham) Doctoral Training Partnership 3
Biotechnology and Biological Sciences Research Council