Abstract
Aim: This study aimed to isolate, characterize and assess the plant growth-promoting traits of bacterial isolates inhabiting the rhizosphere of Solanum lycopersicum L. (tomato) against three plants-Eruca sativa, Lepidium sativum and Raphanus sativum-from Saudi Arabia's AI-Ahsa region.
Methodology: A bacterial isolate designated as SLK10 was obtained from the rhizosphere of tomato grown in the AI-Ahsa region, Saudi Arabia. SLK10 was further characterized morphologically, biochemically and genotypically using 16S rRNA gene sequencing. The roles in alleviating salt stress effects on three important economic crops were also assessed by implementing a cross-inoculation strategy.
Results: SLK10 formed a circular, non-pigmented and raised colony with an entire margin. The cells were rod shaped and Gram negative. SLK10 displayed multiple plant growth-stimulating features, such as the solubilization of inorganic phosphate and the production of phytohormones and acetoin. Comparative sequence analysis of 16S rRNA gene revealed that SLK10 belonged to Pseudomonas monteilii, to which it exhibited 99.86% sequence homology. SLK10 significantly promoted the length of primary root, stem and number of leaves in Eruca sativa, Lepidium sativumand Raphanus sativus growing under 1000 ppm salt stress. The number of leaves in L. sativum and R. sativus growing under 2000 ppm salt stress was substantially enhanced by SLK10.
Interpretation: SLK10 is a plant growth-promoting bacterium and can be used as a green fertilizer to increase soil fertility and plant productivity in the Eastern region of Saudi Arabia.