Morpho-molecular and Biochemical Characterization of Pseudomonas spp. Associated with Brinjal (Solanum melongena L.) Rhizosphere in Southern India

Abstract

The present study aimed to isolate and characterize rhizosphere-associated Pseudomonas spp. from brinjal (Solanum melongena L.) growing regions of Tamil Nadu and Andhra Pradesh, India, Morphological characterization revealed uniform colony morphology, biochemical, and molecular diversity. A systematic survey conducted during 2023–2024 yielded twenty fluorescent Pseudomonas isolates (AUPI-1 to AUPI- 20) from both healthy and wilt-affected brinjal fields, representing diverse agro-climatic zones. Morphological characterization revealed largely consistent colony features, with minor variations in pigmentation, elevation, and margin. Biochemical assays showed that all isolates were Gram-negative and oxidase-positive, while 30% of isolates produced siderophores and 45% exhibited phosphate solubilization ability, indicating plant growth-promoting potential. Based on combined phenotypic traits, Based on phenotypic traits, one representative isolate AUPI-2 was selected for molecular identification. 16S rRNA gene sequencing and BLAST analysis confirmed its affiliation with the Pseudomonas fluorescens group (GenBank accession no. PX737072.1). The study provides baseline information on the diversity of Pseudomonas spp. associated with brinjal rhizosphere soils and highlights the need for further quantitative, antagonistic, and greenhouse-level studies to evaluate their functional role in disease suppression.