Sphingomonas jeddahensis: A Newly Identified Causal Organism of Bacterial Blight Disease in Pomegranate from the Solapur District, India

Abstract: Pomegranate is a medicinally and economically important fruit crop cultivated in India. However, production of pomegranate has been severely reduced due to bacterial blight disease. According to recent studies, bacterial blight disease is recognized as one of the most devasting diseases affecting this crop, particularly in Tamil Nadu, Maharashtra, Haryana, and Punjab. The primary causal organism of blight disease is Xanthomonas axonopodis pv. punicae, which has been reported to reduce crop yields by up to 50% in India. To date, existing disease management strategies have proven ineffective in controlling this disease. In recent years, Pseudomonas spp. and other bacterial strains have also been implicated as causative agents of bacterial blight in pomegranates. In this study, research focused on the isolation of pathogens responsible for the bacterial blight disease in pomegranates. Samples, especially fruits, and leaves were used for the isolation from various zones of the Solapur district, Maharashtra. The ooze test was performed, and macerated samples of fruits and leaves were streaked onto YDCA medium. Well-isolated, yellow-pigmented bacterial colonies with acid hydrolysis activity were observed within 48 hrs. at 28°C. Further characterization and isolates were performed using cultural, morphological, biochemical, and molecular techniques, including 16S rRNA gene sequencing (up to 1200 bp). The isolates were identified as belonging to Sphingomonas jeddahensis. Pathogenicity was confirmed using an in vitro detached leaf assay, supporting the identification. According to the outcomes of this study, Sphingomonas jeddahensis is reported as a newly identified strain responsible for the cause of bacterial blight disease in pomegranate in the Solapur district, Maharashtra, in addition to Xanthomonas axonopodis pv. punicae and Pseudomonas spp. Keywords: Pomegranate, bacterial blight, Xanthomonas axonopodis pv. punicae, Pseudomonas spp., Sphingomonas jeddahensis, 16S rRNA gene sequencing.