Characterization of Pectobacterium Carotovoratum Subsp. Carotovorum causing Bacterial Soft Rot Disease of Turnip in Pakistan

Abstract

This study aims to identify the Pectobacterium carotovorum subsp. carotovorum (Pcc) causing bacterial soft rot disease of turnip in Pakistan through conventional and molecular techniques. During the survey, four different bacterial isolates (VRSPCC01-04) were obtained from symptomatic turnip steckling (cv. purple top) at Vegetable Research Station Sahiwal, Punjab, Pakistan, and subjected for further analysis. All the isolates were characterized and identified based on morphological, biochemical, and molecular analysis (16S Ribosomal RNA). During morphological studies, the colony characters found deep cavities or pits formation in Crystal violet pectate medium (CVP), Creamy yellowish colony color was found on Yeast Extract Glucose calcium carbonate Medium (YGC), while creamy in color with the oval-shaped colony was observed on nutrient agar (NA) medium. In addition, the Pathogenicity test proved that all the tested isolates developed a typical water-soak symptom after 24 h and initiation of soft rot began the 48 h after inoculation on turnip roots. Results of biochemical tests showed that all isolates had a positive reaction for catalase, citrate, and an adverse reaction for Phosphatase and Indole test. The 16S rRNA sequences of isolates were 99-100% similar to the corresponding 16S rRNA sequence of the Pectobacterium carotovorum (PCC) reference isolates. Based on this, all identified bacterial isolates are first time reported as a causative agent of soft rot disease of turnip in Pakistan.