First Report of Pseudomonas cichorii Causing Leaf Spot of Stevia Detected in Florida

During a routine nursery inspection in Hernando County, Florida in July 2011, leaf spot symptoms were observed on the popular sugar substitute stevia (Stevia rebaudiana). Spots were roughly circular to irregular in shape, variable in size, and dark brown with a yellow halo. White to cream-colored, circular, convex, gram-negative bacterial colonies were isolated on nutrient agar and identified as Pseudomonas cichorii based on the LOPAT scheme (2). DNA from four individual colonies inoculated in nutrient broth was extracted using DNeasy columns (Qiagen Inc., Valencia, CA). The PCR-amplified product from four different genes, 16S rRNA (1.5 Kbp), gyrB (0.9 Kbp), rpoB (1.2 Kbp), and rpoD (0.7 Kbp), was sequenced (GenBank Accession Nos. JQ994483, JQ994484, JQ994485, and JQ994486). Nucleotide and translated amino acid sequences for each gene were compared to the nucleotide and protein databases, respectively. The best matches were always with P. cichorii with nucleotide identities ranging from 98 to 99% and amin...