HomePlant DiseaseVol. 100, No. 6First Report of Bacterial Stem Rot of “Heirloom” Tomatoes Caused by Pectobacterium carotovorum subsp. brasiliensis in Florida PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Bacterial Stem Rot of “Heirloom” Tomatoes Caused by Pectobacterium carotovorum subsp. brasiliensis in FloridaE. Rosskopf and J. HongE. RosskopfSearch for more papers by this author and J. HongSearch for more papers by this authorAffiliationsAuthors and Affiliations E. Rosskopf J. Hong , USDA, ARS, Fort Pierce, FL 34982. Published Online:18 Mar 2016https://doi.org/10.1094/PDIS-09-15-0961-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In the spring of 2014, a field experiment was established to evaluate the growth of “heirloom” tomatoes in a vertical garden hydroponic system. During bloom, approximately 40% of the established ‘Black Prince’ plants were severely wilted with necrotic upper leaves. Stems of infected plants appeared water-soaked, and were hollow and necrotic internally. Diseased tissue was surface sterilized with 0.5% sodium hypochlorite solution, ground in sterile deionized water, and serial dilutions were plated onto 1/10th-strength tryptic soy agar. Several bacterial colony types were present on the culture medium, but a single colony type, transparent and colorless during the first 48 h, turning translucent blue with age, was dominant. Individual colonies were isolated and grown in tryptic soy broth overnight. Bacterial DNA was isolated using the MoBio Microbial DNA Isolation Kit. The isolate was putatively identified as Pectobacterium carotovorum, based on the symptoms observed. However, comparison of the tomato stem isolate with a previously isolated P. carotovorum subsp. carotovorum (Pcc) from tomato fruit led to amplifying the two isolates with Br1f and L1r, P. carotovorum subsp. brasiliensis (Pcb) subspecies-specific primers (Duarte et al. 2004). Only the stem isolate produced a 320-bp amplicon, characteristic of Pcb, the causal agent of soft rot and blackleg of potato in New Zealand (Panda et al. 2012). To confirm this identification, the 16S rRNA DNA sequence of the presumed Pcb isolate was amplified with the V2 and V3 primers (Schmalenberger et al. 2001). BLAST results indicated 99% sequence homology to the deposited sequence of Pcb NZEC1 GenBank Accession No. JQ771053.1. To confirm pathogenicity, a single isolate was used to inoculate Black Prince tomato plants. Five plants each were syringe-injected with either sterile water, 10 μl of 1 × 105 cfu/ml Pcc fruit rot isolate, or 10 μl of 1 × 105 cfu/ml Pcb and injection sites were wrapped with Parafilm to prevent contamination. Three of five Black Prince tomato plants inoculated with Pcb were wilted within 3 days of inoculation and the bacterium was reisolated, identity confirmed, and sequence deposited (KT626461). None of the control plants, nor the plants inoculated with the fruit rot pathogen developed wilt symptoms. To our knowledge, this is the first report of bacterial stem rot of tomatoes in Florida caused by P. carotovorum subsp. brasiliensis.