First report of serratia marcescens causing cucurbit yellow vine disease in New York

Authors: RODRIGUEZ-HERRERA, KENSY - Cornell University; MA, XING - Cornell University; Swingle, Bryan; PETHYBRIDGE, SARAH - Cornell University; GONZALEZ-GIRON, JUAN - Cornell University; HERRMANN, TAYLERE - Cornell University; DAMANN, KELLIE - Cornell University; SMART, CHRISTINE - Cornell University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2023
Publication Date: 7/24/2023
Citation: Rodriguez-Herrera, K.D., Ma, X., Swingle, B.M., Pethybridge, S.J., Gonzalez-Giron, J.L., Herrmann, T.Q., Damann, K., Smart, C.D. 2023. First report of serratia marcescens causing cucurbit yellow vine disease in New York. Plant Disease. https://doi.org/10.1094/PDIS-06-23-1051-PDN.
DOI: https://doi.org/10.1094/PDIS-06-23-1051-PDN

Interpretive Summary: Cucurbits are an important crop in New York with a value of $92.3 million in 2021. In August 2021 and 2022, muskmelon, acorn squash, and delicata squash at Cornell AgriTech in Geneva, NY exhibited symptoms of cucurbit yellow vine disease (CYVD), including leaf yellowing, wilting, and phloem discoloration. The causal agent was identified by isolating bacteria from symptomatic plant stems and using PCR and DNA sequencing to identify S. marcescens in the diseased plants. To confirm that these bacteria were responsible for the disease, healthy delicata squash plants were inoculated with the S. marcescens isolates. This resulted in the development of CYVD-like symptoms 28 days later. Bacterial isolations from the infected plants were confirmed to be identical to the original isolates through sequencing. This is the first known report of CYVD and phytopathogenic S. marcescens in New York, and more research is needed to determine its biology and incidence in the region. The severity of CYVD can cause up to 100% crop loss.

Technical Abstract: This study describes the emergence of cucurbit yellow vine disease (CYVD) in New York, a significant producer of cucurbits with a value of $92.3 million in 2021. In August 2021, muskmelon plants at Cornell AgriTech showed symptoms of yellowing, wilting, and phloem discoloration. These symptoms were also observed in 2022 on muskmelon, acorn squash, and delicata squash plants. The symptoms were consistent with those caused by CYVD, a disease previously reported in other regions of the United States, caused by Serratia marcescens. To identify the causal agent, stems from symptomatic plants were surface sterilized, macerated, and streaked on King's B medium. After incubation, white round bacterial colonies grew, which were identified as S. marcescens by PCR using specific primers for the 16S rDNA region and 79F/R primers specific for the S. marcescens that causes CYVD. Sanger sequencing of the PCR products confirmed the bacteria isolated from the infected plants were S. marcescens. To confirm the pathogenicity of the isolates, delicata squash plants were inoculated with two of the S. marcescens isolates, resulting in the development of CYVD-like symptoms after 28 days. Isolations were made from the stems of symptomatic plants, and PCR using the same primers as above amplified products only from the symptomatic plants inoculated with the S. marcescens isolates. Sequencing confirmed that the reisolated S. marcescens were identical to those used to inoculate the plants. This study highlights the importance of studying S. marcescens, which can cause significant losses in cucurbit crops, with some reports suggesting up to 100% crop loss. This report is the first to describe CYVD and phytopathogenic S. marcescens in New York.