First report of Xylella fastidiosa subsp. multiplex associated with bacterial leaf scorch on American elderberry (Sambucus canadensis L.) in Oklahoma

Authors: Chen, Jianchi; JIBRIN, MUSTAFA - Oklahoma State University; OLSON, JENNIFER - Oklahoma State University; Andrade, Yadira

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2025
Publication Date: 10/24/2025
Citation: Chen, J., Jibrin, M.O., Olson, J., Andrade, Y. 2025. First report of Xylella fastidiosa subsp. multiplex associated with bacterial leaf scorch on American elderberry (Sambucus canadensis L.) in Oklahoma. Plant Disease. 109(11). https://doi.org/10.1094/PDIS-03-25-0590-PDN.
DOI: https://doi.org/10.1094/PDIS-03-25-0590-PDN

Interpretive Summary: Elderberry is an important medicinal plant. In Oklahoma, elderberries are usually harvested from wild growing plants, but recent efforts have seen an upsurge in acreage in elderberry production. In 2024, leaf scorch symptoms were found on elderberry plants growing in the Oklahoma State University Native Plant Corridor collections in Stillwater campus. Ten leaf samples were collected and tested positive for a bacterial pathogen, Xylella fastidiosa, by a molecular technique called PCR and a next generation sequencing method. The bacterial pathogen is known to cause many plant diseases such as pecan leaf scorch in the southern U.S. This finding is important in understanding and management of Xylella disease in elderberry production and potential spread to other horticultural plants in Oklahoma.

Technical Abstract: Elderberry (Sambucus canadensis L.) is an important medicinal plant. In Oklahoma, elderberries are usually harvested from wild growing plants, but recent efforts have seen an upsurge in acreage in elderberry production. In 2024, leaf scorch symptoms were found on elderberry plants growing in the Oklahoma State University Native Plant Corridor collections in Stillwater campus. Ten leaf samples were collected and tested using SYBR-green q-PCR. Xylella fastidiosa subsp. multiplex (Xfm) was detected in all samples. A representative sample STW-2 (Ct = 14.63 for a Xfm-specific primer set Dixon454fa/Dixon1261rg) was selected for next generation sequencing using the Illumina NovaSeqX Plus platform. A total of 90, 038, 597 paired reads (150 bp per read) was generated. High read mapping percentage using Bowtie2 further confirmed the Xfm identity of the elderberry sample. BLAST search using the top 5 and bottom 5 reads from the mapped-read data set against the NCBI core-nr database showed that all the top hits were Xfm (query coverage = 100%, Percentage Identity = 100%). All three analyses (PCR, read mapping, and BLAST search) indicated Xfm as the causal organism of bacterial leaf scorch of elderberry. This finding is therefore important in understanding epidemiology and management of Xfm in the increasingly important elderberry production landscape and potential spread to other horticultural plants in Oklahoma.