Survey of viruses infecting Basella alba in Hawaii

Authors: WANG, XUPENG - University Of Hawaii; LARREA-SARMIENTO, ANDREW - University Of Hawaii; OLMEDO-VELARDE, ALEJANDRO - University Of Hawaii; AL RWAHNIH, MAHER - University Of California, Davis; BORTH, WAYNE - University Of Hawaii; Suzuki, Jon; Wall, Marisa; MELZER, MICHAEL - University Of Hawaii; HU, JOHN - University Of Hawaii

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2022
Publication Date: 9/27/2022
Citation: Wang, X., Larrea-Sarmiento, A., Olmedo-Velarde, A., Al Rwahnih, M., Borth, W., Suzuki, J.Y., Wall, M.M., Melzer, M., Hu, J. 2022. Survey of viruses infecting Basella alba in Hawaii. Plant Disease. 107(4):1022-1026. https://doi.org/10.1094/PDIS-02-22-0449-SR.
DOI: https://doi.org/10.1094/PDIS-02-22-0449-SR

Interpretive Summary: Malabar spinach leaves with virus infection-like symptoms were found in a community garden on the island of Oahu, Hawaii in 2018. Using antibody- as well as polymerase chain reaction (PCR)-based detection methods, researchers identified the plant RNA virus, basella rugose mosaic virus (BaRMV) in symptomatic plants. A more comprehensive analysis of Malabar spinach with virus infection-like symptoms from three different locations using modern sequencing methods identified not only BaRMV, but additional RNA viruses including chilli veinal mottle virus (ChiVMV), alternanthera mosaic virus (AltMV), basella alba endornavirus (BaEV), broad bean wilt virus 2 (BBWV2), and a so-called viroid, Iresine viroid 1 (IrVd-1), an RNA-based, virus-like element. Additional malabar spinach samples from the community gardens were examined to determine the incidence, distribution, and diversity of these viruses and the viroid. Of 63 samples, 21 were positive for BaRMV, 57 were positive for ChiVMV, 21 were positive for AltMV, 19 were positive for BaEV, and 14 were positive for BBWV2.

Technical Abstract: Malabar spinach (Basella alba, Basellaceae) with leaves exhibiting symptoms of mosaic, rugosity, and malformation were found in a community garden on Oahu, Hawaii, in 2018. Preliminary studies using ELISA and RT-PCR identified basella rugose mosaic virus (BaRMV) in symptomatic plants. However, nucleotide sequence analysis of RT-PCR amplicons indicated that additional potyviruses were also present in the symptomatic Malabar spinach. High-throughput sequencing (HTS) analysis was conducted on ribosomal RNA-depleted composite RNA samples of potyvirus-positive plants from three locations. Assembled contigs shared sequences similar to BaRMV, chilli veinal mottle virus (ChiVMV), alternanthera mosaic virus (AltMV), basella alba endornavirus (BaEV), broad bean wilt virus 2 (BBWV2), and Iresine viroid 1 (IrVd-1). Virus- and viroid-specific primers were designed based on HTS sequencing results and used in RT-PCR and Sanger sequencing to confirm the presence of these viruses and the viroid. We tested 63 additional samples from six community gardens for a survey of viruses in Malabar spinach and found that 21 of them were positive for BaRMV, 57 for ChiVMV, 21 for AltMV, 19 for BaEV, and 14 for BBWV2. This is the first characterization of the virome from B. alba.