Survey of Viruses Infecting Basella alba in Hawaii

Malabar spinach plants (Basella alba, Basellaceae) with leaves exhibiting symptoms of mosaic, rugosity, and malformation were found in a community garden on Oahu, HI in 2018. Preliminary studies using enzyme-linked immunosorbent assay and reverse-transcription (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. 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.