First report of Hibiscus latent Singapore virus and Hibiscus latent Fort Pierce virus infecting Lantana camara in China

Hibiscus latent Singapore virus (HLSV) and Hibiscus latent Fort Pierce virus (HLFPV) both belong to the genus Tobamovirus in the family Virgaviridae. The genomes of both HLSV and HLFPV consist of a linear positive sense single-stranded RNA of about 6.3 kb. HLSV is the causal agent of hibiscus leaf crinkle disease. Infections of HLSV in hibiscus (Hibiscus rosa-sinensis) have so far only been reported in Singapore, Japan and Malaysia (Srinivasan et al., 2002; Yoshida et al., 2018; Yusop et al., 2021). In 2017, leaf curling and chlorosis symptoms of lantana (Lantana camara) plants were found in Chenshan Botanical Garden, Shanghai, China. To detect potential virus(es) in these lantana samples, leaves from one lantana plant were collected and total RNA was extracted with RNAiso Plus (TaKaRa). A cDNA library was prepared by TruSeq RNA Sample Prep Kit (Illumina) after removing ribosomal RNA by Ribo-ZeroTM rRNA Removal Kit (Epicentre). The paired-end sequencing was then performed on an Illumina NovaSeq 6000. A total of 61,085,018 high quality reads were obtained and de novo assembly by StringTie revealed 124,516 contigs (greater than 50 bp, N50=719 bp) with an average length of 537 bp. BLASTx analyses in the National Center for Biotechnology Information (NCBI) database showed that 1 long contig of 6,305 bp, assembled of 1794 clean reads, shared significant nucleotide similarities with the genomic sequence of HLSV, and 1 contig of 6,271 bp, assembled of 3174 clean reads, shared significant similarities with the genomic sequence of HLFPV, yielding an average coverage of the whole genome at 42.65 and 75.83 per million reads, respectively. To obtain the complete genome of the viral RNA in this lantana sample, eleven overlapping regions covering the entire HLSV viral genome, and nine overlapping regions covering the entire HLFPV viral genome were amplified by reverse transcription-PCR (RT-PCR) and sequenced. In addition, the exact 5' and 3' ends of the genomic RNA of each virus were determined by rapid amplification of the cDNA ends (RACE) (Wang et al. 2020). The complete genome of the identified HLSV, deposited in GenBank: MZ020960, is 6,486 nt in length and shows 98.4% nucleotide sequence identity with HLSV Singapore isolate (GenBank: AF395898). Similar to other HLSV isolates, this virus isolate possesses an internal poly(A) tract of 87 nucleotides, which is crucial to virus replication (Niu et al., 2015). The complete genome of the Lantana HLFPV isolate is 6,463 nt (GenBank MZ020961) including a 73 nt internal poly(A) tract, and has 98.4% nt identity to HLFPV-Japan (AB917427). In two other lantana plants from the same site, the presence of HLSV and HLFPV was confirmed by RT-PCR using the primer pairs (5'-GCATCTGCATAACACGGTTG-3'/5'-ACGTTGTAGTAGACGTTGTTGTAG-3' and 5'-GGACCTTGCTAATCCGCTAAAGTTG-3'/5'-GGTCCATGTCCATCCAGATGCAATC-3'). In addition to the HLSV and HLFPV genomes, BLASTx analysis of three contigs of 3,006 bp, 2,845 bp and 2,200 bp, assembled of 1328, 352 and 2280 clean reads respectively, showed high identity to RNAs 1 (MG182148), 2 (DQ412731) and 3 (KY794710) of cucumber mosaic virus. To the best of our knowledge, this is the first report of L. camara as a new natural host of HLSV and HLFPV, and first identification of a mixed infection of HLSV and HLFPV.