A Novel Rubodvirus Associated with Progressive Leaf Whitening Disease in Bougainvillea: Genomic Insights and Phylogenetic Relationships

Bougainvillea sp. is an important ornamental and landscape plant in tropical and subtropical regions. In October 2024, progressive leaf whitening resembling viral infection was observed in Haikou, Hainan Province, China. To investigate the factors associated with progressive leaf whitening in bougainvillea (particularly viral pathogens), we performed virome analysis of two symptomatic leaf samples using total RNA sequencing with ribosomal RNA depletion on the Illumina NovaSeq 6000 platform. A novel tripartite negative-sense RNA virus was identified and tentatively named Bougainvillea progressive whitening virus (BgPWV), belonging to the genus Rubodvirus in the family Phenuiviridae. Its genome comprises RNA1–RNA3, each containing a single open reading frame flanked by untranslated regions, encoding the large protein (302 kDa), movement protein (43 kDa), and nucleocapsid protein (32 kDa), respectively. The 5′ and 3′ terminal sequences of each genomic RNA are highly conserved and complementary. Molecular screening of 54 bougainvillea plants showed that all 14 symptomatic plants tested positive for BgPWV, whereas all 40 asymptomatic samples tested were negative; three symptomatic plants were co-infected with Bougainvillea chlorotic vein banding virus. These results indicate a significant association between BgPWV and leaf whitening and expand the known host range and genetic diversity of rubodviruses, providing a foundation for future studies on bougainvillea viral diseases.