The Complete Genome Sequence, Molecular Detection, and Anatomical Analysis of Hibiscus Chlorotic Ringspot Virus Infecting Hibiscus rosa-sinensis in Peninsular Malaysia

Hibiscus rosa-sinensis is the national flower of Malaysia and is widely cultivated as landscape planting across the nation. In 1995, Hibiscus chlorotic ringspot virus (HCRSV) was reported for the first time in Malaysia. Until today, there have been no follow-up studies on the viral infection in the plant, yet the virus symptom of chlorotic spots has been observed throughout the Hibiscus population. Therefore, this study aimed to report the complete genome sequence of the HCRSV, validate a molecular detection tool for its diagnosis, and measure the impact of the virus symptom and infection in H. rosa-sinensis. This study reported the complete genome of the HCRSV through RNA sequencing. The phylogenetic analysis of the HCRSV isolated from different geographical sources and several other related viruses was performed to confirm its identity and classification. Additionally, primers based on the genome sequence were designed and used for RT-PCR to detect the presence of the virus in symptomatic leaves, further confirming the HCRSV identity and presence. Meanwhile, the impact of the virus was measured by examining the anatomical and morphological changes in the leaf structure of symptomatic samples. Light microscopy and scanning electron microscopy were used to examine potential adaptations and comparisons between the leaf structures of healthy and infected samples, especially in the leaf lamina, petiole, and midrib cells. The results confirmed the complete genome sequence of the HCRSV, its molecular detection strategy, and the impact of the viral infection on Hibiscus leaves in Peninsular Malaysia. This study is beneficial for the management strategy of the virus and for protecting an important plant in the nation.