The interaction between the lemon ribosomal protein ClRPS9-2 and citrus yellow vein clearing virus coat protein affects viral infection and gene silencing suppressor activity.

Citrus yellow vein clearing virus (CYVCV) is an emerging virus that causes serious economic damage to the lemon industry worldwide. The coat protein (CP) of CYVCV is a strong RNA silencing suppressor and is associated with the severity of symptoms in citrus, yet the interaction between CP and host factors remains unknown. In this study, the 40S ribosomal subunit protein S9-2 (ClRPS9-2) was identified as a CP-binding partner using the yeast two-hybrid system from a lemon (cv. Eureka) cDNA library, and the interaction between CP and ClRPS9-2 was demonstrated by in vivo methods. The results suggest that the N-terminal 8-108 amino acid sequence of ClRPS9-2 is crucial for its interaction with CP and may be associated with the nuclear localization of ClRPS9-2. The accumulation and silencing suppressor activity of CP were reduced by transient expression of ClRPS9-2 in Nicotiana benthamiana. Reverse transcription-quantitative PCR analysis showed that the content of CYVCV in ClRPS9-2 transgenic Eureka lemon plants was approximately 50% of that in CYVCV-infected wild-type plants 1 month after inoculation, and mild yellowing and vein clearing symptoms were observed in the transgenic plants. These findings demonstrate that ClRPS9-2 plays a role in host defensive reactions, and the enhanced resistance of transgenic plants to CYVCV may be associated with the up-regulation of salicylic acid-related and R genes.

Development of transcription recombinase polymerase based isothermal amplification coupled with lateral flow immunochromatographic assay for visual detection of citrus tatter leaf virus.

The citrus tatter leaf virus (CTLV) is one of the most destructive citrus viral diseases worldwide. In this study, reverse transcription-recombinase polymerase amplification combined with a lateral flow dipstick (RT-RPA-LFD) assay for rapid visual detection of CTLV was established. The assay was performed at 35 â„ƒ in 27 min without specialised equipment. The RT-RPA-LFD assay showed high specificity to CTLV, and the sensitivity to CTLV was the same as that of quantitative RT-PCR at 3 × 103 copies/µL CTLV RNA transcripts. A total of 45 field tangor samples were tested using RT-RPA-LFD, RT-PCR, and RT-qPCR, and the results were consistent. The results demonstrated that the RT-RPA-LFD assay is a promising tool for rapid on-site CTLV detection.