Barley Yellow Dwarf Virus-GAV-derived vsiRNAs Involved in the Production of Wheat Leaf Yellowing Symptoms by Targeting Chlorophyll Synthase

Abstract

Background: Wheat yellow dwarf virus disease was infected by barley yellow dwarf virus, caused leaf yellowing and dwarfing symptoms in wheat, posing a serious threat to China's food production. Infection of plant viruses can produce a large number of vsiRNAs, which can target host transcripts for symptoms development. However, few studies were conducted to explore the role of vsiRNAs in the interaction between BYDV-GAV and host wheat plants.Methods: In this study, small RNA sequencing was conducted to profile the vsiRNAs in BYDV-GAV infected wheat plants. The putative targets of vsiRNAs were predicted by bioinformatics software. RT-qPCR and VIGS were used to identify the function of selected target transcripts. To confirm the interaction between vsiRNA and the target, 5’RACE was performed to analyze the specific cleavage sites. Results: From the sequencing data, we obtained a total of 11,384 detected vsiRNAs. The length distribution of these vsiRNAs mostly was 21- and 22-nt along with A/U biased at the 5 ' -terminal. We also found the production region of vsiRNAs had no strand polarity. The vsiRNAs were predicted to target 23,719 wheat transcripts. GO and KEGG enrichment analysis revealed that these targets mostly involved in cell parts and catalytic activity and plant-pathogen interaction. The results of RT-qPCR indicted that most chloroplast-related genes showed down-regulation in BYDV-GAV infected wheat plants. Silencing of a chlorophyll synthase caused leaf yellowing that was similar to the symptom of BYDV-GAV inoculated wheat plants. A vsiRNA from an overlap region of BYDV-GAV MP and CP was found that could target the chlorophyll synthase for gene silencing. Then, 5’RACE validated that vsiRNA8856 could cleavage the chlorophyll synthase transcript in a sequence-specific manner.Conclusion: This is the first report demonstrating that BYDV-GAV-derived vsiRNAs can target wheat transcripts for symptom development, and this study provides new insights into the molecular mechanisms underlying leaf yellowing upon viral infection.

Barley GRIK1‐SnRK1 kinases subvert a viral virulence protein to upregulate antiviral RNAi and inhibit infection

“…This is consistent with the fact that antiviral RNA silencing mediated by vsiRNAs functions primarily at the early phase of viral infections (Pertermann et al , 2018). The length of BYDV vsiRNAs varied from 21 to 24 nts, with the major type having 22 nts (Fig 3C), which agrees well with the previous findings made in analyzing vsiRNAs present in the plants infected by turnip yellows virus, cotton leaf roll dwarf virus, or BYDV‐GAV (Silva et al , 2011; Shen et al , 2020; Clavel et al , 2021). The proportions of vsiRNAs with different sizes were similar in BYDV‐infected SnRK1‐YFP plants and WT controls (Fig 3C).…”