Abstract
Viral pathogens are a major threat to stable crop production. Using a backcross strategy, we find that integrating a dominant brown planthopper (BPH) resistance gene Bph3 into a high-yield and BPH-susceptible indica rice variety significantly enhances BPH resistance. However, when Bph3-carrying backcross lines are infested with BPH, these BPH-resistant lines exhibit sterile characteristics, displaying panicle enclosure and failure of seed production at their mature stage. As we suspected, BPH-mediated viral infections could cause the observed sterile symptoms, and we characterized rice-infecting viruses using deep metatranscriptomic sequencing. Our analyses revealed eight novel virus species and five known viruses, including a highly divergent virus clustered within a currently unclassified family. Additionally, we characterized rice plant antiviral responses using small RNA sequencing. The results revealed abundant virus-derived small interfering RNAs in sterile rice plants, providing evidence for Dicer-like and Argonaute-mediated immune responses in rice plants. Together, our results provide insights into the diversity of viruses in rice plants, and our findings suggest that multiple virus infections occur in rice plants.
Highlights
Accepted: 6 December 2021Rice (Oryza sativa) is one of the most important global cereal crops and feeds roughly half of the world’s population
To develop an indica rice variety resistant to brown planthopper (BPH), Ms55 was used as a recurrent parent to backcross with the TZ21 line that harbors a BPH resistance gene, Bph3
These crosses resulted in backcrossed first generation (BC1 F) population that may be resistant to BPH (Figure 1a and Figure S1)
Summary
Accepted: 6 December 2021Rice (Oryza sativa) is one of the most important global cereal crops and feeds roughly half of the world’s population. The brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive pest of rice and a substantial threat to rice production, causing billions of dollars in crop losses annually [5,6]. Validation of BPH resistance in the backcrossed first generation (BC1 F) was completed by selecting and cultivating Rby and Rby carrying Bph3 Both of these rice lines grow as healthy rice plants following BPH infestation, but become sterile at a mature stage. We speculated that the observed sterile symptoms in BC1 F are due to BPH-transmitted viruses and subsequent viral infections.
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