Fig. 7: BRCA1, HOP2 and CYCB1 regulate the antiviral defense in an RAD51-dependent manner. | Nature Communications

Fig. 7: BRCA1, HOP2 and CYCB1 regulate the antiviral defense in an RAD51-dependent manner.

From: H3.1K27me1 loss confers Arabidopsis resistance to Geminivirus by sequestering DNA repair proteins onto host genome

Fig. 7

a Y2H assays validated the interactions of RAD51 with CYCB1 and BRCA1. b Co-IP assay validated the interactions of RAD51 with CYCB1, BRCA1, and HOP2 in planta. FM-Rep and Coomassie blue staining of blots serve as negative and loading controls, respectively. The experiments were repeated twice with similar results. c ChIP-qPCR assay shows that BRCA1, HOP2 and CYCB1 are required for recruitment of RAD51 over rDNA and PCGs in atxr5 atxr6. d ChIP-qPCR assay shows that BRCA1, HOP2, and CYCB1 are required for reduced binding of RAD51 over the viral genome in atxr5 atxr6. e Representative pictures of the virus-inoculated plants in indicated backgrounds. Photographs were taken on at 15 dpi. Scale bars, 1 cm. f Percentages of symptomatic plants of virus-inoculated plants in indicated backgrounds. g, q-PCR assays show the amount of viral DNA A in CaLCuV-inoculated plants indicated at 16 dpi. Normalization of viral DNA was conducted as Fig. 2g. In (c), (d), (f), and (g), each dot in the bar plot represents one replicate, experiments were performed with 32 plants/replicate. Data are presented as mean ± SD (n = 3 biological replicates). h A proposed model for Geminivirus competition with host genome for HRR to facilitate viral amplification. In the WT plants with a stable genome the virus inoculation suppresses the transcription of defense-related genes to evict RAD51 and RPA1A from host genome, and then viral-encoded Rep protein hijacks RAD51 and RPA1A for efficient viral replication. However, in atxr5 atxr6, unstable host DNA retains large amount of DNA repairing factors and promotes the transcription of defense-related genes. Consequently, unstable host heterochromatic elements coordinate with the upregulated defense-related genes to retain a large amount of DNA repairing machinery to prevent its rerouting to viral genome, leading to low-efficiency virus amplification. Figure 7h was created with BioRender.com. Statistics in Figs. 7c, d, f, and g were performed with unpaired two-tailed student t-test, *, **, *** and ****, P < 0.05, 0.01, 0.001, and 0.0001, respectively. Source data are provided in the Source Data File.

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