Figure 9.

Model of the H2Bub1 mechanism used to regulate defense responses to Vd-toxins in Arabidopsis. In this model, HUB-mediated H2Bub1 regulates the expression of the NADPH oxidase RbohD and WRKY33 by enhancing the enrichment of H3K4me3 in response to Vd-toxins. H2Bub1 also affects posttranscriptional MAPK signaling. H2Bub1 is required for the activation of MPK3 and MPK6. Phosphorylation of WRKY33 by MPK3 and MPK6 regulates the expression of RbohD. Moreover, MPK3 and MPK6 associate with PTPs, which negatively regulate H₂O₂ production. The PTP-MPK3/6-WRKY pathway regulates H₂O₂ signals in the responses against Vd-toxins in Arabidopsis.