Rice<scp>O</scp>s<i><scp>PAD</scp>4</i>functions differently from<scp>A</scp>rabidopsis<scp>A</scp>t<i><scp>PAD</scp>4</i>in host‐pathogen interactions

<jats:title>Summary</jats:title><jats:p>The extensively studied<jats:styled-content style="fixed-case">A</jats:styled-content>rabidopsis phytoalexin deficient 4 (<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>) gene plays an important role in<jats:styled-content style="fixed-case">A</jats:styled-content>rabidopsis disease resistance; however, the function of its sequence ortholog in rice is unknown. Here, we show that rice<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>appears not to be the functional ortholog of<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>in host‐pathogen interactions, and that the Os<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>encodes a plasma membrane protein but that<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>encodes a cytoplasmic and nuclear protein. Suppression of Os<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>by<jats:styled-content style="fixed-case">RNA</jats:styled-content>interference (<jats:styled-content style="fixed-case">RNA</jats:styled-content>i) increased rice susceptibility to the biotrophic pathogen<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>anthomonas oryzae</jats:italic>pv.<jats:italic>oryzae</jats:italic>(<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>oo</jats:italic>), which causes bacteria blight disease in local tissue.<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>‐<jats:styled-content style="fixed-case">RNA</jats:styled-content>i plants also show compromised wound‐induced systemic resistance to<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>oo</jats:italic>. The increased susceptibility to<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>oo</jats:italic>was associated with reduced accumulation of jasmonic acid (<jats:styled-content style="fixed-case">JA</jats:styled-content>) and phytoalexin momilactone<jats:styled-content style="fixed-case">A</jats:styled-content>(<jats:styled-content style="fixed-case">MOA</jats:styled-content>). Exogenous application of<jats:styled-content style="fixed-case">JA</jats:styled-content>complemented the phenotype of<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>‐<jats:styled-content style="fixed-case">RNA</jats:styled-content>i plants in response to<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>oo</jats:italic>. The following results suggest that<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>functions differently than<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>in response to pathogen infection. First,<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>plays an important role in wound‐induced systemic resistance, whereas<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>mediates systemic acquired resistance. Second,<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>‐involved defense signaling against<jats:italic><jats:styled-content style="fixed-case">X</jats:styled-content>oo</jats:italic>is<jats:styled-content style="fixed-case">JA</jats:styled-content>‐dependent, but<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>‐involved defense signaling against biotrophic pathogens is salicylic acid‐dependent. Finally,<jats:styled-content style="fixed-case">O</jats:styled-content>s<jats:italic><jats:styled-content style="fixed-case">PAD</jats:styled-content>4</jats:italic>is required for the accumulation of terpenoid‐type phytoalexin<jats:styled-content style="fixed-case">MOA</jats:styled-content>in rice‐bacterium interactions, but<jats:styled-content style="fixed-case">A</jats:styled-content>t<jats:italic><jats:styled-c ...