MdWRKY20<i>-MdPR1</i> module mediates resistance of apple to <i>Fusarium solani</i>

Apple replant disease (ARD) caused by the pathogen <i>Fusarium solani</i> is a destructive disease in apple planting areas worldwide, which leads to the decline of apple quality and yield. WRKY transcription factors are involved in the process of plants responding to various environmental stresses, but the function of WRKY TFs in ARD is unclear. In this study, the expression of <i>MdWRKY20</i> was significantly increased after infection of apple rootstock 'M9T337' with <i>F. solani</i>. Transgenic analysis showed that the resistance of apple callus and <i>Arabidopsis</i> to <i>F. solani</i> increased after overexpression of <i>MdWRKY20.</i> Ectopic expression of <i>MdWRKY20</i> also significantly enhanced antioxidant capacity in <i>Arabidopsis</i> under treatment with <i>F. solani.</i> Then, <i>MdWRKY20</i> was found to bind directly to the W-box II of the <i>MdPR1</i> promoter and significantly promoted its expression. In summary, <i>MdWRKY20</i> plays a positive role in regulating the resistance of apples to <i>F. solani</i>.