College of Life Sciences, Qingdao Agricultural University, Qingdao, China.
College of Horticulture, Qingdao Agricultural University, Qingdao, China.
J Exp Bot. 2022 Jun 2;73(11):3758-3773. doi: 10.1093/jxb/erac093.
Ring rot is a destructive apple disease caused by Botryosphaeria dothidea. The resistance mechanism of apple plants to B. dothidea remains unclear. Here, we show that APPLE VACUOLAR PROCESSING ENZYME 4 (MdVPE4) is involved in resistance to B. dothidea. MdVPE4 silencing reduced fruit disease resistance, whereas its overexpression improved resistance. Gene expression analysis revealed that MdVPE4 influenced the expression of fruit disease resistance-related genes, such as APPLE POLYGALACTURONASE 1 (MdPG1), APPLE POLYGALACTURONASE INHIBITOR PROTEIN 1 (MdPGIP1), APPLE ENDOCHITINASE 1 (MdCHI1), and APPLE THAUMATIN-LIKE PROTEIN 1 (MdTHA1). The expression of the four genes responding to B. dothidea infection decreased in MdVPE4-silenced fruits. Further analysis demonstrated that B. dothidea infection induced MdVPE4 expression and enzyme activation in apple fruits. Moreover, MdVPE4 activity was modulated by apple cysteine proteinase inhibitor 1 (MdCPI1), which also contributed to resistance towards B. dothidea, as revealed by gene overexpression and silencing analysis. MdCPI1 interacted with MdVPE4 and inhibited its activity. However, MdCPI1 expression was decreased by B. dothidea infection. Taken together, our findings indicate that the interaction between MdVPE4 and MdCPI1 plays an important role in modulating fruit disease resistance to B. dothidea.
轮纹病是一种由 Botryosphaeria dothidea 引起的破坏性苹果病害。苹果植株对 B. dothidea 的抗性机制尚不清楚。在这里，我们表明 APPLE VACUOLAR PROCESSING ENZYME 4 (MdVPE4) 参与了对 B. dothidea 的抗性。MdVPE4 的沉默降低了果实的抗病性，而其过表达则提高了抗性。基因表达分析显示，MdVPE4 影响了果实抗病相关基因的表达，如 APPLE POLYGALACTURONASE 1 (MdPG1)、APPLE POLYGALACTURONASE INHIBITOR PROTEIN 1 (MdPGIP1)、APPLE ENDOCHITINASE 1 (MdCHI1) 和 APPLE THAUMATIN-LIKE PROTEIN 1 (MdTHA1)。在 MdVPE4 沉默的果实中，这四个基因对 B. dothidea 感染的响应表达下降。进一步分析表明，B. dothidea 感染诱导了苹果果实中 MdVPE4 的表达和酶的激活。此外，苹果半胱氨酸蛋白酶抑制剂 1 (MdCPI1) 调节 MdVPE4 活性，该基因的过表达和沉默分析表明其也有助于对 B. dothidea 的抗性。MdCPI1 与 MdVPE4 相互作用并抑制其活性。然而，B. dothidea 感染导致 MdCPI1 表达降低。综上所述，我们的研究结果表明，MdVPE4 和 MdCPI1 之间的相互作用在调节果实对 B. dothidea 的抗性中起着重要作用。
