Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) seriously affects cassava yield. Nitrate reductase (NR) plays an important role in plant nitrogen metabolism in plants. However, the in vivo role of NR and the corresponding signalling pathway remain unclear in cassava. In this study, we isolated MeNR1/2 and revealed their novel upstream transcription factor MeRAV5. We also identified MeCatalase1 (MeCAT1) as the interacting protein of MeRAV5. In addition, we investigated the role of MeCatalase1 and MeRAV5‐MeNR1/2 module in cassava defence response. MeNRs positively regulates cassava disease resistance against CBB through modulation of nitric oxide (NO) and extensive transcriptional reprogramming especially in mitogen‐activated protein kinase (MAPK) signalling. Notably, MeRAV5 positively regulates cassava disease resistance through the coordination of NO and hydrogen peroxide (H₂O₂) level. On the one hand, MeRAV5 directly activates the transcripts of MeNRs and NO level by binding to CAACA motif in the promoters of MeNRs. On the other hand, MeRAV5 interacts with MeCAT1 to inhibit its activity, so as to negatively regulate endogenous H₂O₂ level. This study highlights the precise coordination of NR activity and CAT activity by MeRAV5 through directly activating MeNRs and interacting with MeCAT1 in plant immunity.

中文翻译：

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RAV5在激活硝酸还原酶和抑制过氧化氢酶活性以提高木薯抗病性方面的双重相互作用


木薯白叶枯病 (CBB) 由Xanthomonas axonopodis pv. 引起。木薯（ Xam ）严重影响木薯产量。硝酸还原酶（NR）在植物氮代谢中发挥着重要作用。然而，NR在木薯体内的作用和相应的信号通路仍不清楚。在这项研究中，我们分离了MeNR1/2并揭示了它们的新型上游转录因子MeRAV5。我们还鉴定出 MeCatalase1 (MeCAT1) 是 MeRAV5 的相互作用蛋白。此外，我们研究了 MeCatalase1 和 MeRAV5- MeNR1/2模块在木薯防御反应中的作用。 MeNRs通过调节一氧化氮 (NO) 和广泛的转录重编程，特别是在丝裂原激活蛋白激酶 (MAPK) 信号传导中，积极调节木薯对 CBB 的抗病性。值得注意的是，MeRAV5 通过协调 NO 和过氧化氢 (H ₂ O ₂ ) 水平积极调节木薯抗病性。一方面，MeRAV5通过与MeNRs启动子中的CAACA基序结合，直接激活MeNRs和NO水平的转录本。另一方面，MeRAV5与MeCAT1相互作用抑制其活性，从而负向调节内源性H ₂ O ₂水平。这项研究强调了MeRAV5通过直接激活MeNR并与植物免疫中的MeCAT1相互作用来精确协调NR活性和CAT活性。