With 1 AP2 domain and 1 B3 domain, 7 MeRAVs in apetala2/ethylene response factor (AP2/ERF) gene family have been identified in cassava. However, the in vivo roles of these remain unknown. Gene expression assays showed that the transcripts of MeRAVs were commonly regulated after Xanthomonas axonopodis pv manihotis (Xam) and MeRAVs were specifically located in plant cell nuclei. Through virus‐induced gene silencing (VIGS) in cassava, we found that MeRAV1 and MeRAV2 are essential for plant disease resistance against cassava bacterial blight, as shown by the bacterial propagation of Xam in plant leaves. Through VIGS in cassava leaves and overexpression in cassava leave protoplasts, we found that MeRAV1 and MeRAV2 positively regulated melatonin biosynthesis genes and the endogenous melatonin level. Further investigation showed that MeRAV1 and MeRAV2 are direct transcriptional activators of 3 melatonin biosynthesis genes in cassava, as evidenced by chromatin immunoprecipitation‐PCR in cassava leaf protoplasts and electrophoretic mobility shift assay. Moreover, cassava melatonin biosynthesis genes also positively regulated plant disease resistance. Taken together, this study identified MeRAV1 and MeRAV2 as common and upstream transcription factors of melatonin synthesis genes in cassava and revealed a model of MeRAV1 and MeRAV2‐melatonin biosynthesis genes‐melatonin level in plant disease resistance against cassava bacterial blight.

中文翻译：

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RAV转录因子通过褪黑素生物合成基因的活化对于木薯细菌性枯萎病的抗病性至关重要

在木薯中已鉴定出具有1个AP2域和1个B3域的Apetala2 /乙烯反应因子（AP2 / ERF）基因家族中的7个MeRAV。然而，这些的体内作用仍然未知。基因表达分析表明，转录MeRAVs后通常调节黄单胞axonopodis PV manihotis（XAM）和MeRAVs是专门设在植物细胞核。通过木薯中病毒诱导的基因沉默（VIGS），我们发现MeRAV1和MeRAV2对于植物抗木薯白叶枯病的抗病性至关重要，如Xam细菌繁殖所示在植物的叶子上。通过木薯叶中的VIGS和木薯叶原生质体中的过表达，我们发现MeRAV1和MeRAV2积极调节褪黑激素的生物合成基因和内源性褪黑激素水平。进一步的研究表明，MeRAV1和MeRAV2是木薯中3种褪黑激素生物合成基因的直接转录激活因子，木薯叶原生质体中的染色质免疫沉淀PCR和电​​泳迁移率变动分析证明了这一点。此外，木薯褪黑激素生物合成基因也正调节植物抗病性。两者合计，这项研究确定了MeRAV1和MeRAV2是木薯中褪黑激素合成基因的共同和上游转录因子，并揭示了一个模型。MeRAV1和MeRAV2-褪黑激素生物合成基因-褪黑激素水平对植物对木薯细菌性疫病的抗性。