Abstract：
Biosynthesis of the phytoalexins scopoletin and scopolin in Nicotiana species is regulated by upstream signals including jasmonate (JA), ethylene (ET) and NaWRKY3 in response to the necrotrophic fungus Alternaria alternata, which causes brown spot disease. However, how these signals are coordinated to regulate these phytoalexins remains unknown. By analyzing RNA sequencing data and RNA interference, we identified NaERF1B-like (NaERF1B-L) as a key player in Nicotiana attenuata during A. alternata infection by regulating the transcripts of Feruloyl-CoA 6\'-hydroxylase 1 (NaF6\'H1), encoding a key enzyme for scopoletin biosynthesis, and NaVS1-like (NaVS1-L), a putative biosynthetic gene of the phytoalexin solavetivone. We further demonstrated that the synergistic induction of these two genes by JA and ET signaling is mediated by NaERF1B-L. Additionally, we found that the two closely related proteins NaWRKY6 and NaWRKY3 physically interact to enhance NaERF1B-L expression by directly binding and activating the NaERF1B-L promoter. Collectively, our current results demonstrate that NaERF1B-L plays a positive role in resistance to A. alternata by modulating phytoalexins biosynthesis through the integration of JA/ET and NaWRKY6/3 signaling. Our findings reveal a fine-tuned transcriptional regulatory hierarchy mediated by NaERF1B-L for brown spot disease resistance in wild tobacco.
摘要：
烟草物种中植物抗毒素scopoetin和scopolin的生物合成受包括茉莉酸（JA）在内的上游信号调节，乙烯（ET）和NaWRKY3对坏死真菌Alternariaalternata的反应，导致褐斑病。然而,这些信号是如何协调调节这些植物抗毒素的，仍然是未知的。通过分析RNA测序数据和RNA干扰，我们通过调节阿魏酸-CoA6'-羟化酶1（NaF6'H1）的转录本，确定了NaERF1B样（NaERF1B-L）是烟草A感染期间的关键参与者。编码一种生物合成的关键酶，和NaVS1类(NaVS1-L)，植物抗毒素solavetivone推定的生物合成基因。我们进一步证明了JA和ET信号对这两个基因的协同诱导是由NaERF1B-L介导的。此外,我们发现两个密切相关的蛋白NaWRKY6和NaWRKY3通过直接结合和激活NaERF1B-L启动子而物理相互作用以增强NaERF1B-L表达。总的来说，我们目前的研究结果表明,NaERF1B-L通过整合JA/ET和NaWRKY6/3信号来调节植物抗毒素的生物合成,从而在抗交替a.我们的发现揭示了由NaERF1B-L介导的针对野生烟草的褐斑病抗性的微调转录调控体系。
