The transcription factor Woolly (Wo) and its downstream gene CycB2 have been shown to regulate trichome development in tomato (Solanum lycopersicum). It has been demonstrated that only the gain-of-function allele of Slwo (SlWoV, the Slwo woolly motif mutant allele) can increase the trichome density; however, it remains unclear why the two alleles function differently in trichome development. In this study, we used Nicotiana benthamiana as a model and cloned the homologues of Slwo and SlCycB2 (named Nbwo and NbCycB2). We also constructed a Nbwo gain-of-function allele with the same mutation site as SlWoV (named NbWoV). We found that both Nbwo and NbWoV directly regulate NbCycB2 and their own expression by binding to the promoter of NbCycB2 and their own genomic sequences. As form of a feedback regulation, NbCycB2 negatively regulates trichome formation by repressing Nbwo activity at the protein level. We also found that mutations in the Nbwo woolly motif can prevent repression of NbWoV by NbCycB2, which results in a significant increase in the amount of active Nbwo proteins and in increases in trichome density and the number of branches. Our results reveal a novel reciprocal regulation mechanism between NbCycB2 and Nbwo during trichome formation in N. benthamiana.

中文翻译：

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NbCycB2 通过烟草毛状体发育中的负反馈回路抑制 Nbwo 活性。


转录因子 Woolly (Wo) 及其下游基因 CycB2 已被证明可以调节番茄 (Solanum lycopersicum) 的毛状体发育。已经证明，只有Slwo的功能获得性等位基因（SlWoV，Slwo羊毛基序突变体等位基因）才能增加毛状体密度；然而，目前尚不清楚为什么这两个等位基因在毛状体发育中的功能不同。在本研究中，我们以本塞姆氏烟草为模型，克隆了Slwo和SlCycB2的同源物（命名为Nbwo和NbCycB2）。我们还构建了一个与 SlWoV 具有相同突变位点的 Nbwo 功能获得等位基因（命名为 NbWoV）。我们发现Nbwo和NbWoV都通过与NbCycB2的启动子及其自身基因组序列结合来直接调节NbCycB2及其自身的表达。作为反馈调节的形式，NbCycB2 通过在蛋白质水平抑制 Nbwo 活性来负向调节毛状体的形成。我们还发现，Nbwo 羊毛基序的突变可以阻止 NbCycB2 对 NbWoV 的抑制，从而导致活性 Nbwo 蛋白数量显着增加，毛状体密度和分支数量增加。我们的结果揭示了本塞姆氏烟草毛状体形成过程中 NbCycB2 和 Nbwo 之间的一种新的相互调节机制。