• WOX family transcription factors regulate multiple developmental programs. The intermediate clade transcriptional activator WOX9 functions together with the modern clade transcriptional repressor WOX genes in embryogenesis and meristems maintenance, but the mechanism of this interaction is unclear.
• STF and LAM1 are WOX1 orthologs required for leaf blade outgrowth in Medicago truncatula and Nicotiana sylvestris, respectively. Using biochemical methods and genome editing technology, here we show that WOX9 is an abaxial factor and functions antagonistically to STF and LAM1 to regulate leaf blade development.
• While NsWOX9 ectopic expression enhances the lam1 mutant phenotype, and antisense expression partially rescues the lam1 mutant, both overexpression and knockout of NsWOX9 in N. sylvestris resulted in a range of severe leaf blade distortions, indicating important role in blade development. Our results indicate that direct repression of WOX9 by WUS clade repressor STF/LAM1 is required for correct blade architecture and patterning in M. truncatula and N. sylvestris.
• These findings suggest that controlling transcriptional activation and repression mechanisms by direct interaction of activator and repressor WOX genes may be required for cell proliferation and differentiation homeostasis, and could be an evolutionarily conserved mechanism for the development of complex and diverse morphology in flowering plants.

中文翻译：

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WOX9的功能与STF和LAM1拮抗，可调节截叶苜蓿和烟草中的叶片膨胀。

• WOX家族转录因子调节多种发育程序。中间进化枝转录激活因子WOX9与现代进化枝转录抑制因子WOX基因一起在胚胎发生和分生组织维持中起作用，但这种相互作用的机制尚不清楚。
• STF和LAM1分别是t藜苜蓿和欧洲烟草对叶片长出所需的WOX1直系同源物。使用生化方法和基因组编辑技术，在这里我们显示WOX9是一种背轴因子，对STF和LAM1具有拮抗作用，以调节叶片发育。
• 虽然NsWOX9异位表达增强了lam1突变体的表型，而反义表达部分地挽救了lam1突变体，但NsWOX9在樟子松中的过度表达和敲除均导致一系列严重的叶片畸变，表明在叶片发育中的重要作用。我们的研究结果表明，直接压制WOX9由WUS分支阻遏STF LAM1需要/正确刀片架构和模式在蒺藜苜蓿和N.樟子松。
• 这些发现表明，通过细胞激活和阻遏物WOX基因的直接相互作用来控制转录激活和阻抑机制可能是细胞增殖和分化稳态的必要条件，并且可能是进化上保守的机制，可以使开花植物形成复杂多样的形态。