• The embryonic cuticle integrity is critical for the embryo to separate from the neighboring endosperm. The sulfated TWISTED SEED1 (TWS1) peptide precursor generated in the embryo diffuses through gaps of the nascent cuticle to the surrounding endosperm, where it is cleaved by ABNORMAL LEAF SHAPE1 (ALE1) and becomes an active mature form. The active TWS1 is perceived by receptor-like protein kinases GASSHO1 (GSO1) and GSO2 in the embryonic epidermal cells to start the downstream signaling and guide the formation of an intact embryonic cuticle. However, the early signaling events after TWS1 is perceived by GSO1/2 are still unknown.
• Here, we report that serk1/2/3 embryos show cuticle defects similar to ale1, tws1, and gso1/2. Genetic and biochemical analyses were performed to dissect the signaling pathway mediated by SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASEs (SERKs) during cuticle development.
• SERKs function with GSO1/2 in a common pathway to monitor the integrity of the embryonic cuticle. SERKs interact with GSO1/2, which can be enhanced dramatically by TWS1. The phosphorylation levels of SERKs and GSO1/2 rely on each other and can respond to and be elevated by TWS1.
• Our results demonstrate that SERKs may function as coreceptors of GSO1/2 to transduce the TWS1 signal and ultimately regulate embryonic cuticle integrity.

中文翻译：

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SERKs 通过拟南芥 TWS1-GSO1/2 信号通路调节胚胎角质层完整性

• 胚胎角质层的完整性对于胚胎与邻近的胚乳分离至关重要。胚胎中产生的硫酸化 TWISTED SEED1 (TWS1) 肽前体通过新生角质层的间隙扩散到周围的胚乳，在那里它被 ABNORMAL LEAF SHAPE1 (ALE1) 切割并成为活跃的成熟形式。胚胎表皮细胞中的受体样蛋白激酶 GASSHO1 (GSO1) 和 GSO2 感知活性 TWS1 以启动下游信号传导并指导完整胚胎角质层的形成。然而，GSO1/2 感知到 TWS1 之后的早期信号事件仍然未知。
• 在这里，我们报告serk1/2/3胚胎表现出类似于ale1、tws1和gso1/2的角质层缺陷。进行遗传和生化分析以剖析在角质层发育过程中由体胚胎发生受体样激酶 (SERK) 介导的信号通路。
• SERK 与 GSO1/2 在共同的途径中发挥作用，以监测胚胎角质层的完整性。SERK 与 GSO1/2 交互，这可以通过 TWS1 显着增强。SERKs 和 GSO1/2 的磷酸化水平相互依赖，可以响应 TWS1 并被 TWS1 升高。
• 我们的研究结果表明，SERK 可以作为 GSO1/2 的辅助受体来转导 TWS1 信号并最终调节胚胎角质层的完整性。