Xi Xiaoyuan, Hu Zhengdao, Nie Xuerui, Meng Mingming, Xu Hao, Li Jing
College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
College of Tropical Crops, Hainan University, Haikou, China.
Front Plant Sci. 2021 Apr 9;12:640346. doi: 10.3389/fpls.2021.640346. eCollection 2021.
The product of double fertilization produces seed, which contains three components: triploid endosperm, diploid embryo, and maternal seed coat. Amongst them, the endosperm plays a crucial role in coordinating seed growth. Mitogen-activated protein kinase (MAPK) cascades are conserved in eukaryotes and involved in signal transduction of plant development. MPK3, MPK6, and MPK10 form a small group of MPKs family in . MPK3 and MPK6 are extensively studied and were found to be involved in diverse processes including plant reproduction. However, less is known about the function of MPK10. Here, we found , a member of HAIKU (IKU) pathway engaging in endosperm development, and is high-specifically expressed in the early developmental endosperm but with opposite gradients. We further proved that MPK10 and WRKY10 cross-inhibit the expression of each other. The inhibition effect of MPK10 on gene expression of and the downstream targets is supported by the fact that MPK10 interacts with WRKY10 and suppresses the transcriptional activity of WRKY10. Constantly, mutants produce big seeds while positively regulate seed growth. Altogether, our data provides a model of WRKY10 and MPK10 regulating endosperm development with a unique cross inhibitory mechanism.
双受精的产物形成种子，种子包含三个部分：三倍体胚乳、二倍体胚和母本种皮。其中，胚乳在协调种子生长中起关键作用。丝裂原活化蛋白激酶（MAPK）级联在真核生物中保守，并参与植物发育的信号转导。MPK3、MPK6和MPK10在……中形成一个小的MPK家族亚群。MPK3和MPK6已得到广泛研究，发现它们参与包括植物繁殖在内的多种过程。然而，关于MPK10的功能了解较少。在此，我们发现……，它是参与胚乳发育的HAIKU（IKU）途径的一个成员，且在胚乳发育早期高特异性表达，但呈相反梯度。我们进一步证明MPK10和WRKY10相互交叉抑制对方的表达。MPK10与WRKY10相互作用并抑制WRKY10的转录活性，这一事实支持了MPK10对……及其下游靶标的基因表达的抑制作用。持续地，……突变体产生大种子，而……正向调节种子生长。总之，我们的数据提供了一个WRKY10和MPK10通过独特的交叉抑制机制调节胚乳发育的模型。
