MID1-COMPLEMENTING ACTIVITY (MCA) is a land plant-specific, plasma membrane protein and Ca2+ signaling component that responds to exogenous mechanical stimuli, such as touch, gravity, and hypotonic-osmotic stress, in various plant species. MCA is essential for cell proliferation and differentiation during growth and development in rice (Oryza sativa) and maize (Zea mays). However, the mechanism by which MCA mediates cell proliferation and differentiation via Ca2+ signaling remains unknown. Here, we address this question using the liverwort Marchantia polymorpha. We show that the M. polymorpha MCA ortholog, MpMCA, is highly expressed in actively dividing regions, such as apical notches in the thalli and developing gametangiophores, and that MpMCA is a plasma membrane protein. In vivo Ca2+ imaging using a Ca2+ sensor (yellow cameleon) revealed that MpMCA is required for maintaining proper [Ca2+]cyt levels in the apical notch region, egg cells, and antheridium cells. Mpmca mutant plants showed severe cell proliferation and differentiation defects in the thalli, gametangiophores, and gametangia, resulting in abnormal development and unsuccessful fertilization. Furthermore, expression of the Arabidopsis MCA1 gene complemented most of the defects in the growth and development of the Mpmca mutant plants. Our findings indicate that MpMCA is an evolutionarily conserved Ca2+-signaling component that regulates cell proliferation and development across the life cycle of land plants.

中文翻译：

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MID1 互补活性通过 Marchantia polymorpha 中的 Ca2+ 信号传导调节细胞增殖和发育


MID1-COMPLEMENTARY ACTIVITY （MCA） 是一种陆地植物特异性质膜蛋白和 Ca2+ 信号转导组分，可响应各种植物物种中的外源性机械刺激，例如触摸、重力和低渗渗透应激。MCA 对于水稻 （Oryza sativa） 和玉米 （Zea mays） 生长发育过程中的细胞增殖和分化至关重要。然而，MCA 通过 Ca2+ 信号传导介导细胞增殖和分化的机制仍然未知。在这里，我们使用地钱 Marchantia polymorpha 来解决这个问题。我们表明，M. polymorpha MCA 直系同源物 MpMCA 在活跃的分裂区域高度表达，例如菌体的顶端切迹和发育中的配子囊，并且 MpMCA 是一种质膜蛋白。使用 Ca2+ 传感器（黄色骆驼）的体内 Ca2+ 成像显示，MpMCA 是维持顶端切迹区域、卵细胞和花药细胞中适当的 [Ca2+] 细胞水平所必需的。Mpmca 突变植物在菌体、配子体和配子中表现出严重的细胞增殖和分化缺陷，导致发育异常和受精不成功。此外，拟南芥 MCA1 基因的表达补充了 Mpmca 突变植物生长发育中的大部分缺陷。我们的研究结果表明，MpMCA 是一种进化上保守的 Ca2+ 信号转导成分，可在陆地植物的整个生命周期中调节细胞增殖和发育。