AtNSE1 and AtNSE3 are required for embryo pattern formation and maintenance of cell viability during Arabidopsis embryogenesis
AtNSE1 and AtNSE3 are required for embryo pattern formation and maintenance of cell viability during Arabidopsis embryogenesis
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DOI：
10.1093/jxb/erz373
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发表时间：
2019-08
影响因子：
6.9
通讯作者：
Gang Li;Wenxuan Zou;Liufang Jian;J. Qian;Jie Zhao
中科院分区：
文献类型：
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作者：
Gang Li;Wenxuan Zou;Liufang Jian;J. Qian;Jie Zhao
摘要 胚胎发生是高等植物种子发育过程中的一个重要过程。此前已有研究表明，拟南芥非SMC元件基因AtNSE1或AtNSE3的突变会导致早期胚胎败育，并且它们的蛋白质可以直接相互作用。然而，这些蛋白质在这种相互作用中的关键区域以及这些蛋白质如何在细胞学上参与拟南芥胚胎发育尚不清楚。在本研究中，我们发现AtNSE1的C端包含环状基序可以与AtNSE3的N端相互作用，并且只有环状基序对于与AtNSE2（与AtMMS21同源）的三个α基序的结合是必需的。使用遗传测定并通过分析突变型 nse1 和 nse3 胚胎中细胞命运决定的分子标记（STM、WOX5 和 WOX8），我们发现 AtNSE1 和 AtNSE3 在早期胚胎发育中非冗余地发挥作用，并且突变体中顶端分生组织和垂体的分化失败，这扰乱了生长素的运输和反应。然而，突变体中胚柄的上部细胞似乎具有正确的胚胎细胞身份。细胞学检查显示，细胞死亡从胚胎早期就发生，nse1和nse3突变胚胎中的液泡程序性细胞死亡和坏死导致胚珠败育。因此，AtNSE1 和 AtNSE3 对于维持早期胚胎发生过程中的细胞活力和生长至关重要。我们的结果提高了我们对 SMC5/6 复合物在拟南芥早期胚胎发生中的功能的理解。
Abstract Embryogenesis is an essential process during seed development in higher plants. It has previously been shown that mutation of the Arabidopsis non-SMC element genes AtNSE1 or AtNSE3 leads to early embryo abortion, and their proteins can interact with each other directly. However, the crucial regions of these proteins in this interaction and how the proteins are cytologically involved in Arabidopsis embryo development are unknown. In this study, we found that the C-terminal including the Ring-like motif of AtNSE1 can interact with the N-terminal of AtNSE3, and only the Ring-like motif is essential for binding with three α motifs of AtNSE2 (homologous to AtMMS21). Using genetic assays and by analysing molecular markers of cell fate decisions (STM, WOX5, and WOX8) in mutant nse1 and nse3 embryos, we found that AtNSE1 and AtNSE3 work non-redundantly in early embryo development, and that differentiation of the apical meristem and the hypophysis fails in the mutants, which have disrupted auxin transportation and responses. However, the upper cells of the suspensor in the mutants seem to have proper embryo cell identity. Cytological examination showed that cell death occurred from the early embryo stage, and that vacuolar programmed cell death and necrosis in the nse1 and nse3 mutant embryos led to ovule abortion. Thus, AtNSE1 and AtNSE3 are essential for maintaining cell viability and growth during early embryogenesis. Our results improve our understanding of the functions of SMC5/6 complex in early embryogenesis in Arabidopsis.