PNAS:武汉大学孙蒙祥课题组与东北地理所揭示早期植物胚胎发生

9月22日《PNAS》上在线发表武汉大学孙蒙祥课题组与中国科学院东北地理与农业生态研究所大豆分子设计育种重点实验室Xianzhong Feng组合作开展的一项研究成果。东北地理与农业生态研究所大豆功能基因组学学科组的助理研究员刘媛为该论文第一作者，武汉大学孙蒙祥教授为通讯作者。

植物胚胎分为胚体和胚柄两大结构。胚柄在植物早期胚胎发育的过程中起到支撑胚体以及向胚体输送营养物质、生长调节因子的作用。在胚胎发育过程中胚柄细胞逐渐发生细胞程序性死亡，并不参与成熟植株的绝大部分组织构建。胚柄细胞是否具有发育成为胚胎的潜能一直是早期胚胎发育过程中的研究热点问题。

上世纪60年代开始，就有科学家提出假说认为胚柄的胚胎发育前被胚体所抑制，但虽经许多科学家们利用多种方法进行长期研究，一直没有明确的结论。中国科学院东北地理与农业生态研究所大豆分子设计育种重点实验室与武汉大学课题组合作开展对这一课题的研究，研究人员采用活体体内激光切割系统在拟南芥胚珠内切断胚体胚柄的联系，培养后发现部分胚柄能够发育成为一个新的胚胎，给出了胚柄的胚胎发育潜能是被胚体抑制的最直接证据。该研究还发现生长素的极性运输在胚体抑制胚柄细胞胚胎潜能的过程中起了重要的作用。美国科学院院刊编委会认为这篇论文对于早期胚胎发育领域的研究做出了重要的贡献。

原文链接：

Direct evidence that suspensor cells have embryogenic potential that is suppressed by the embryo proper during normal embryoGENEsis

原文摘要：

The suspensor is a temporary supporting structure of proembryos. It has been proposed that suspensor cells also possess embryogenic potential, which is suppressed by the embryo as an effect of the embryo–suspensor interaction. However, data to support this hypothesis are not yet available. In this report, using an in vivo living cell laser ablation technique, we show that Arabidopsis suspensor cells can develop into embryos after removing the embryo proper. The embryo proper plays a critical role in maintaining suspensor cell identity. However, this depends on the developmental stage; after the globular embryo stage, the suspensors no longer possess the potential to develop into embryos. We also reveal that hypophysis formation may be essential for embryo differentiation. Furthermore, we show that, after removing the embryo, auxin gradually accumulates in the top suspensor cell where cell division occurs to produce an embryo. Auxin redistribution likely reprograms the fate of the suspensor cell and triggers embryogenesis in suspensor cells. Thus, we provide direct evidence that the embryo suppresses the embryogenic potential of suspensor cells.

doi: 10.1073/PNAS.1508651112

作者：孙蒙祥