北京大学邓兴旺教授在PNAS杂志报道幼苗如何破土而出

幼苗能够在各种深埋条件下适应土壤环境并获得光合自养能力，对于陆生开花植物而言是个生死攸关的问题。

陆地种子植物的早期生活往往是从黑暗的土壤下开始。随着时间推移，通过适应植物进化出精细的黄化过程使得幼苗能够破土而出，获得自养能力。但这一过程要求幼苗能够感知土壤条件，从而传递这一信息以调节幼苗生长和光合器形成。但目前对于土壤覆盖驱动植物形态发生改变，尤其是响应各种的土壤条件协调不同器官细胞过程的机制的机制仍然不是很清楚。

研究人员在新研究中证实土壤覆盖激活了幼苗生成乙烯，EIN3/EIL1依赖性的乙烯响应级联反应是幼苗成功破土而出的必要条件。在土壤下，下胚轴中的ERF1信号通路激活减慢了细胞伸长，而在子叶中PIF3信号通路激活控制了光合器预装配。

此外，EIN3/EIL1引导PIF3- ERF1分子回路使得幼苗同步了黄化质体成熟与下胚轴生长的速度，最终转而使得幼苗能够在由暗向明过渡过程中维持快速获得光合自养能力所需的原叶绿素酸酯量，避免了光氧化损伤。

这些研究结果指出了一条驱动土壤诱导植物形态形成的遗传信号通路，并确定了在拟南芥幼苗中乙烯发挥特殊作用，协调了器官特异性的土壤反应。

作者简介：

邓兴旺(Xing Wang Deng)教授，北京大学。邓兴旺教授是世界著名的生物学家，其长期从事植物分子遗传及生理学方面的研究，多次在Cell、science、Nature等世界权威刊物上发表很有影响的学术文章。于去年当选为美国科学院院士。

原文摘要：

Ethylene-orchestrated circuitry coordinates a seedling’s response to soil cover and etiolated growth

Shangwei Zhong,Hui Shi, Chang Xue, Ning Wei, Hongwei Guo and Xing Wang Deng

The early life of terrestrial seed plants often starts under the soil in subterranean darkness. Over time and through adaptation, plants have evolved an elaborate etiolation process that enables seedlings to emerge from soil and acquire autotrophic ability. This process, however, requires seedlings to be able to sense the soil condition and relay this information accordingly to modulate both the seedlings’ growth and the formation of photosynthetic apparatus. The mechanism by which soil overlay drives morphogenetic changes in plants, however, remains poorly understood, particularly with regard to the means by which the cellular processes of different organs are coordinated in response to disparate soil conditions. Here, we illustrate that the soil overlay quantitatively activates seedlings’ ethylene production, and an EIN3/EIN3-like 1–dependent ethylene-response cascade is required for seedlings to successfully emerge from the soil. Under soil, an ERF1 pathway is activated in the hypocotyl to slow down cell elongation, whereas a PIF3 pathway is activated in the cotyledon to control the preassembly of photosynthetic machinery. Moreover, this latter PIF3 pathway appears to be coupled to the ERF1-regulated upward-growth rate. The coupling of these two pathways facilitates the synchronized progression of etioplast maturation and hypocotyl growth, which, in turn, ultimately enables seedlings to maintain the amount of protochlorophyllide required for rapid acquisition of photoautotrophic capacity without suffering from photooxidative damage during the dark-to-light transition. Our findings illustrate the existence of a genetic signaling pathway driving soil-induced plant morphogenesis and define the specific role of ethylene in orchestrating organ-specific soil responses in Arabidopsisseedlings.

标签: 乙烯响应级联反应 幼苗破土 EIN3/EIL1

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