日前，北京大学钟上威和邓兴旺课题组发现植物幼苗感应土壤中光照强度变化的核心功能蛋白，并揭示了出土过程中幼苗感知土壤深度变化而相应调整其生长发育的分子信号通路。相关成果发布于《现代生物学》。 土壤中生长的幼苗受多种因素调控，比如光照、温度、土壤机械压力等，但由于土壤成分复杂，人们之前对土壤中植物生长发育怎样被调控的分子机理知之甚少。

科研人员通过土壤覆盖实验和分子遗传筛选，发现了一个进化上高度保守的泛素连接酶COP1在幼苗出土过程中起着核心作用。COP1单基因突变将导致幼苗不能出土存活，且在遗传上位于转录因子上游，保护和维持着其功能。前期工作发现，土壤机械压力能诱导幼苗生成植物激素乙烯，并通过稳定一种蛋白协调幼苗子叶与下胚轴的生长发育，促进幼苗出土变绿存活。该研究进一步确定COP1与乙烯是相互独立的两条信号通路，共同调控着蛋白水平。

该研究揭示了植物幼苗出土过程中感知土壤环境变化的核心功能基因与分子调控机理。研究成果加深了对幼苗出土这一自然现象的认识，也为农业生产中提高农作物幼苗出土存活效率提供了理论基础。（来源：中国科学报 彭科峰）

Seedlings Transduce the Depth and Mechanical Pressure of Covering Soil Using COP1 and Ethylene to Regulate EBF1/EBF2 for Soil Emergence

Abstract  The survival of seed plants in natural environments requires the successful emergence from the soil. In this process, the ethylene signaling pathway is utilized by plants to sense and respond to the mechanical resistance of the soil. Here, we report that constitutive photomorphogenesis 1 (COP1), a central repressor of light signaling, is a key component required for seedlings to sense the depth of soil overlay. Mutation in COP1 causes severe defects in penetrating soil, due to decreased level of EIN3, a master transcription factor in ethylene pathway that mediates seedling emergence. We show that COP1 directly targets the F box proteins EBF1 and EBF2 for ubiquitination and degradation, thus stabilizing EIN3. As seedlings grow toward the surface, the depth of soil overlay decreases, resulting in a gradual increase of light fluences. COP1 channels the light signals, while ethylene transduces the information on soil mechanical conditions, which cooperatively control EIN3 protein levels to promote seedling emergence from the soil. The COP1-EBF1/2-EIN3 module reveals a mechanism by which plants sense the depth to surface and uncovers a novel regulatory paradigm of an ubiquitin E3 ligase cascade.

原文链接：http://www.sciencedirect.com/science/article/pii/S0960982215014979