英国诺丁汉大学Michael J. Holdsworth研究小组取得一项新突破。他们揭示了被子植物适应海拔的氧气传感机制。这一研究成果于2022年6月1日发表在国际学术期刊《自然》上。

研究人员探究了海拔和氧气感应与叶绿素生物合成（需要分子氧）和缺氧相关基因表达之间的关系。研究发现，在被子植物的黄化幼苗中，光毒性叶绿素前体原叶绿素的稳态水平受到大气氧浓度传感的影响。在拟南芥中，这是由植物半胱氨酸氧化酶(PCO) N-degron途径底物第VII组乙烯反应因子转录因子(ERFVII)所介导。ERFVIIs正向调节FLUORESCENT IN BLUE LIGHT (FLU)的表达，它抑制叶绿素生物合成的第一个关键步骤，与受ERFVIIs负调节的四吡咯合成酶形成失活复合物，从而抑制原叶绿素合成。

在不同被子植物进化枝的自然种群中，研究发现原叶绿素的稳态水平、失活复合物成分和缺氧相关基因的表达依赖于氧气的海拔高度分布。最后，通过对比不同海拔的拟南芥种质，它们表现出依赖于海拔的ERFVII活性和积累。因此，该研究通过改变氧传感系统的敏感性确定了植物适应绝对高度的遗传机制。

研究人员表示，开花植物（被子植物）可以在极端的海拔高度生长，并且已观察到有被子植物可以在海拔6,400米生长；然而，植物适应海拔高度的分子机制尚不清楚。海拔升高的一个显著特征是氧气分压(pO2)的降低。

附：英文原文

Title: An oxygen-sensing mechanism for angiosperm adaptation to altitude

Author: Abbas, Mohamad, Sharma, Gunjan, Dambire, Charlene, Marquez, Julietta, Alonso-Blanco, Carlos, Proao, Karina, Holdsworth, Michael J.

Issue&Volume: 2022-06-01

Abstract: Flowering plants (angiosperms) can grow at extreme altitudes, and have been observed growing as high as 6,400 metres above sea level1,2; however, the molecular mechanisms that enable plant adaptation specifically to altitude are unknown. One distinguishing feature of increasing altitude is a reduction in the partial pressure of oxygen (pO2). Here we investigated the relationship between altitude and oxygen sensing in relation to chlorophyll biosynthesis—which requires molecular oxygen3—and hypoxia-related gene expression. We show that in etiolated seedlings of angiosperm species, steady-state levels of the phototoxic chlorophyll precursor protochlorophyllide are influenced by sensing of atmospheric oxygen concentration. In Arabidopsis thaliana, this is mediated by the PLANT CYSTEINE OXIDASE (PCO) N-degron pathway substrates GROUP VII ETHYLENE RESPONSE FACTOR transcription factors (ERFVIIs). ERFVIIs positively regulate expression of FLUORESCENT IN BLUE LIGHT (FLU), which represses the first committed step of chlorophyll biosynthesis, forming an inactivation complex with tetrapyrrole synthesis enzymes that are negatively regulated by ERFVIIs, thereby suppressing protochlorophyllide. In natural populations representing diverse angiosperm clades, we find oxygen-dependent altitudinal clines for steady-state levels of protochlorophyllide, expression of inactivation complex components and hypoxia-related genes. Finally, A. thaliana accessions from contrasting altitudes display altitude-dependent ERFVII activity and accumulation. We thus identify a mechanism for genetic adaptation to absolute altitude through alteration of the sensitivity of the oxygen-sensing system.

DOI: 10.1038/s41586-022-04740-y

Source: https://www.nature.com/articles/s41586-022-04740-y