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研究发现植物如何避免重复受精
2021-04-01 15:11

武汉大学孙蒙祥、德国雷根斯堡大学Thomas Dresselhaus等研究人员合作发现,植物的受精卵细胞通过分泌内肽酶来避免重复受精。相关论文于2021年3月31日发表在《自然》杂志上。

研究人员发现,天冬氨酸内肽酶ECS1和ECS2是从位于拟南芥卵细胞顶端结构域的皮层网络分泌到细胞外空间的。仅在成功受精后才触发该反应。ECS1和ECS2仅在卵细胞中表达,并且配子融合后,转录本立即降解。ECS1和ESC2专门切割花粉管吸引分子LURE1。所以,在ecs1 ecs2双重突变体中多管现象很常见。这些内肽酶从协同细胞中的异位分泌导致LURE1的水平降低,并降低了花粉管的吸引率。

总之,这些发现表明植物卵细胞能够感知成功的受精,并阐明了受精引起的吸引因子降解如何建立相对快速的受精后阻遏机制。 

据介绍,配子融合后,动物卵细胞从皮质颗粒分泌蛋白酶,建立受精膜作为多精子的阻滞。开花植物中的受精更为复杂,并涉及通过花粉管传递两个非运动性精子细胞。通常避免了多个花粉管(多管)同时渗透胚珠,从而间接地阻止了多精子。成功受精后,植物卵细胞如何阻止多管形成尚不清楚。

附:英文原文

Title: Fertilized egg cells secrete endopeptidases to avoid polytubey

Author: Xiaobo Yu, Xuecheng Zhang, Peng Zhao, Xiongbo Peng, Hong Chen, Andrea Bleckmann, Anastasiia Bazhenova, Ce Shi, Thomas Dresselhaus, Meng-xiang Sun

Issue&Volume: 2021-03-31

Abstract: Upon gamete fusion, animal egg cells secrete proteases from cortical granules to establish a fertilization envelope as a block to polyspermy1,2,3,4. Fertilization in flowering plants is more complex and involves the delivery of two non-motile sperm cells by pollen tubes5,6. Simultaneous penetration of ovules by multiple pollen tubes (polytubey) is usually avoided, thus indirectly preventing polyspermy7,8. How plant egg cells regulate the rejection of extra tubes after successful fertilization is not known. Here we report that the aspartic endopeptidases ECS1 and ECS2 are secreted to the extracellular space from a cortical network located at the apical domain of the Arabidopsis egg cell. This reaction is triggered only after successful fertilization. ECS1 and ECS2 are exclusively expressed in the egg cell and transcripts are degraded immediately after gamete fusion. ECS1 and ESC2 specifically cleave the pollen tube attractor LURE1. As a consequence, polytubey is frequent in ecs1 ecs2 double mutants. Ectopic secretion of these endopeptidases from synergid cells led to a decrease in the levels of LURE1 and reduced the rate of pollen tube attraction. Together, these findings demonstrate that plant egg cells sense successful fertilization and elucidate a mechanism as to how a relatively fast post-fertilization block to polytubey is established by fertilization-induced degradation of attraction factors.

DOI: 10.1038/s41586-021-03387-5

Source: https://www.nature.com/articles/s41586-021-03387-5

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:69.504
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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