J Integr Plant Biol ›› 2022, Vol. 64 ›› Issue (11): 2047-2059.DOI: 10.1111/jipb.13371

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  • 收稿日期:2022-09-13 接受日期:2022-09-23 出版日期:2022-11-01 发布日期:2022-11-16

Egg cell-secreted aspartic proteases ECS1/2 promote gamete attachment to prioritize the fertilization of egg cells over central cells in Arabidopsis

Jiahao Jiang1, Nils Stührwohldt2, Tianxu Liu1, Qingpei Huang1, Ling Li1, Li Zhang1, Hongya Gu1, Liumin Fan1*, Sheng Zhong1*, Andreas Schaller2* and Li-Jia Qu1*   

  1. 1 State Key Laboratory for Protein and Plant Gene Research, Peking‐Tsinghua Center for Life Sciences at College of Life Sciences, Peking University, Beijing 100871, China
    2 Department of Plant Physiology and Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart 70593, Germany

    *Correspondences: Li-Jia Qu (qulj@pku.edu.cn, Dr. Qu is fully responsible for the distributions of all materials associated with this article.); Andreas Schaller (andreas.schaller@uni-hohenheim.de); Sheng Zhong (shengshengzz@pku.edu.cn); Liumin Fan (lmfan@pku. edu.cn)
  • Received:2022-09-13 Accepted:2022-09-23 Online:2022-11-01 Published:2022-11-16

Abstract:

Double fertilization is an innovative phenomenon in angiosperms, in which one sperm cell first fuses with the egg cell to produce the embryo, and then the other sperm fuses with the central cell to produce the endosperm. However, the molecular mechanism of the preferential fertilization of egg cells is poorly understood. In this study, we report that two egg cell-secreted aspartic proteases, ECS1 and ECS2, play an important role in promoting preferential fertilization of egg cells in Arabidopsis. We show that simultaneous loss of ECS1 and ECS2 function resulted in an approximately 20% reduction in fertility, which can be complemented by the full-length ECS1/2 but not by corresponding active site mutants or by secretion-defective versions of ECS1/2. Detailed phenotypic analysis revealed that the egg cell–sperm cell attachment was compromised in ecs1 ecs2 siliques. Limited pollination assays with cyclin-dependent kinase a1 (cdka;1) pollen showed that preferential egg cell fertilization was impaired in the ecs1 ecs2 mutant. Taken together, these results demonstrate that egg cells secret two aspartic proteases, ECS1 and ECS2, to facilitate the attachment of sperm cells to egg cells so that preferential fertilization of egg cells is achieved. This study reveals the molecular mechanism of preferential fertilization in Arabidopsis thaliana.

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