Upon gamete fusion, animal egg cells secrete proteases from cortical granules to establish a fertilization envelope as a block to polyspermy^1,2,3,4. Fertilization in flowering plants is more complex and involves the delivery of two non-motile sperm cells by pollen tubes^5,6. Simultaneous penetration of ovules by multiple pollen tubes (polytubey) is usually avoided, thus indirectly preventing polyspermy^7,8. 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.

配子融合后，动物卵细胞从皮质颗粒分泌蛋白酶，以建立受精包膜作为多精^1,2,3,4的块。开花植物的受精更为复杂，涉及通过花粉管^5,6输送两个非运动精子细胞。通常可以避免多个花粉管（polytubey）同时穿透胚珠，从而间接防止多精症^7,8。尚不清楚植物卵细胞在成功受精后如何调节对多余管子的排斥。在这里，我们报告天冬氨酸内肽酶 ECS1 和 ECS2 从位于拟南芥顶端区域的皮质网络分泌到细胞外空间。卵细胞。这种反应只有在受精成功后才会触发。ECS1和ECS2仅在卵细胞中表达，转录本在配子融合后立即降解。ECS1 和 ESC2 专门切割花粉管吸引子 LURE1。因此，多管型在ecs1 ecs2双突变体中很常见。这些来自增效细胞的内肽酶的异位分泌导致 LURE1 水平降低并降低了花粉管吸引率。总之，这些发现表明植物卵细胞感知成功受精，并阐明了一种机制，即受精诱导的吸引因子降解如何建立相对快速的多管受精后阻滞。