Animal fertilization relies on hundreds of sperm racing toward the egg, whereas, in angiosperms, only two sperm cells are delivered by a pollen tube to the female gametes (egg cell and central cell) for double fertilization. However, unsuccessful fertilization under this one-pollen-tube design can be detrimental to seed production and plant survival. To mitigate this risk, unfertilized-gamete-controlled extra pollen tube entry has been evolved to bring more sperm cells and salvage fertilization. Despite its importance, the underlying molecular mechanism of this phenomenon remains unclear. In this study, we report that, in Arabidopsis, the central cell secretes peptides SALVAGER1 and SALVAGER2 in a directional manner to attract pollen tubes when the synergid-dependent attraction fails or is terminated by pollen tubes carrying infertile sperm cells. Moreover, loss of SALs impairs the fertilization recovery capacity of the ovules. Therefore, this research uncovers a female gamete-attraction system that salvages seed production for reproductive assurance.

动物受精依赖于数百个精子奔向卵子，而在被子植物中，只有两个精子细胞通过花粉管传递到雌配子（卵细胞和中央细胞）进行双重受精。然而，在这种单花粉管设计下的不成功受精可能不利于种子生产和植物存活。为了减轻这种风险，未受精配子控制的额外花粉管进入已经进化，以带来更多精子细胞和挽救受精。尽管它很重要，但这种现象的潜在分子机制仍不清楚。在这项研究中，我们报道，在拟南芥中，当助剂依赖性吸引失败或被携带不育精子细胞的花粉管终止时，中央细胞以定向方式分泌肽SALVAGER1和SALVAGER2来吸引花粉管。此外，SAL会损害胚珠的受精恢复能力。因此，这项研究揭示了一种雌配子吸引系统，可以挽救种子生产以保证生殖。