a, In flowering plants, sperm-containing pollen grains land on the receptive stigma of the female reproductive organ (the pistil), and form pollen tubes that grow towards egg-bearing structures called female gametophytes, which are located in ovules. Paired synergid cells in the female gametophyte release molecules such as AtLURE1 that attract the tubes. When the pollen tube penetrates a synergid, it ruptures, releasing two sperm for fertilization. b, Wang et al.3 and Takeuchi and Higashiyama4 have identified receptor-like kinase (RLK) proteins on pollen tubes that are involved in ovule targeting. Wang et al. showed that AtLURE1 binds the RLKs MIK1 and MDIS1, promoting their dimerization and inducing MIK1 to add phosphate groups (P) to itself and to MDIS1. Takeuchi and Higashiyama showed that the RLK PRK6 interacts with itself and PRK3, and with guanine-exchange factors (GEFs) that activate Rho GTPase proteins from plants (ROPs), leading to ovule targeting.