Paper of the month (April 2014)

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Reactive oxygen species mediate pollen tube rupture to release sperm for fertilization in Arabidopsis

Qiaohong Duan, Daniel Kita, Eric A. Johnson, Mini Aggarwal, Laura Gates, Hen-Ming Wu & Alice Y. Cheung

Department of Biochemistry and Molecular Biology, University of Massachusetts, 710N. Pleasant Street, Lederle Graduate Research Tower, Amherst, Massachusetts 01003, USA

Reference: Duan et al (2014) Nature Communications, 5: 3129.

Summary

In flowering plants, sperm are transported inside pollen tubes to the female gametophyte for fertilization. The female gametophyte induces rupture of the penetrating pollen tube, resulting in sperm release and rendering them available for fertilization. Here we utilize the Arabidopsis FERONIA (FER) receptor kinase mutants, whose female gametophytes fail to induce pollen tube rupture, to decipher the molecular mechanism of this critical male–female interactive step. We show that FER controls the production of high levels of reactive oxygen species at the entrance to the female gametophyte to induce pollen tube rupture and sperm release. Pollen tube growth assays in vitro and in the pistil demonstrate that hydroxyl free radicals are likely the most reactive oxygen molecules, and they induce pollen tube rupture in a Ca2þ- dependent process involving Ca2þ channel activation. Our results provide evidence for a RHO GTPase-based signalling mechanism to mediate sperm release for fertilization in plants.

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