The kinase ERULUS controls pollen tube targeting and growth in Arabidopsis thaliana
Pollen cells have a fascinating ability to transform from a small spherical cell to a very elongated shape known as the pollen tube (PT) during fertilization. Pollen cells must navigate through the female tissue, find an ovary, and burst to release the two sperm cell nuclei as well as the vegetative nucleus, a process dependent upon calcium sensing and signaling. Schoenaers et al. identify a key player in this process, the receptor-like kinase ERULUS (ERU). Mutant pollen grown under low calcium conditions displayed decreased growth rates. Calcium FRET image analysis showed that the canonical calcium oscillations observed at the tips of growing PTs were altered in eru pollen grown on low calcium media. Aberrant calcium oscillations resulted in defective PT targeting in eru mutants. Furthermore, heterozygous eru plants undergoing self-fertilization deviated from expected Mendelian inheritance, with less homozygous eru progeny seen. These data show a role for ERU in calcium sensing, PT targeting, and fertilization. (Summary by Alecia Biel) Front Plant Sci. 10.3389/fpls.2017.01942.