Complex regulation of plant sex by peptides

How the pollen tube is regulated to deliver sperm cells to produce seeds is characterized Most of our food—whether fruit or grain—is the direct result of flowering plant fertilization. As this also underlies the transmission of genetic information over generations, it is essential to understand the molecular events controlling plant reproduction. During fertilization, pollen (the male gametophyte, or reproductive cell) forms a pollen tube which is guided toward the ovule (the female gametophyte), where, upon bursting, it will deliver its sperm cells ( 1 ). All steps—from the perception of compatible pollens by the flower pistil (the female reproductive organ) to pollen tube growth, guidance and, ultimately, rupture—are controlled by a complex molecular dialogue involving numerous plant receptor kinases and endogenous signaling molecules, including secreted peptides ( 2 ). On pages 1596 and 1600 of this issue, Ge et al. ( 3 ) and Mecchia et al. ( 4 ), respectively, characterize signaling events between the male and female gametophytes, which offer exciting insights into the molecular mechanisms controlling plant fertilization and seed setting.