title: Peptide signalling during the pollen tube journey and double fertilization.
abstract: Flowering seed plants (angiosperms) have evolved unique ways to protect their gametes from pathogen attack and from drying out. The female gametes (egg and central cell) are deeply embedded in the maternal tissues of the ovule inside the ovary, while the male gametes (sperm cells) are enclosed in the vegetative pollen tube cell. After germination of the pollen tube at the surface of papilla cells of the stigma the two immobile sperm cells are transported deep inside the sporophytic maternal tissues to be released inside the ovule for double fertilization. Angiosperms have evolved a number of hurdles along the pollen tube journey to prevent inbreeding and fertilization by alien sperm cells, and to maximize reproductive success. These pre-zygotic hybridization barriers require intensive communication between the male and female reproductive cells and the necessity to distinguish self from non-self interaction partners. General molecules such as nitric oxide (NO) or gamma-aminobutyric acid (GABA) therefore appear to play only a minor role in these species-specific communication events. The past 20 years have shown that highly polymorphic peptides play a leading role in all communication steps along the pollen tube pathway and fertilization. Here we review our current understanding of the role of peptides during reproduction with a focus on peptide signalling during self-incompatibility, pollen tube growth and guidance as well as sperm reception and gamete activation.
authors.affiliation: State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at College of Life Sciences, Peking University, Beijing 100871, China qulj@pku.edu.cn thomas.dresselhaus@ur.de.
authors.forename: Li-Jia
authors.initials: LJ
authors.lastname: Qu
authors.affiliation: State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Zijun
authors.initials: Z
authors.lastname: Lan
authors.affiliation: Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany qulj@pku.edu.cn thomas.dresselhaus@ur.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dresselhaus
mesh_terms: D019684:Magnoliopsida / Q000235:genetics / Q000502:physiology*; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D053205:Pollen Tube / Q000254:growth & development; D012098:Reproduction; D060436:Self-Incompatibility in Flowering Plants; D015398:Signal Transduction
chemical_list: D010455:Peptides; D010940:Plant Proteins
keywords: Cysteine rich peptide (CRP); fertilization; pollen tube; receptor-like kinase (RLK); reproductive isolation; self-incompatibility.