title: Defensin-like polypeptide LUREs are pollen tube attractants secreted from synergid cells.
abstract: For more than 140 years, pollen tube guidance in flowering plants has been thought to be mediated by chemoattractants derived from target ovules. However, there has been no convincing evidence of any particular molecule being the true attractant that actually controls the navigation of pollen tubes towards ovules. Emerging data indicate that two synergid cells on the side of the egg cell emit a diffusible, species-specific signal to attract the pollen tube at the last step of pollen tube guidance. Here we report that secreted, cysteine-rich polypeptides (CRPs) in a subgroup of defensin-like proteins are attractants derived from the synergid cells. We isolated synergid cells of Torenia fournieri, a unique plant with a protruding embryo sac, to identify transcripts encoding secreted proteins as candidate molecules for the chemoattractant(s). We found two CRPs, abundantly and predominantly expressed in the synergid cell, which are secreted to the surface of the egg apparatus. Moreover, they showed activity in vitro to attract competent pollen tubes of their own species and were named as LUREs. Injection of morpholino antisense oligomers against the LUREs impaired pollen tube attraction, supporting the finding that LUREs are the attractants derived from the synergid cells of T. fournieri.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Satohiro
authors.initials: S
authors.lastname: Okuda
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tsutsui
authors.forename: Keiko
authors.initials: K
authors.lastname: Shiina
authors.forename: Stefanie
authors.initials: S
authors.lastname: Sprunck
authors.forename: Hidenori
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Ryoko
authors.initials: R
authors.lastname: Yui
authors.forename: Ryushiro D
authors.initials: RD
authors.lastname: Kasahara
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hamamura
authors.forename: Akane
authors.initials: A
authors.lastname: Mizukami
authors.forename: Daichi
authors.initials: D
authors.lastname: Susaki
authors.forename: Nao
authors.initials: N
authors.lastname: Kawano
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakakibara
authors.forename: Shoko
authors.initials: S
authors.lastname: Namiki
authors.forename: Kie
authors.initials: K
authors.lastname: Itoh
authors.forename: Kurataka
authors.initials: K
authors.lastname: Otsuka
authors.forename: Motomichi
authors.initials: M
authors.lastname: Matsuzaki
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Nozaki
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
authors.forename: Masahiro M
authors.initials: MM
authors.lastname: Kanaoka
authors.forename: Thomas
authors.initials: T
authors.lastname: Dresselhaus
authors.forename: Narie
authors.initials: N
authors.lastname: Sasaki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higashiyama
mesh_terms: D000595:Amino Acid Sequence; D002630:Chemotactic Factors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D023082:Defensins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D020224:Expressed Sequence Tags; D019684:Magnoliopsida / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000235:genetics; D053205:Pollen Tube / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D018749:RNA, Plant / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D002630:Chemotactic Factors; D023082:Defensins; D016376:Oligonucleotides, Antisense; D018749:RNA, Plant