Defensin-like polypeptide LUREs are pollen tube attractants secreted from synergid cells.
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.
Okuda
Satohiro
S
Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
Tsutsui
Hiroki
H
Shiina
Keiko
K
Sprunck
Stefanie
S
Takeuchi
Hidenori
H
Yui
Ryoko
R
Kasahara
Ryushiro D
RD
Hamamura
Yuki
Y
Mizukami
Akane
A
Susaki
Daichi
D
Kawano
Nao
N
Sakakibara
Takashi
T
Namiki
Shoko
S
Itoh
Kie
K
Otsuka
Kurataka
K
Matsuzaki
Motomichi
M
Nozaki
Hisayoshi
H
Kuroiwa
Tsuneyoshi
T
Nakano
Akihiko
A
Kanaoka
Masahiro M
MM
Dresselhaus
Thomas
T
Sasaki
Narie
N
Higashiyama
Tetsuya
T
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
D002630:Chemotactic Factors; D023082:Defensins; D016376:Oligonucleotides, Antisense; D018749:RNA, Plant