Pollen tube growth and guidance is regulated by POP2, an Arabidopsis gene that controls GABA levels

Ravishankar Palanivelu, Laura Brass, Anna F. Edlund, Daphne Preuss

Research output: Contribution to journalArticle

351 Scopus citations


During angiosperm reproduction, pollen grains form a tube that navigates through female tissues to the micropyle, delivering sperm to the egg; the signals that mediate this process are poorly understood. Here, we describe a role for γ-amino butyric acid (GABA) in pollen tube growth and guidance. In vitro, GABA stimulates pollen tube growth, although vast excesses are inhibitory. The Arabidopsis POP2 gene encodes a transaminase that degrades GABA and contributes to the formation of a gradient leading up to the micropyle. pop2 flowers accumulate GABA, and the growth of many pop2 pollen tubes is arrested, consistent with their in vitro GABA hypersensitivity. Some pop2 tubes continue to grow toward ovules, yet they are misguided, presumably because they target ectopic GABA on the ovule surface. Interestingly, wild-type tubes exhibit normal growth and guidance in pop2 pistils, perhaps by degrading excess GABA and sharpening the gradient leading to the micropyle.

Original languageEnglish (US)
Pages (from-to)47-59
Number of pages13
Issue number1
Publication statusPublished - Jul 11 2003
Externally publishedYes


ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology

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