title: Role of proline and GABA in sexual reproduction of angiosperms.
abstract: Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabidopsis mutants affected in the first and rate-limiting step in proline synthesis produce aberrant and infertile pollen grains, indicating that proline synthesis is required for pollen development and fertility. Concerning GABA, a large body of evidence points to this glutamate derivative as a key determinant of post-pollination fertilization. Intriguingly, proline has also been associated with pollination, another aspect of sexual reproduction, since honeybees were reported to show a strong preference for proline-enriched nectars. In this review, we survey current knowledge on the roles of proline and GABA in plant fertility, and discuss future perspectives potentially capable to improve our understanding on the functions of these amino acids in pollen development, pollination, and pollen tube guidance.
authors.affiliation: Department of Biology and Biotechnology, Sapienza University of Rome Roma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Biancucci
authors.affiliation: Department of Biology and Biotechnology, Sapienza University of Rome Roma, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Mattioli
authors.affiliation: Department of Life Science and Biotechnology, University of Ferrara Ferrara, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Forlani
authors.affiliation: Department of Biology, University of Konstanz Konstanz, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Funck
authors.affiliation: Department of Biology and Biotechnology, Sapienza University of Rome Roma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Costantino
authors.affiliation: Department of Biology and Biotechnology, Sapienza University of Rome Roma, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Trovato
keywords: Arabidopsis; GABA; P5CS1; P5CS2; anthers; pollen; proline; sexual plant reproduction