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First, the number of progeny inheriting a dominant sulfadiazine resistance marker linked to <jats:italic>p5cs2<\/jats:italic> was determined. Second, the number of <jats:italic>p5cs2\/p5cs2<\/jats:italic> embryos was determined. A ratio of resistant to susceptible plantlets close to 50%, and the absence of aborted embryos were consistent with the hypothesis that the male gametophyte carrying both <jats:italic>p5cs1<\/jats:italic> and <jats:italic>p5cs2<\/jats:italic> alleles is rarely transmitted to the offspring. In addition, in reciprocal crosses with wild type, about 50% of the <jats:italic>p5cs2<\/jats:italic> mutant alleles were transmitted to the sporophytic generation when <jats:italic>p5cs1 p5cs2\/P5CS2<\/jats:italic> was used as a female, while less than 1% of the <jats:italic>p5cs2<\/jats:italic> alleles could be transmitted to the outcrossed progeny when <jats:italic>p5cs1 p5cs2\/P5CS2<\/jats:italic> was used as a male. Morphological and functional analysis of mutant pollen revealed a population of small, degenerated, and unviable pollen grains, indicating that the mutant homozygous for <jats:italic>p5cs1<\/jats:italic> and heterozygous for <jats:italic>p5cs2<\/jats:italic> is impaired in pollen development, and suggesting a role for proline in male gametophyte development. Consistent with these findings, we found that pollen from <jats:italic>p5cs1<\/jats:italic> homozygous mutants, display defects similar to, but less pronounced than pollen from <jats:italic>p5cs1 p5cs2\/P5CS2<\/jats:italic> mutants. Finally, we show that pollen from <jats:italic>p5cs1 p5cs2\/P5CS2<\/jats:italic> plants contains less proline than wild type and that exogenous proline supplied from the beginning of another development can partially complement both morphological and functional pollen defects.<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Conclusions<\/jats:title>\n            <jats:p>Our data show that the development of the male gametophyte carrying mutations in both <jats:italic>P5CS1<\/jats:italic> and <jats:italic>P5CS2<\/jats:italic> is severely compromised, and indicate that proline is required for pollen development and transmission.<\/jats:p>\n          <\/jats:sec>","DOI":"10.1186\/1471-2229-12-236","type":"journal-article","created":{"date-parts":[[2012,12,12]],"date-time":"2012-12-12T11:14:23Z","timestamp":1355310863000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":86,"title":["Proline is required for male gametophyte development in Arabidopsis"],"prefix":"10.1186","volume":"12","author":[{"given":"Roberto","family":"Mattioli","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marco","family":"Biancucci","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chiara","family":"Lonoce","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paolo","family":"Costantino","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maurizio","family":"Trovato","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2012,12,12]]},"reference":[{"key":"1178_CR1","doi-asserted-by":"publisher","first-page":"72","DOI":"10.1111\/j.1399-3054.2009.01261.x","volume":"137","author":"R Mattioli","year":"2009","unstructured":"Mattioli R, Falasca G, Sabatini S, Costantino P, Altamura MM, Trovato M: The proline biosynthetic genes P5CS1 and P5CS2 play overlapping roles in Arabidopsis flower transition but not in embryo development. 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