Nitrate, a signal relieving seed dormancy in  Arabidopsis.
Nitrate is an important nitrogen source for plants, but also a signal molecule that controls various aspects of plant development. In the present study the role of nitrate on seed dormancy in Arabidopsis was investigated. The effects of either mutations affecting the Arabidopsis nitrate reductase genes or of different nitrate regimes of mother plants on the dormancy of the seeds produced were analysed. Altogether, data show that conditions favouring nitrate accumulation in mother plants and in seeds lead to a lower dormancy of seeds with little other morphological or biochemical differences. Analysis of germination during seed development indicated that nitrate does not prevent the onset of dormancy but rather its maintenance. The effect of an exogenous supply of nitrate on seed germination was tested: nitrate in contrast to glutamine or potassium chloride clearly stimulated the germination of dormant seeds. Data show, moreover, that the Arabidopsis dual affinity nitrate transporter NRT1.1 (CHL1) may be involved in conveying the nitrate signal into seeds. Thus, nitrate provided exogenously or by mother plants to the produced seeds, acts as a signal molecule favouring germination in Arabidopsis. This signalling may involve interaction with the abscisic acid or gibberellin pathway.
Alboresi
A
A
Unité de Nutrition Azotée des Plantes, INRA centre de Versailles-Grignon, Versailles Cedex, France.
Gestin
C
C
Leydecker
M-T
MT
Bedu
M
M
Meyer
C
C
Truong
H-N
HN
D000040:Abscisic Acid / Q000494:pharmacology; D027321:Anion Transport Proteins / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects*; D005875:Gibberellins / Q000494:pharmacology; D005973:Glutamine / Q000494:pharmacology; D009566:Nitrates / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D011189:Potassium Chloride / Q000494:pharmacology; D012639:Seeds / Q000187:drug effects* / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects; D014230:Triazoles / Q000494:pharmacology
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; D005875:Gibberellins; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014230:Triazoles; D005973:Glutamine; D011189:Potassium Chloride; C053370:paclobutrazol; D000040:Abscisic Acid