The Arabidopsis abscisic acid catabolic gene CYP707A2 plays a key role in nitrate control of seed dormancy.
Nitrate releases seed dormancy in Arabidopsis (Arabidopsis thaliana) Columbia accession seeds in part by reducing abscisic acid (ABA) levels. Nitrate led to lower levels of ABA in imbibed seeds when included in the germination medium (exogenous nitrate). Nitrate also reduced ABA levels in dry seeds when provided to the mother plant during seed development (endogenous nitrate). Transcript profiling of imbibed seeds treated with or without nitrate revealed that exogenous nitrate led to a higher expression of nitrate-responsive genes, whereas endogenous nitrate led to a profile similar to that of stratified or after-ripened seeds. Profiling experiments indicated that the expression of the ABA catabolic gene CYP707A2 was regulated by exogenous nitrate. The cyp707a2-1 mutant failed to reduce seed ABA levels in response to both endogenous and exogenous nitrate. In contrast, both endogenous and exogenous nitrate reduced ABA levels of the wild-type and cyp707a1-1 mutant seeds. The CYP707A2 mRNA levels in developing siliques were positively correlated with different nitrate doses applied to the mother plants. This was consistent with a role of the CYP707A2 gene in controlling seed ABA levels in response to endogenous nitrate. The cyp707a2-1 mutant was less sensitive to exogenous nitrate for breaking seed dormancy. Altogether, our data underline the central role of the CYP707A2 gene in the nitrate-mediated control of ABA levels during seed development and germination.
Matakiadis
Theodoros
T
Unité de la Nutrition Azotée des Plantes, Institut Jean-Pierre Bourgin, INRA, 78026 Versailles cedex, France.
Alboresi
Alessandro
A
Jikumaru
Yusuke
Y
Tatematsu
Kiyoshi
K
Pichon
Olivier
O
Renou
Jean-Pierre
JP
Kamiya
Yuji
Y
Nambara
Eiji
E
Truong
Hoai-Nam
HN
D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018525:Germination; D009154:Mutation; D009566:Nitrates / Q000378:metabolism* / Q000494:pharmacology; D010940:Plant Proteins; D018749:RNA, Plant / Q000187:drug effects / Q000235:genetics; D012639:Seeds / Q000187:drug effects / Q000502:physiology*; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D009566:Nitrates; D010940:Plant Proteins; D018749:RNA, Plant; D000040:Abscisic Acid; D003577:Cytochrome P-450 Enzyme System; C107203:abscisic acid 8'-hydroxylase