Mutations in the Arabidopsis homolog of LST8/GβL, a partner of the target of Rapamycin kinase, impair plant growth, flowering, and metabolic adaptation to long days.
The conserved Target of Rapamycin (TOR) kinase forms high molecular mass complexes and is a major regulator of cellular adaptations to environmental cues. The Lethal with Sec Thirteen 8/G protein β subunit-like (LST8/GβL) protein is a member of the TOR complexes, and two putative LST8 genes are present in Arabidopsis thaliana, of which only one (LST8-1) is significantly expressed. The Arabidopsis LST8-1 protein is able to complement yeast lst8 mutations and interacts with the TOR kinase. Mutations in the LST8-1 gene resulted in reduced vegetative growth and apical dominance with abnormal development of flowers. Mutant plants were also highly sensitive to long days and accumulated, like TOR RNA interference lines, higher amounts of starch and amino acids, including proline and glutamine, while showing reduced concentrations of inositol and raffinose. Accordingly, transcriptomic and enzymatic analyses revealed a higher expression of genes involved in nitrate assimilation when lst8-1 mutants were shifted to long days. The transcriptome of lst8-1 mutants in long days was found to share similarities with that of a myo-inositol 1 phosphate synthase mutant that is also sensitive to the extension of the light period. It thus appears that the LST8-1 protein has an important role in regulating amino acid accumulation and the synthesis of myo-inositol and raffinose during plant adaptation to long days.
Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France.
Manon
M
Moreau
Marianne
M
Azzopardi
Gilles
G
Clément
Thomas
T
Dobrenel
Chloé
C
Marchive
Charlotte
C
Renne
Marie-Laure
ML
Martin-Magniette
Ludivine
L
Taconnat
Jean-Pierre
JP
Renou
Christophe
C
Robaglia
Christian
C
Meyer
D000064:Acclimatization / Q000235:genetics*; D000596:Amino Acids / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D055442:Metabolome; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017440:Photoperiod; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D034622:RNA Interference; D059467:Transcriptome
D000596:Amino Acids; D029681:Arabidopsis Proteins; D019869:Phosphatidylinositol 3-Kinases; C512171:TOR protein, Arabidopsis