Sultr4;1 mutant seeds of Arabidopsis have an enhanced sulphate content and modified proteome suggesting metabolic adaptations to altered sulphate compartmentalization.
BACKGROUND
Sulphur is an essential macronutrient needed for the synthesis of many cellular components. Sulphur containing amino acids and stress response-related compounds, such as glutathione, are derived from reduction of root-absorbed sulphate. Sulphate distribution in cell compartments necessitates specific transport systems. The low-affinity sulphate transporters SULTR4;1 and SULTR4;2 have been localized to the vacuolar membrane, where they may facilitate sulphate efflux from the vacuole.


RESULTS
In the present study, we demonstrated that the Sultr4;1 gene is expressed in developing Arabidopsis seeds to a level over 10-fold higher than the Sultr4;2 gene. A characterization of dry mature seeds from a Sultr4;1 T-DNA mutant revealed a higher sulphate content, implying a function for this transporter in developing seeds. A fine dissection of the Sultr4;1 seed proteome identified 29 spots whose abundance varied compared to wild-type. Specific metabolic features characteristic of an adaptive response were revealed, such as an up-accumulation of various proteins involved in sugar metabolism and in detoxification processes.


CONCLUSIONS
This study revealed a role for SULTR4;1 in determining sulphate content of mature Arabidopsis seeds. Moreover, the adaptive response of sultr4;1 mutant seeds as revealed by proteomics suggests a function of SULTR4;1 in redox homeostasis, a mechanism that has to be tightly controlled during development of orthodox seeds.
Zuber
Hélène
H
UMR102 Genetics and Ecophysiology of Grain legumes, INRA, F-21000 Dijon, France. helene.zuber@dijon.inra.fr
Davidian
Jean-Claude
JC
Wirtz
Markus
M
Hell
Rüdiger
R
Belghazi
Maya
M
Thompson
Richard
R
Gallardo
Karine
K
D000222:Adaptation, Physiological; D027321:Anion Transport Proteins / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002451:Cell Compartmentation; D004269:DNA, Bacterial / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D035264:Flowers / Q000502:physiology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D009584:Nitrogen / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D020543:Proteome / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D020543:Proteome; D012333:RNA, Messenger; D013431:Sulfates; C550543:Sultr4;1 protein, Arabidopsis; C036483:T-DNA; D002244:Carbon; D005978:Glutathione; D009584:Nitrogen