Abstract
BackgroundSulphur 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.ResultsIn 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.ConclusionsThis 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.
Highlights
Sulphur is an essential macronutrient needed for the synthesis of many cellular components
The analysis was performed on isolated seeds [7 and 10 days after flowering (DAF) corresponding to embryogenesis and seed filling stages, respectively], on isolated siliques and for other tissues, all collected during the reproductive growth phase of plants grown under sulphur-sufficient conditions
This remarkable ability allows the orthodox seed, i.e., seed that can be stored in a state of low moisture content [54], to survive for several years in a desiccated state with metabolic activities at a standstill, until the environmental conditions become optimal for its germination
Summary
Sulphur is an essential macronutrient needed for the synthesis of many cellular components. Sulphur deficiency has become an increasing problem in crops of many countries, notably in Western Europe, leading to sulphur deficiency symptoms and resulting in decreased crop yields and quality parameters [1,2,3]. In this context, sulphur acquisition and metabolism in plants has become a major concern for research and crop improvement. Sulphur is an essential macronutrient required for plant growth. It is mainly acquired by the plant roots as inorganic sulphate and distributed within the tissues [4].
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