About this Research Topic
Growing plants have a constitutive demand for thiol (sulfur) to synthesize protein, sulfolipid and other essential sulfur (S) containing molecules for growth and development. The uptake and subsequent distribution of sulfate is regulated in response to demand and environmental cues. The acquisition of sulfur by plants has become an increasingly important concern for the agriculture due to the decreasing trends of S-emissions from industrial sources and the consequent limitation of inputs from deposition. The recognition of the importance of sulfate for plant growth and vigor and hence crop yield, as well as the nutritional quality for human and animal diets, has increasingly been recognized. Cysteine is the first committed molecule in plant metabolism that contains both sulfur and nitrogen, and, thus, the regulation of its biosynthesis is of utmost importance for the synthesis of a number of essential metabolites in plant metabolic pathways. Cysteine is incorporated into proteins and glutathione directly or serves as a sulfur donor for the synthesis of S-containing compounds such as methionine and its derivatives S-adenosylmethionine and S-methylmethionine, and many secondary compounds. Furthermore, cysteine acts as a general catalyst in redox reactions through the nucleophilic properties of its sulfur atom, utilizing dithiol-disulfide interchange, as displayed in the thioredoxin and the glutaredoxin systems. Molecular characterization involving transcriptomics, proteomics and metabolomics profiling in major crops like rice, barley, wheat, maize, and legumes along with model plant Arabidopsis thaliana revealed that sulfate uptake, distribution and reductive assimilation are regulated in fine tune depending on sulfur status and demand, and that this cascade somehow may be integrated with cell cycle, plant photosynthesis, nutrient transports, antioxidant defense system, hormonal signaling, kinase cascades, carbohydrate metabolism, and during plants’ experiences with different biotic and abiotic stresses. This cascade can be manipulated in favor of enhanced plant growth and nutritional benefits for major food crops around the world for which holistic understanding of thiol-metabolisms and its coordination with other vital cellular and metabolic events is necessary. Although considerable progress has been made regarding the central role of sulfur metabolisms in regulation of plant growth, development and stress response, several frontiers need to be explored to reveal the cross-talk between thiol-metabolisms and above said metabolic events. Knowledge on potential identity and roles of different thiol transporters between cell components/organelles are also not integrated and input is necessary from diverse taxa. This emerging prospect can be ushered by using latest cutting-edge functional genomics tools and better understanding of plant thiol metabolism from source (soil) to sink (grains) in different areas of ‘thiolomics’. In this research topic, I suggest a comprehensive knowledge generated in this area. Focus is put not only on molecular mechanisms of sulfur metabolisms but also on its integration/role/participation with other vital metabolic events such as carbon, sugar and nitrogen, cell division process, kinase cascades and hormone signaling. All types of articles (original research, method, opinion and review) that provide new insights into different aspects of thiol-metabolisms in plant growth, development and stress responses are welcome. I wish to trigger cross-talk within components of functional biology related to plant sulfur metabolisms so that the gathered knowledge of which can ultimately be utilized as a potential think-tank for future plant production.
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