Responses of Primary Metabolites and Glucosinolates in Sulfur Deficient-Cabbage (Brassica rapa L. ssp. Pekinensis)

Abstract

Sulfur (S) is an essential mineral nutrient for plant growth and development and is a key component of many biological compounds. As S acquisition and assimilation have important roles in plant metabolism, S-deficient responses are closely involved in different plant constituents. In this study, we examined the effects of S deficiency on primary metabolism and glucosinolate (GSL) content in cabbage (Brassica rapa) plants. Soluble sugars such as glucose, fructose, galactose, and xylose, were up to 0.19-fold lower under S deficiency, and these changes were more pronounced with long-term (15 d) S deficiency. Significant increases in amino acids were observed in terms of glutamine (6.35-fold), glycine (20.54), serine (3.56), threonine (3.25), phenylalanine (4.07), β-alanine (7.88), and proline (4.58). S deficiency led to large accumulation of an indolyl GSL, 4-methoxyglucobrassicin, in both shoots (2.68 fold) and roots (5.99 fold). GSLs were positively correlated with the majority of primary metabolites in the shoots, but negative in the roots. Thus, at least in cabbage plants, the interplay between primary metabolism and GSLs appeared to be tissue-dependent, and the metabolic interaction between both metabolites should be elucidated.

Coordinating Sulfur Pools under Sulfate Deprivation

“…Milder reductions in other S-containing metabolites, including GSH, Met, Cys, SAM, SMM, and S-adenosyl-L-homocysteine (SAH) were also observed [15]. Conversely, OAS dramatically accumulated by up to 140-fold in roots on −S [15,17,37,42]. The levels of non-polar amino acids, including valine (Val), Isoleucine (Ile), leucine (Leu), phenylalanine (Phe), and tryptophan (Trp), and the polar amino acids serine (Ser), threonine (Thr), arginine (Arg), and glutamine (Gln) along with total free proteinogenic amino acids were increased in S-deprived roots [15].…”

“…High-throughput −S metabolomics studies were performed using different experimental setups investigating either the whole-seedling metabolome [11,22,35] or separated shoot and root metabolomes [15,17,37,42,43]. A common metabolic response of S-deprived shoots and roots is a decrease in S metabolites.…”

Sulfur Homeostasis in Plants

“…Many studies have been carried out on the response of plants to S nutrition at the physiological level [ 29 , 30 , 31 ]. Since S is a component of proteins, chloroplasts, and some important enzymes and coenzymes, S deficiency stress decreases S content and S-containing amino acids, leading to reduced metabolic activity in plants [ 29 , 30 , 31 ]. S deficiency leads to a hindrance of the synthesis of key enzymes in the process of carbon © metabolism, slows the rate of photosynthesis, and results in accumulation of more reactive oxygen species in plants [ 32 ].…”

Transcriptomic analysis at organ and time scale reveals gene regulatory networks controlling the sulfate starvation response of Solanum lycopersicum

“…Meta-analysis of transcriptomics data has shown that sulfate deficiencyresponsive genes are enriched in biological processes related to sulfate transport and metabolism, but also in processes related to cell wall organization, regulation of proteolysis, and metabolism of carbon and nitrogen [43]. The sulfate deficiency response has also been explored by metabolomics and proteomics analyses in Arabidopsis and crops [10,17,32,35,[44][45][46][47][48][49][50][51][52]. Furthermore, systems biology approaches that integrate multi-omics data have been adopted to generate a holistic vision of the sulfatedeficiency response [31].…”