S-methylmethionine Research Articles

Elucidating the importance of the catabolic enzyme, methionine-gamma-lyase, in stresses during Arabidopsis seed development and germination.

The sulfur-containing essential amino acid, methionine, is a key metabolite in plant cells since it is used as a precursor for the synthesis of vital metabolites. The transcript level of methionine's catabolic enzyme, methionine γ-lyase (MGL), accumulates in the seeds to a high level compared to other organs. The aim of this study was to reveal the role of MGL during seed development and germination. Using [13C]S-methylmethionine (SMM), the mobile form of methionine that is used to feed flower stalks of wild-type (WT) plants, revealed that the contents of [13C]methionine in seeds were significantly reduced when the plants underwent heat and osmotic stresses. Moreover, the levels of [13C]isoleucine, a product of MGL, significantly increased. Also, using the MGL promoter and gene fused to the GUS reporter gene, it was demonstrated that the heat stress significantly increased the protein level in the seeds. Therefore, we can conclude that MGL became active under stresses apparently to produce isoleucine, which is used as an osmoprotectant and an energy source. Transgenic Arabidopsis thaliana RNAi seeds with targeted repression of AtMGL during the late developmental stages of seeds show that the seeds did not accumulate methionine when they were grown under standard growth conditions, unlike the mgl-2, a knockout mutant, which showed a three-fold higher level of methionine. Also, when the RNAi plants developed under mid-heat stress, the level of methionine significantly increased while the content of isoleucine decreased compared to the control seeds, which strengthened the assumption that MGL is active under stress. The germination efficiency of the RNAi lines and mgl seeds were similar to their controls. However, the seeds that developed during heat or salt stress showed significantly lower germination efficiency compared to the control seeds. This implies that MGL is important to maintain the ability of the seeds to germinate. The RNAi lines and mgl seeds that developed under regular conditions, but germinated during salt or osmotic stress, exhibited a lower germination rate, suggesting an essential role of MGL also during this process. The results of this study show the important role of AtMGL in seeds under stresses.

Oxidative Brain Injury Induced by Amiodarone in Rats: Protective Effect of S-methyl Methionine Sulfonium Chloride.

Amiodarone (AMD) is a powerful antiarrhythmic drug preferred for treatments of tachycardias. Brain can be affected negatively when some drugs are used, including antiarrhythmics. S-methyl methionine sulfonium chloride (MMSC) is a well-known sulfur containing substance and a novel powerful antioxidant. It was intended to investigate the protective effects of MMSC on amiodarone induced brain damage. Rats were divided to four groups as follows, control (given corn oil), MMSC (50 mg/kg per day), AMD (100 mg/kg per day), AMD (100 mg/kg per day) + MMSC (50 mg/kg per day). The brain glutathione and total antioxidant levels, catalase, superoxide dismutase, glutathione peroxidase, paraoxonase, and Na+/K+-ATPase activities were decreased, lipid peroxidation and protein carbonyl, total oxidant status, oxidative stress index and reactive oxygen species levels, myeloperoxidase, acetylcholine esterase and lactate dehydrogenase activities were increased after AMD treatment. Administration of MMSC reversed these results. We can conclude that MMSC ameliorated AMD induced brain injury probably due to its antioxidant and cell protective effect.

Production of S-methyl-methionine using engineered Saccharomyces cerevisiae sake K6.

Introducing a plant-derived MMT gene encoding methionine S-methyltransferase into engineered Saccharomyces cerevisiae sake K6 allowed microbial production of S-methyl-methionine (SMM).

S-Methylmethionine Effectively Alleviates Stress in Szarvasi-1 Energy Grass by Reducing Root-to-Shoot Cadmium Translocation.

S-methylmethionine (SMM) is a universal metabolite of higher plants derived from L-methionine that has an approved priming effect under different types of abiotic and biotic stresses. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1) is a biomass plant increasingly applied in phytoremediation to stabilize or extract heavy metals. In this study, Szarvasi-1 was grown in a nutrient solution. As a priming agent, SMM was applied in 0.02, 0.05 and 0.1 mM concentrations prior to 0.01 mM Cd addition. The growth and physiological parameters, as well as the accumulation pattern of Cd and essential mineral nutrients, were investigated. Cd exposure decreased the root and shoot growth, chlorophyll concentration, stomatal conductance, photosystem II function and increased the carotenoid content. Except for stomatal conductance, SMM priming had a positive effect on these parameters compared to Cd treatment without priming. In addition, it decreased the translocation and accumulation of Cd. Cd treatment decreased K, Mg, Mn, Zn and P in the roots, and K, S, Cu and Zn in the shoots compared to the untreated control. SMM priming changed the pattern of nutrient uptake, of which Fe showed characteristic accumulation in the roots in response to increasing SMM concentrations. We have concluded that SMM priming exerts a positive effect on Cd-stressed Szarvasi-1 plants, which retained their physiological performance and growth. This ameliorative effect is suggested to be based on, at least partly, the lower root-to-shoot Cd translocation by the upregulated Fe uptake and transport.

Formation of dimethyl sulfide from the decomposition of S-methylmethionine in tea (Camellia sinensis) during manufacturing process and infusion brewing

Dimethyl sulfide (DMS) is a typical odorant contributing a cooked corn-like odor to tea (Camellia sinensis). In the study, noticeable increases of DMS (>350%) occurred in green, black, yellow, and white tea during brewing. Thermal model and quantitative analysis of S-methylmethionine (SMM) confirmed the thermal decomposition of SMM into DMS (44–80%) in tea infusion. The quantitative analysis on green and black tea manufacturing processes demonstrated thermal decomposition of SMM (12% and 9.0%, respectively) leads to DMS formation during the drying step. Besides, DMS was firstly suggested to be biosynthesed from yet unknown precursors due to high concentrations in fresh leaves (180 and 1700 μg/kg) and increases during rolling (190 and 2800 μg/kg) and fermentation (6400 μg/kg in black tea). The findings provided new insight of DMS formation from the decomposition of SMM in tea during manufacturing process and infusion brewing, which also help exploring its biosynthetic pathway during tea production.

The Protective Effects of S-Methyl Methionine Sulfonium Chloride on Brain Tissue Damage in D-Galactosamine-Induced Hepatotoxicity

Objective: The objective of the current work is to examine the protective effects of S-methyl methionine sulfonium chloride (MMSC) on brain in galactosamine (GalN)-induced hepatotoxicity in rats. Materials and Methods: A total of twenty two female Sprague-Dawley rats were randomly assigned into four groups as follows: Group I (n=5), intact control animals; Group II (n=6), animals that received 50 mg/kg/day of MMSC by gavage technique for 3 consecutive days; Group III (n=5), animals injected with a single dose of 500 mg/kg of GalN intraperitoneally (i.p.); and Group IV (n=6) are animals injected with the same dose of GalN (i.p.) 1 hour after MMSC treatment. At the end of the experiments (after 6 hours of the last GalN treatment), all animals were sacrificed under anaesthesia, and brain tissues were dissected out. Results: A statistically remarkable increase in lipid peroxidation, hydroxyproline, and nitric oxide levels, was detected while a notable decline in the activities of sodium/potassium ATPase was observed in GalN group in comparison with control rats. In contrast, all alterations observed were reversed when MMSC was given to GalN groups. Conclusion: Consequently, it may be considered that MMSC has a protective role on brain in GalN-induced hepatotoxicity in rats.

Physiological and Molecular Background of Maize Cold-Tolerance Enhancement with S-methylmethionine Salicylate

Low temperature is amongst the most influential abiotic stress factors, having deep impact on plant growth, yield and productivity. Studies on beneficial effects of certain biologically active substances, S-methylmethionine (SMM) and salicylic acid (SA) have provided a lot of valuable information regarding their role to counteract harmful effects of environmental stresses such as chilling. To obtain a more complex and stable defence compound with an extended range of stress-protective effect, the new derivative S-methylmethionine salicylate (MMS) was synthesised from the natural, biologically active substances SMM and SA. Since both original materials have complex stress-protective roles, the new compound was expected to combine the effects of original substances and to stabilise the unstable SMM in the new compound, thus providing an extended stress tolerance. Photosynthetic efficiency and accumulation of stress-related metabolites (polyamines and flavonoids) were measured in chilled and control plants, with and without MMS pretreatment, and expression changes of several genes involved in the cold stress response were analysed by quantitative real-time PCR (RT-qPCR) and a detailed microarray study. Our data show how the MMS combines the effect of SMM and SA on molecular level, causing numerous changes in the gene expression pattern and metabolite content. MMS gives rise to a better physiological condition, thus it could provide an alternative, environmental friendly way to enhance the plants defence mechanisms against stressors. As MMS is more stable than SMM, it promises easier, more long-lasting and more cost-effective usage in agriculture, with a complementing effect of SA.

Oxidative brain and cerebellum injury induced by d-galactosamine: Protective effect of S-methyl methionine sulfonium chloride.

The objective of this study was to examine the protective effects of S-methyl methionine sulfonium chloride (MMSC) against galactosamine (GalN)-induced brain and cerebellum injury in rats. A total of 22 female Sprague-Dawley rats were randomly divided into four groups as follows: Group I (n = 5), intact animals; Group II (n = 6), animals received 50 mg/kg/day of MMSC by gavage technique for 3 consecutive days; Group III (n = 5), animals injected with a single dose of 500 mg/kg of GalN intraperitoneally (ip); and Group IV (n = 6), animals injected with the same dose of GalN 1 h after MMSC treatment. After 6 h of the last GalN treatment (at the end of the experiments), all animals were killed under anesthesia, brain and cerebellum tissues were dissected out. Reduced glutathione, total antioxidant status levels, and antioxidant enzymes (catalase, superoxide dismutase, and glutathione-related enzymes), aryl esterase, and carbonic anhydrase activities remarkably declined whereas advanced oxidized protein products, reactive oxygen species, total oxidant status, oxidative stress index levels, and myeloperoxidase, acetylcholinesterase, lactate dehydrogenase, and xanthine oxidase activities were significantly elevated in the GalN group compared with intact rats. In contrast, the administration of MMSC to GalN groups reversed these alterations. In conclusion, we may suggest that MMSC has protective effects against GalN-induced brain and cerebellar toxicity in rats.

Genetic bases for the metabolism of the DMS precursor S-methylmethionine by Saccharomyces cerevisiae

Dimethyl sulfide (DMS) is a sulfur containing volatile that enhances general fruity aroma and imparts aromatic notes in wine. The most important precursor of DMS is S-methylmethionine (SMM), which is synthesized by grapes and can be metabolized by the yeast S. cerevisiae during wine fermentation. Precursor molecules left after fermentation are chemically converted to DMS during wine maturation, meaning that wine DMS levels are determined by the amount of remaining precursors at bottling.To elucidate SMM metabolism in yeast we performed quantitative trait locus (QTL) mapping using a population of 130 F2-segregants obtained from a cross between two wine yeast strains, and we detected one major QTL explaining almost 30% of trait variation. Within the QTL, gene YLL058W and SMM transporter gene MMP1 were found to influence SMM metabolism, from which MMP1 has the bigger impact. We identified and characterized a variant coding for a truncated transporter with superior SMM preserving attributes. A population analysis with 85 yeast strains from different origins revealed a significant association of the variant to flor strains and minor occurrence in cheese and wine strains.These results will help selecting and improving S. cerevisiae strains for the production of wine and other fermented foods containing DMS such as cheese or beer.

Antitumor and Antioxidant Activity of S-Methyl Methionine Sulfonium Chloride against Liver Cancer Induced in Wistar Albino Rats by Diethyl Nitrosamine and Carbon Tertrachloride

Liver disease, especially liver cancer, has become a threat facing the world. Now, antioxidant products are garnering great attention for the treatment and prevention of many diseases. S-Methyl methionine sulfonium chloride (MMSC) is a methionine derivative and is present in many vegetables and has anti-inflammatory effects and antioxidants. This is the first study aiming to investigate the antitumor activity of the MMSC. This study was carried out on 60 male Wistar albino rats (4–6 weeks old age) and divided into four groups, with the first group as normal control, second group as hepatocarcinoma induced by diethyl nitrosamine and carbon tetrachloride (DEN/CCL4) group, third group as normal rats treated with MMSC, and fourth group as hepatocellular carcinoma (HCC) induced rats treated with MMSC. Our findings revealed that MMSC administration after HCC induction significantly improved (p < 0.05) the liver function biomarkers, including AST, GGT, albumin, globulin, and albumin/globulin ratio (A/G), in comparison with those in the HCC group. Moreover, the histopathological changes of the liver tissue in the HCC group were improved by MMSC treatment. Likewise, the expression levels of tumor necrosis factor-alpha (TNF-α), induced nitric oxide synthase (iNOS), transforming growth factor (TGF-1β), and glypican 3 (GP3) were downregulated by MMSC treatment after HCC induction in comparison with those in the HCC-induced group. In conclusion, MMSC showed antitumor activity against HCC induction by DEN/CCl4 through decreasing lipid peroxide formation, the expression level of an inflammatory cytokines such as (TNF-α), immunoregulatory cytokines such as (TGF-1β), induced nitric oxide synthase, and glypican 3.

Identification of volatile sulfur-containing compounds and the precursor of dimethyl sulfide in cold-pressed rapeseed oil by GC–SCD and UPLC–MS/MS

Volatile sulfur-containing compounds (VSCs) provide an important contribution to foods due to their special odors. In this study, VSCs in 21 cold-pressed rapeseed oils (CROs) from 9 regions in China were extracted and separated by headspace solid-phase microextraction combined with gas chromatography coupled with sulfur chemiluminescence detection. 19 VSCs were identified by authentic standards, and the total concentration of VSCs in all CROs ranged from 49.0 to 18129 μg/kg. Dimethyl sulfide (DMS), with its high odor activity value (7–14574), was the most significant aroma contributor to the CROs. Furthermore, S-methylmethionine (SMM) in rapeseed was first affirmed by ultra-performance liquid chromatography–tandem mass spectrometry and isotope quantitation. The positive correlation coefficient between DMS and SMM was 0.793 (p < 0.05), which confirmed SMM as a crucial precursor of DMS in CROs. This study provided a theoretical basis for selecting rapeseed materials by the distribution of essential VSCs and the source of DMS.

English

Canola is a moderately salt tolerant plant, high salinity inhibits germination of seeds, vegetative growth of young plantlets, and reduces biomass production. This study investigated the effects of priming with 1 mM S-methylmethionine (SMM) on germination, leaf gas exchange, induced chlorophyll fluorescence, photosynthetic pigment content and membrane damage through lipid peroxidation by exposing canola (Brassica napus L. cv. Cindi) plants to moderate and severe salt stress (induced by 60 mM and 120 mM NaCl) for different periods. Priming with SMM alleviated the reduction of net photosynthetic rate, the effective quantum efficiency and efficiency of excitation energy capture by open photosystem II reaction centers, chlorophylls to carotenoids ratio, enhanced water use efficiency and contributed to reduction of oxidative membrane damage in fully developed young leaves. Delay and inhibition of seed germination by salt stress were significantly reduced by SMM, as well as the non-photochemical quenching of the singlet excited state of chlorophyll a, suggesting a more efficient protection against hyperosmotic stress, ionic toxicity and associated oxidative stress in primed plants exposed to high salinity. This first assay of SMM as a priming agent for canola plants under high salinity contributes to a better understanding of the mode of action of this natural, plant-derived bioactive compound and the optimization of canola cultivation under the adverse growth conditions caused by salt stress. © 2021 Friends Science Publishers

Isolation and identification of putative precursors of the volatile sulfur compounds and their inhibition methods in heat-sterilized melon juices

Volatile sulfur compounds, such as dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide, cause the off-flavor in heat-sterilized juices and limit the commercial production of juices. In this study, we investigated the precursors for these volatile sulfur compounds and analyzed the potential inhibition methods. Upon separation of melon juice components using resin column, the dimethyl sulfide precursor was present in the acidic fraction whereas the dimethyl trisulfide precursor was present in neutral and acidic fractions. Exogenous addition experiments indicated S-methyl methionine was the precursor of dimethyl sulfide, and methionine was the precursor of dimethyl disulfide and dimethyl trisulfide. The release of volatile sulfur compounds was reduced by decreasing the pH to 2.0, or by adding epicatechin. We concluded S-methyl methionine and methionine were degraded into volatile sulfur compounds through nucleophilic substitution and Strecker degradation. This study can help establishing protocols for controlling the release of volatile sulfur compounds in heat-sterilized juices.

Identification of key odorants responsible for cooked corn-like aroma of green teas made by tea cultivar ‘Zhonghuang 1′

Fangping green tea (FPGT) produced by Zhonghuang 1 (C. sinensis var. sinensis cv. Zhonghuang 1), a new tea variety, has a classical cooked corn-like aroma, which is completely different from the green tea aroma. In order to illustrate the aroma characteristics of the green tea, the volatiles of FPGT was analyzed with gas chromatography-mass spectrometry (GC-MS) and gas chromatography–olfactometry (GC-O). The results showed that odor activity value (OAV) of dimethyl sulfide (DMS) was 1195.21 and the odor intensity about DMS was 6.2 in FPGT. Aroma recombination experiment also confirmed the important contribution of DMS to cooked corn-like aroma. Aroma character impact (ACI) values of DMS in tea processed by Zhonghuang 1 and Fudingdabai were 72.01% and 37.86%, respectively. This indicated that the high proportion of DMS was the dominant character of green tea with cooked corn-like aroma. In addition, the S-methylmethionine (SMM) content in fresh leaves of Zhonghuang 1 (0.21 mg/g) was significantly higher than that of Fudingdabai (0.16 mg/g), which was an important reason for high DMS content.

Molecular evolution and expression divergence of three key Met biosynthetic genes in plants: CGS, HMT and MMT.

Methionine (Met) is an essential sulfur-containing amino acid in animals. Cereal and legume crops with limiting levels of Met represent the major food and feed sources for animals. In plants, cystathionine gamma-synthase (CGS), methionine methyltransferase (MMT) and homocysteine methyltransferase (HMT) are committing enzymes synergistically synthesizing Met through the aspartate (Asp) family pathway and the S-methylmethionine (SMM) cycle. The biological functions of CGS, MMT and HMT genes have been respectively studied, whereas their evolution patterns and their contribution to the evolution of Met biosynthetic pathway in plants are unknown. In the present study, to reveal their evolution patterns and contribution, the evolutionary relationship of CGS, MMT and HMT gene families were reconstructed. The results showed that MMTs began in the ancestor of the land plants and kept conserved during evolution, while the CGSs and HMTs had diverged. The CGS genes were divided into two branches in the angiosperms, Class 1 and Class 2, of which Class 2 only contained the grasses. However, the HMT genes diverged into Class 1 and Class 2 in all of the seed plants. Further, the gene structure analysis revealed that the CGSs, MMTs and HMTs were relatively conserved except for the CGSs in Class 2. According to the expression of CGS, HMT and MMT genes in soybeans, as well as in the database of soybean, rice and Arabidopsis, the expression patterns of the MMTs were shown to be consistently higher in leaves than in seeds. However, the expression of CGSs and HMTs had diverged, either expressed higher in leaves or seeds, or showing fluctuated expression. Additionally, the functions of HMT genes had diverged into the repair of S-adenosylmethionine and SMM catabolism during the evolution. The results indicated that the CGS and HMT genes have experienced partial subfunctionalization. Finally, given the evolution and expression of the CGS, HMT and MMT gene families, we built the evolutionary model of the Met biosynthetic pathways in plants. The model proposed that the Asp family pathway existed in all the plant lineages, while the SMM cycle began in the ancestor of land plants and then began to diverge in the ancestor of seed plants. The model suggested that the evolution of Met biosynthetic pathway is basically consistent with that of plants, which might be vital to the growth and development of different botanical lineages during evolution.

Identification of Cooked Off-Flavor Components and Analysis of Their Formation Mechanisms in Melon Juice during Thermal Processing.

Cooked off-flavor components were identified, and their formation mechanisms were studied in heat-treated melon juices. When flavor dilution analysis methods and odor activity values were used to evaluate the cooked off-flavor in heat-treated melon juice, four volatile sulfide compounds (VSCs) were identified as contributors to the cooked off-flavor: dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), dimethyl sulfide (DMS), and 3-(methylthio)propanal (MTP). The cooked off-flavor intensities of heated juices from thick-skinned melons were stronger than those in juices from thin-skinned melons. We conducted a comparative analysis of VSCs before and after heat treatment by adding unlabeled and labeled S-methylmethionine (SMM) and/or methionine (Met) to the original melon juices. DMS and MTP were formed from SMM and Met through nucleophilic substitution and Strecker degradation, respectively. DMDS and DMTS were partly formed through the oxidative degradation of methanethiol produced from Met. Moreover, SMM could accelerate degradation of Met by increasing the amount of dicarbonyl compounds during heat treatment.

Molecular Evolution and Expression Divergence of HMT Gene Family in Plants.

Homocysteine methyltransferase (HMT) converts homocysteine to methionine using S-methylmethionine (SMM) or S-adenosylmethionine (SAM) as methyl donors in organisms, playing an important role in supplying methionine for the growth and the development of plants. To better understand the functions of the HMT genes in plants, we conducted a wide evolution and expression analysis of these genes. Reconstruction of the phylogenetic relationship showed that the HMT gene family was divided into Class 1 and Class 2. In Class 1, HMTs were only found in seed plants, while Class 2 presented in all land plants, which hinted that the HMT genes might have diverged in seed plants. The analysis of gene structures and selection pressures showed that they were relatively conserved during evolution. However, type I functional divergence had been detected in the HMTs. Furthermore, the expression profiles of HMTs showed their distinct expression patterns in different tissues, in which some HMTs were widely expressed in various organs, whereas the others were highly expressed in some specific organs, such as seeds or leaves. Therefore, according to our results in the evolution, functional divergence, and expression, the HMT genes might have diverged during evolution. Further analysis in the expression patterns of AthHMTs with their methyl donors suggested that the diverged HMTs might be related to supply methionine for the development of plant seeds.

Impact of Gaseous Carbon Dioxide and Boiling Power on Dimethyl Sulfide Stripping Behavior during Wort Boiling

The impact of carbon dioxide (CO2) supply flow rate on dimethyl sulfide (DMS) removal during wort boiling was studied when applying a 1 h hold between the end of preheating and the beginning of boiling. This was done during wort boiling by varying the boiling power (from 500 to 1,500 W), aiming to reduce energy consumption to reach the target of an end-of-boil DMS concentration of 100 ppb (w/v). When using the Mitani equation, which describes S-methyl methionine (SMM) conversion into DMS and DMS stripping, the preboiling step allowed a reaction rate coefficient of SMM conversion (k1) value of 0.0099 min−1 to be obtained. The values of volatilization rate coefficient of DMS (k2) during the provision of CO2 at a flow rate between 5 and 11 L/min and boiling power between 500 and 1,500 W were between 0.02049 and 0.07882 min−1. It was found that the coefficient k2 increased with the increase of CO2 supply flow rate and the increase of boiling power. At a fixed boiling power of 1,500 W, the use of CO2 supply flow rate permitted the target of 100 ppb to be attained in an interval of 39.21 min for 11 L/min to 62.31 min for 5 L/min. The energy saved in the boiling process when applying CO2 supply flow rate between 5 and 11 L/min was 2.49–4.57 MJ.

Modeling of Dimethyl Sulfide Stripping Behavior When Applying Delayed Onset of Boiling during Wort Boiling

The response surface methodology, using the central composite design as a tool for modeling, was used to study the impact of two parameters (power supply and boiling time) and their effect on dimethyl sulfide (DMS) removal during wort boiling, when applying delayed onset of boiling. It was observed that the two parameters were significantly impacting the DMS removal with a 21% contribution for power supply and a 58% contribution for the boiling time (P = 0.000 for both). The interaction of the two factors was also significant (P = 0.008) with a contribution of 7%. With the S-methyl methionine conversion to DMS following the pseudo first-order kinetics reaction, k1 was computed as 0.0054 min−1, and the values of k2 were between 0.0151 and 0.407 min−1. After several statistical analyses, we learned that the results coming from the theoretical equations for DMS removal at each studied power supply were not significantly different from the experimental value obtained in the laboratory, validated by the use of these equations. The time spent to reach the residual DMS target of 30, 50, and 100 ppb was 141–377, 94–295, and 60–197 min, respectively, and the energy used to reach the same target was 11.31–12.69, 8.46–8.85, and 5.40–5.91 MJ, respectively.

Repression of CYSTATHIONINE γ-SYNTHASE in Seeds Recruits the S-Methylmethionine Cycle.

S-Methylmethionine (SMM) was suggested previously to participate in the metabolism of methionine (Met) in seeds. To further reveal its roles, we had previously produced transgenic Arabidopsis (Arabidopsis thaliana) RNA interference (RNAi) seeds with lower transcript expression of CYSTATHIONINE γ-SYNTHASE (AtCGS), Met's main regulatory enzyme. Unexpectedly, these seeds accumulated significantly higher levels of Met compared with control seeds through an as yet unknown mechanism. Here, transcript and metabolic analyses coupled with isotope-labeled [13C]SMM and [13C]Met feeding experiments enabled us to reveal that SMM that was synthesized in rosette leaves of RNAi plants significantly contributed to the accumulation of Met in their seeds at late stages of development. Seed-specific repression of AtCGS in RNAi seeds triggered the induction of genes operating in the SMM cycle of rosette leaves, leading to elevated transport of SMM toward the seeds, where higher reconversion rates of SMM to Met were detected. The metabolic rearrangements in RNAi seeds resulted in an altered sulfur-associated metabolism, such as lower amounts of Cys and glutathione, as well as a differential composition of glucosinolates. Together, the data propose a novel cross talk existing between seeds and rosette leaves along with mutual effects between the Asp family and SMM pathways operating in these tissues. They also shed light on the effects of higher Met levels on seed physiology and behavior.