The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Rachel Amir - One of the best experts on this subject based on the ideXlab platform.
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Repression of CYSTATHIONINE γ-SYNTHASE in Seeds Recruits the S-Methylmethionine Cycle
Plant Physiology, 2017Co-Authors: Hagai Cohen, Yael Hacham, Irina Panizel, Ilana Rogachev, Asaph Aharoni, Rachel AmirAbstract: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.
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The relative contribution of genes operating in the S-Methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds . Abstract Methionine, a sulfur-containing amino acid, is a key metabolite in plant cells. The previous lines of evidence proposed that the S -methylmethionine (SMM) cycle contributes to methionine synthesis in seeds where methionine that is produced in non-seed tissues is converted to SMM and then transported via the phloem into the seeds. However, the relative regulatory roles of the S -methyltransferases operating within this cycle in seeds are yet to be fully understood. In the current study, we generated transgenic Arabidopsis seeds with altered expression of three HOMOCYSTEINE S -METHYLTRANSFERASEs (HMTs) and METHIONINE S -METHYLTRANSFERASE (MMT), and profiled them for transcript and metabolic changes. The results revealed that AtHMT1 and AtHMT3, but not AtHMT2 and AtMMT, are the predominant enzymes operating in seeds as altered expression of these two genes affected the levels of methionine and SMM in transgenic seeds. Their manipulations resulted in adapted expression level of genes participating in methionine synthesis through the SMM and aspartate family pathways. Taken together, our findings provide new insights into the regulatory roles of the SMM cycle and the mutual effects existing between the two methionine biosynthesis pathways, highlighting the complexity of the metabolism of methionine and SMM in seeds.
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The relative contribution of genes operating in the S -methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds.
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Methionine and S-Methylmethionine exhibit temporal and spatial accumulation patterns during the Arabidopsis life cycle
Amino Acids, 2015Co-Authors: Alon Frank, Hagai Cohen, Dotan Hoffman, Rachel AmirAbstract:Methionine is a nutritionally essential sulfur-containing amino acid found at low levels in plant tissues. Yet, the factors that regulate its synthesis and accumulation in seeds are not fully known. Recent genetic studies demonstrate that Arabidopsis seeds are able to synthesize methionine de novo through the aspartate family pathway similarly to vegetative tissues; however, additional biochemical studies suggest that the S -methylmethionine (SMM) cycle also plays a major role in methionine synthesis in seeds. To better understand the contribution of these two pathways to methionine synthesis, we have sampled various vegetative and reproductive tissues during the Arabidopsis life cycle and determined the contents of soluble and protein-incorporated methionine, SMM, as well as the expression levels of the key genes involved in these two pathways. Our results strengthen the hypothesis that SMM that is produced in the rosette leaves from methionine contributes to methionine accumulation in seeds. However, the SMM cycle may have additional functions in plant tissues since its key genes were expressed in all of the examined tissues, although at different rates. The accumulation patterns of soluble and protein-incorporated methionine during the Arabidopsis life cycle were found to be similar to most of the other amino acids, especially to those belonging to the branched-chain and aromatic amino acids that are produced in chloroplasts together with methionine. This indicates that similar factors regulate the levels of amino acids during development.
Hagai Cohen - One of the best experts on this subject based on the ideXlab platform.
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Repression of CYSTATHIONINE γ-SYNTHASE in Seeds Recruits the S-Methylmethionine Cycle
Plant Physiology, 2017Co-Authors: Hagai Cohen, Yael Hacham, Irina Panizel, Ilana Rogachev, Asaph Aharoni, Rachel AmirAbstract: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.
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The relative contribution of genes operating in the S-Methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds . Abstract Methionine, a sulfur-containing amino acid, is a key metabolite in plant cells. The previous lines of evidence proposed that the S -methylmethionine (SMM) cycle contributes to methionine synthesis in seeds where methionine that is produced in non-seed tissues is converted to SMM and then transported via the phloem into the seeds. However, the relative regulatory roles of the S -methyltransferases operating within this cycle in seeds are yet to be fully understood. In the current study, we generated transgenic Arabidopsis seeds with altered expression of three HOMOCYSTEINE S -METHYLTRANSFERASEs (HMTs) and METHIONINE S -METHYLTRANSFERASE (MMT), and profiled them for transcript and metabolic changes. The results revealed that AtHMT1 and AtHMT3, but not AtHMT2 and AtMMT, are the predominant enzymes operating in seeds as altered expression of these two genes affected the levels of methionine and SMM in transgenic seeds. Their manipulations resulted in adapted expression level of genes participating in methionine synthesis through the SMM and aspartate family pathways. Taken together, our findings provide new insights into the regulatory roles of the SMM cycle and the mutual effects existing between the two methionine biosynthesis pathways, highlighting the complexity of the metabolism of methionine and SMM in seeds.
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The relative contribution of genes operating in the S -methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds.
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Methionine and S-Methylmethionine exhibit temporal and spatial accumulation patterns during the Arabidopsis life cycle
Amino Acids, 2015Co-Authors: Alon Frank, Hagai Cohen, Dotan Hoffman, Rachel AmirAbstract:Methionine is a nutritionally essential sulfur-containing amino acid found at low levels in plant tissues. Yet, the factors that regulate its synthesis and accumulation in seeds are not fully known. Recent genetic studies demonstrate that Arabidopsis seeds are able to synthesize methionine de novo through the aspartate family pathway similarly to vegetative tissues; however, additional biochemical studies suggest that the S -methylmethionine (SMM) cycle also plays a major role in methionine synthesis in seeds. To better understand the contribution of these two pathways to methionine synthesis, we have sampled various vegetative and reproductive tissues during the Arabidopsis life cycle and determined the contents of soluble and protein-incorporated methionine, SMM, as well as the expression levels of the key genes involved in these two pathways. Our results strengthen the hypothesis that SMM that is produced in the rosette leaves from methionine contributes to methionine accumulation in seeds. However, the SMM cycle may have additional functions in plant tissues since its key genes were expressed in all of the examined tissues, although at different rates. The accumulation patterns of soluble and protein-incorporated methionine during the Arabidopsis life cycle were found to be similar to most of the other amino acids, especially to those belonging to the branched-chain and aromatic amino acids that are produced in chloroplasts together with methionine. This indicates that similar factors regulate the levels of amino acids during development.
Ilona Rácz - One of the best experts on this subject based on the ideXlab platform.
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The newly synthesized plant growth regulator S-Methylmethionine salicylate may provide protection against high salinity in wheat
Plant Growth Regulation, 2018Co-Authors: Tibor Janda, Radwan Khalil, Judit Tajti, Gabriella Szalai, Szabolcs Rudnóy, Ilona Rácz, György Kátay, Anna B. Molnár, Magdalena A. Lejmel, Tihana MarčekAbstract:High salinity is one of the major environmental factors limiting the productivity of crop species worldwide. Improving the stress tolerance of cultivated plants and thus increasing crop yields in an environmentally friendly way is a crucial task in agriculture. In the present work the ability of a new derivative, S -methylmethionine-salicylate (MMS), to improve the salt tolerance of wheat plants was tested parallel with its related compounds salicylic acid and S -methylmethionine. The results show that while these compounds are harmful at relatively high concentration (0.5 mM), they may provide protection against high salinity at lower (0.1 mM) concentration. This was confirmed by gas exchange, chlorophyll content and chlorophyll- a fluorescence induction measurements. While osmotic adjustment probably plays a critical role in the improved salt tolerance, neither Na or K transport from the roots to the shoots nor proline synthesis are the main factors in the tolerance induced by the compounds tested. MMS, S -methylmethionine and Na-salicylate had different effects on flavonol biosynthesis. It was also shown that salt treatment had a substantial influence on the SA metabolism in wheat roots and leaves. Present results suggest that the investigated compounds can be used to improve salt tolerance in plants.
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Protective role of S-Methylmethionine-salicylate in maize plants infected with Maize dwarf mosaic virus
European Journal of Plant Pathology, 2017Co-Authors: Edit Ludmerszki, Ilona Rácz, György Kátay, Asztéria Almási, Ádám Solti, Csilla Oláh, Sengnirane Chounramany, Iván Bélai, Szabolcs RudnóyAbstract:This study aimed to detect the harmful effects of Maize dwarf mosaic virus (MDMV) infection, and to demonstrate the potential benefits of S-Methylmethionine-salicylate (MMS) pretreatment in infected maize ( Zea mays L.) plants. The results of chlorophyll a fluorescence measurements showed that in MDMV-infected plants additional quenchers of fluorescence appear, probably as the result of associations between the virus coat protein and thylakoid membranes. It is important to note that when infected plants were pretreated with MMS, such associations were not formed. MDMV infection and MMS pretreatment resulted in a decrease in ascorbate peroxidase (APX) activity in maize leaves, while infection contributed to an increase in activity in the roots. Infection raised the guaiacol peroxidase (GPX) enzyme activity level, which was reduced by MMS pretreatment. MMS contributed to a decrease in both the RNA and coat protein content of MDMV, to an equal extent in maize leaves and roots. The results showed that MMS pretreatment enhanced the stress response reactions against MDMV infection in maize plants and retarded the spreading of infection.
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S-Methylmethionine contributes to enhanced defense against Maize dwarf mosaic virus infection in maize
Brazilian Journal of Botany, 2015Co-Authors: Edit Ludmerszki, Ilona Rácz, Zoltán Szigeti, Asztéria Almási, Ádám Solti, Csilla Oláh, Szabolcs RudnóyAbstract:The beneficial and protective effects of S -methylmethionine (SMM) were investigated in Maize dwarf mosaic virus (MDMV) infected maize ( Zea mays L.). Response reactions and alterations in the physiological state of the plants were monitored by following changes in the values of chlorophyll a fluorescence and chlorophyll content, and differences in the expression patterns of the stress-related genes S - adenosylmethionine synthase ( SAMS ) and the 14-3-3-like protein gene G - box factor 14 - 6 (GF14 - 6 ). Infection was validated using the ELISA technique. A pronounced decrease in the red to far-red chlorophyll a fluorescence ratio, indicative of chlorophyll content, was observed in infected plants, which was tempered by SMM pretreatment. A noticeable decrease in the photochemical quenching of photosystem II and the thermal dissipation of the antennae was observed, together with a notable increase in other non-photochemical energy dissipation parameters in response to MDMV infection. SMM treatment enhanced blue fluorescence in both uninfected and MDMV-infected plants (probably due to the production of protective phenolic compounds), while infection characteristically increased green fluorescence emission. SMM treatment was found to elevate the rate of gene expressions of SAMS and GF14 - 6 . The results suggest that SMM pretreatment enhances the stress response reactions that protect maize plants against MDMV infection.
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Interactions of S-Methylmethionine and UV-B can modify the defence mechanisms induced in maize
Acta Physiologiae Plantarum, 2015Co-Authors: Szabolcs Rudnóy, Ilona Rácz, Imre Majláth, Katalin Páldi, Tibor JandaAbstract:We examined the interactions of an exogenously added non-proteinogenic amino acid, S -methylmethionine (SMM) and UV-B radiation in young maize plants. We observed that exposure to UV-B light caused a substantial increase in both the phenolics and anthocyanin contents. Pretreatment with SMM also induced a slight, but statistically significant increase in the total phenol content, and was also able to accelerate the rise in the UV-B-induced anthocyanin level. Gene expression patterns indicated that the general phenylpropanoid pathway was most strongly induced by the combined effect of SMM and UV, while the anthocyanin synthesis by the sole UV-B treatment. SMM treatment and UV-B light led to a substantial increase in the activities of the antioxidant enzymes catalase (CAT), ascorbate peroxidase (APX) and glutathione S -transferase and SMM pretreatment always enhanced the effect of UV-B. While the activity of CAT showed a significant increase in UV-B- and/or SMM-treated plants, APX was stimulated only by SMM. The present results suggest that the protective mechanisms induced by UV-B radiation could be enhanced by SMM treatment and reinforce the earlier observations of priming effects of SMM so that it can contribute to our knowledge about the SMM-induced protection against various types of stressors.
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S-Methylmethionine alleviates the cold stress by protection of the photosynthetic apparatus and stimulation of the phenylpropanoid pathway
Biologia Plantarum, 2013Co-Authors: K. Páldi, Zoltán Szigeti, Ilona Rácz, Szabolcs RudnóyAbstract:Maize (Zea mays L.) seedlings were pretreated with 0.001 g dm−3 S-Methylmethionine (SMM) in the nutrient solution for 24 h and then subjected to chilling (6 °C for 2, 4, 6, 10, and 24 h). Cold stress significantly decreased the maximum quantum yield of photosystem II (variable to maximum chlorophyll fluorescence ratio, Fv/Fm) during the whole experiment but SMM pretreatment significantly reduced this decline. Content of phenolics and anthocyanins increased in response to low temperature, and SMM pretreatment further intensified the synthesis of these protective agents. These findings were supported by increased expression of genes coding enzymes of the phenylpropanoid pathway leading to synthesis of cinnamate-4-hydroxylase (C4H) and chalcone-synthase (CHS). Our results indicate that SMM pretreatment alleviates the low temperature stress by reducing the damage of the photosynthetic apparatus and stimulating the phenylpropanoid pathway.
Yael Hacham - One of the best experts on this subject based on the ideXlab platform.
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Repression of CYSTATHIONINE γ-SYNTHASE in Seeds Recruits the S-Methylmethionine Cycle
Plant Physiology, 2017Co-Authors: Hagai Cohen, Yael Hacham, Irina Panizel, Ilana Rogachev, Asaph Aharoni, Rachel AmirAbstract: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.
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The relative contribution of genes operating in the S-Methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds . Abstract Methionine, a sulfur-containing amino acid, is a key metabolite in plant cells. The previous lines of evidence proposed that the S -methylmethionine (SMM) cycle contributes to methionine synthesis in seeds where methionine that is produced in non-seed tissues is converted to SMM and then transported via the phloem into the seeds. However, the relative regulatory roles of the S -methyltransferases operating within this cycle in seeds are yet to be fully understood. In the current study, we generated transgenic Arabidopsis seeds with altered expression of three HOMOCYSTEINE S -METHYLTRANSFERASEs (HMTs) and METHIONINE S -METHYLTRANSFERASE (MMT), and profiled them for transcript and metabolic changes. The results revealed that AtHMT1 and AtHMT3, but not AtHMT2 and AtMMT, are the predominant enzymes operating in seeds as altered expression of these two genes affected the levels of methionine and SMM in transgenic seeds. Their manipulations resulted in adapted expression level of genes participating in methionine synthesis through the SMM and aspartate family pathways. Taken together, our findings provide new insights into the regulatory roles of the SMM cycle and the mutual effects existing between the two methionine biosynthesis pathways, highlighting the complexity of the metabolism of methionine and SMM in seeds.
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The relative contribution of genes operating in the S -methylmethionine cycle to methionine metabolism in Arabidopsis seeds
Plant Cell Reports, 2017Co-Authors: Hagai Cohen, Asaf Salmon, Zipora Tietel, Yael Hacham, Rachel AmirAbstract:Key message Enzymes operating in the S -methylmethionine cycle make a differential contribution to methionine synthesis in seeds. In addition, mutual effects exist between the S -methylmethionine cycle and the aspartate family pathway in seeds.
Szabolcs Rudnóy - One of the best experts on this subject based on the ideXlab platform.
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The newly synthesized plant growth regulator S-Methylmethionine salicylate may provide protection against high salinity in wheat
Plant Growth Regulation, 2018Co-Authors: Tibor Janda, Radwan Khalil, Judit Tajti, Gabriella Szalai, Szabolcs Rudnóy, Ilona Rácz, György Kátay, Anna B. Molnár, Magdalena A. Lejmel, Tihana MarčekAbstract:High salinity is one of the major environmental factors limiting the productivity of crop species worldwide. Improving the stress tolerance of cultivated plants and thus increasing crop yields in an environmentally friendly way is a crucial task in agriculture. In the present work the ability of a new derivative, S -methylmethionine-salicylate (MMS), to improve the salt tolerance of wheat plants was tested parallel with its related compounds salicylic acid and S -methylmethionine. The results show that while these compounds are harmful at relatively high concentration (0.5 mM), they may provide protection against high salinity at lower (0.1 mM) concentration. This was confirmed by gas exchange, chlorophyll content and chlorophyll- a fluorescence induction measurements. While osmotic adjustment probably plays a critical role in the improved salt tolerance, neither Na or K transport from the roots to the shoots nor proline synthesis are the main factors in the tolerance induced by the compounds tested. MMS, S -methylmethionine and Na-salicylate had different effects on flavonol biosynthesis. It was also shown that salt treatment had a substantial influence on the SA metabolism in wheat roots and leaves. Present results suggest that the investigated compounds can be used to improve salt tolerance in plants.
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Protective role of S-Methylmethionine-salicylate in maize plants infected with Maize dwarf mosaic virus
European Journal of Plant Pathology, 2017Co-Authors: Edit Ludmerszki, Ilona Rácz, György Kátay, Asztéria Almási, Ádám Solti, Csilla Oláh, Sengnirane Chounramany, Iván Bélai, Szabolcs RudnóyAbstract:This study aimed to detect the harmful effects of Maize dwarf mosaic virus (MDMV) infection, and to demonstrate the potential benefits of S-Methylmethionine-salicylate (MMS) pretreatment in infected maize ( Zea mays L.) plants. The results of chlorophyll a fluorescence measurements showed that in MDMV-infected plants additional quenchers of fluorescence appear, probably as the result of associations between the virus coat protein and thylakoid membranes. It is important to note that when infected plants were pretreated with MMS, such associations were not formed. MDMV infection and MMS pretreatment resulted in a decrease in ascorbate peroxidase (APX) activity in maize leaves, while infection contributed to an increase in activity in the roots. Infection raised the guaiacol peroxidase (GPX) enzyme activity level, which was reduced by MMS pretreatment. MMS contributed to a decrease in both the RNA and coat protein content of MDMV, to an equal extent in maize leaves and roots. The results showed that MMS pretreatment enhanced the stress response reactions against MDMV infection in maize plants and retarded the spreading of infection.
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S-Methylmethionine contributes to enhanced defense against Maize dwarf mosaic virus infection in maize
Brazilian Journal of Botany, 2015Co-Authors: Edit Ludmerszki, Ilona Rácz, Zoltán Szigeti, Asztéria Almási, Ádám Solti, Csilla Oláh, Szabolcs RudnóyAbstract:The beneficial and protective effects of S -methylmethionine (SMM) were investigated in Maize dwarf mosaic virus (MDMV) infected maize ( Zea mays L.). Response reactions and alterations in the physiological state of the plants were monitored by following changes in the values of chlorophyll a fluorescence and chlorophyll content, and differences in the expression patterns of the stress-related genes S - adenosylmethionine synthase ( SAMS ) and the 14-3-3-like protein gene G - box factor 14 - 6 (GF14 - 6 ). Infection was validated using the ELISA technique. A pronounced decrease in the red to far-red chlorophyll a fluorescence ratio, indicative of chlorophyll content, was observed in infected plants, which was tempered by SMM pretreatment. A noticeable decrease in the photochemical quenching of photosystem II and the thermal dissipation of the antennae was observed, together with a notable increase in other non-photochemical energy dissipation parameters in response to MDMV infection. SMM treatment enhanced blue fluorescence in both uninfected and MDMV-infected plants (probably due to the production of protective phenolic compounds), while infection characteristically increased green fluorescence emission. SMM treatment was found to elevate the rate of gene expressions of SAMS and GF14 - 6 . The results suggest that SMM pretreatment enhances the stress response reactions that protect maize plants against MDMV infection.
-
Interactions of S-Methylmethionine and UV-B can modify the defence mechanisms induced in maize
Acta Physiologiae Plantarum, 2015Co-Authors: Szabolcs Rudnóy, Ilona Rácz, Imre Majláth, Katalin Páldi, Tibor JandaAbstract:We examined the interactions of an exogenously added non-proteinogenic amino acid, S -methylmethionine (SMM) and UV-B radiation in young maize plants. We observed that exposure to UV-B light caused a substantial increase in both the phenolics and anthocyanin contents. Pretreatment with SMM also induced a slight, but statistically significant increase in the total phenol content, and was also able to accelerate the rise in the UV-B-induced anthocyanin level. Gene expression patterns indicated that the general phenylpropanoid pathway was most strongly induced by the combined effect of SMM and UV, while the anthocyanin synthesis by the sole UV-B treatment. SMM treatment and UV-B light led to a substantial increase in the activities of the antioxidant enzymes catalase (CAT), ascorbate peroxidase (APX) and glutathione S -transferase and SMM pretreatment always enhanced the effect of UV-B. While the activity of CAT showed a significant increase in UV-B- and/or SMM-treated plants, APX was stimulated only by SMM. The present results suggest that the protective mechanisms induced by UV-B radiation could be enhanced by SMM treatment and reinforce the earlier observations of priming effects of SMM so that it can contribute to our knowledge about the SMM-induced protection against various types of stressors.
-
S-Methylmethionine alleviates the cold stress by protection of the photosynthetic apparatus and stimulation of the phenylpropanoid pathway
Biologia Plantarum, 2013Co-Authors: K. Páldi, Zoltán Szigeti, Ilona Rácz, Szabolcs RudnóyAbstract:Maize (Zea mays L.) seedlings were pretreated with 0.001 g dm−3 S-Methylmethionine (SMM) in the nutrient solution for 24 h and then subjected to chilling (6 °C for 2, 4, 6, 10, and 24 h). Cold stress significantly decreased the maximum quantum yield of photosystem II (variable to maximum chlorophyll fluorescence ratio, Fv/Fm) during the whole experiment but SMM pretreatment significantly reduced this decline. Content of phenolics and anthocyanins increased in response to low temperature, and SMM pretreatment further intensified the synthesis of these protective agents. These findings were supported by increased expression of genes coding enzymes of the phenylpropanoid pathway leading to synthesis of cinnamate-4-hydroxylase (C4H) and chalcone-synthase (CHS). Our results indicate that SMM pretreatment alleviates the low temperature stress by reducing the damage of the photosynthetic apparatus and stimulating the phenylpropanoid pathway.
