Free Amino Acids and Methylglyoxal as Players in the Radiation Hormesis Effect after Low-Dose γ-Irradiation of Barley Seeds

Low-dose γ-irradiation can stimulate plant growth and development; however, the knowledge on the molecular mechanisms of such stimulation is yet fragmented. Irradiation of seeds leads to the mobilisation of endosperm resources and reallocation of available nitrogen to facilitate development. Based on the metabolomic analysis, several metabolites possibly involved in radiation stimulation were studied using the HPLC approach in barley cultivars after γ-irradiation of seeds. The comparison of changes in metabolite concentrations and changes in morphological traits after irradiation revealed seven metabolites that may be involved in the growth stimulation after γ-irradiation of barley seeds. Among them are free amino acids, such as γ-aminobutyric acid, β-alanine, arginine, lysine, glutamine, methionine, and a signalling compound methylglyoxal.

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Transcriptomic Analysis of Short-Term Salt Stress Response in Watermelon Seedlings

International Journal of Molecular Sciences ◽

10.3390/ijms21176036 ◽

2020 ◽

Vol 21 (17) ◽

pp. 6036

Author(s):

Qiushuo Song ◽

Madhumita Joshi ◽

Vijay Joshi

Keyword(s):

Amino Acids ◽

Salt Stress ◽

Amino Acid ◽

Photosystem Ii ◽

Free Amino Acids ◽

Free Amino ◽

Molecular Mechanisms ◽

Differentially Expressed ◽

Short Term ◽

Salt Stress Response

Watermelon (Citrullus lanatus L.) is a widely popular vegetable fruit crop for human consumption. Soil salinity is among the most critical problems for agricultural production, food security, and sustainability. The transcriptomic and the primary molecular mechanisms that underlie the salt-induced responses in watermelon plants remain uncertain. In this study, the photosynthetic efficiency of photosystem II, free amino acids, and transcriptome profiles of watermelon seedlings exposed to short-term salt stress (300 mM NaCl) were analyzed to identify the genes and pathways associated with response to salt stress. We observed that the maximal photochemical efficiency of photosystem II decreased in salt-stressed plants. Most free amino acids in the leaves of salt-stressed plants increased many folds, while the percent distribution of glutamate and glutamine relative to the amino acid pool decreased. Transcriptome analysis revealed 7622 differentially expressed genes (DEGs) under salt stress, of which 4055 were up-regulated. The GO analysis showed that the molecular function term “transcription factor (TF) activity” was enriched. The assembled transcriptome demonstrated up-regulation of 240 and down-regulation of 194 differentially expressed TFs, of which the members of ERF, WRKY, NAC bHLH, and MYB-related families were over-represented. The functional significance of DEGs associated with endocytosis, amino acid metabolism, nitrogen metabolism, photosynthesis, and hormonal pathways in response to salt stress are discussed. The findings from this study provide novel insights into the salt tolerance mechanism in watermelon.

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Transcriptome Analysis Reveals the Mechanism of Fluoride Treatment Affecting Biochemical Components in Camellia sinensis

International Journal of Molecular Sciences ◽

10.3390/ijms20020237 ◽

2019 ◽

Vol 20 (2) ◽

pp. 237 ◽

Cited By ~ 7

Author(s):

Jiaojiao Zhu ◽

Junting Pan ◽

Shouhua Nong ◽

Yuanchun Ma ◽

Anqi Xing ◽

...

Keyword(s):

Amino Acids ◽

Molecular Mechanism ◽

Bioactive Compounds ◽

Camellia Sinensis ◽

Free Amino Acids ◽

Free Amino ◽

Molecular Mechanisms ◽

Regulatory Genes ◽

Tea Leaves ◽

Fluoride Treatment

Tea (Camellia sinensis (L.) O. Kuntze), one of the main crops in China, is high in various bioactive compounds including flavonoids, catechins, caffeine, theanine, and other amino acids. C. sinensis is also known as an accumulator of fluoride (F), and the bioactive compounds are affected by F, however, the mechanism remains unclear. Here, the effects of F treatment on the accumulation of F and major bioactive compounds and gene expression were investigated, revealing the molecular mechanisms affecting the accumulation of bioactive compounds by F treatment. The results showed that F accumulation in tea leaves gradually increased under exogenous F treatments. Similarly, the flavonoid content also increased in the F treatment. In contrast, the polyphenol content, free amino acids, and the total catechins decreased significantly. Special amino acids, such as sulfur-containing amino acids and proline, had the opposite trend of free amino acids. Caffeine was obviously induced by exogenous F, while the theanine content peaked after two day-treatment. These results suggest that the F accumulation and content of bioactive compounds were dramatically affected by F treatment. Furthermore, differentially expressed genes (DEGs) related to the metabolism of main bioactive compounds and amino acids, especially the pivotal regulatory genes of catechins, caffeine, and theanine biosynthesis pathways, were identified and analyzed using high-throughput Illumina RNA-Seq technology and qRT-PCR. The expression of pivotal regulatory genes is consistent with the changes of the main bioactive compounds in C. sinensis leaves, indicating a complicated molecular mechanism for the above findings. Overall, these data provide a reference for exploring the possible molecular mechanism of the accumulation of major bioactive components such as flavonoid, catechins, caffeine, theanine and other amino acids in tea leaves in response to fluoride treatment.

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Pollen feeding proteomics: salivary proteins of the passion flower butterfly, Heliconius melpomene

10.1101/013128 ◽

2014 ◽

Author(s):

Desiree Harpel ◽

Darron A Cullen ◽

Swidbert Ott ◽

Chris D Jiggins ◽

James R Walters

Keyword(s):

Amino Acids ◽

Free Amino Acids ◽

Free Amino ◽

Molecular Mechanisms ◽

Chemical Degradation ◽

Salivary Proteins ◽

Carbohydrate Hydrolysis ◽

Pollen Feeding ◽

Heliconius Melpomene ◽

Heliconius Butterflies

While most adult Lepidoptera use flower nectar as their primary food source, butterflies in the genus Heliconius have evolved the novel ability to acquire amino acids from consuming pollen. Heliconius butterflies collect pollen on their proboscis, moisten the pollen with saliva, and use a combination of mechanical disruption and chemical degradation to release free amino acids that are subsequently re-ingested in the saliva. Little is known about the molecular mechanisms of this complex pollen feeding adaptation. Here we report an initial shotgun proteomic analysis of saliva from Heliconius melpomene. Results from liquid-chromatography tandem mass-spectrometry confidently identified 31 salivary proteins, most of which contained predicted signal peptides, consistent with extracellular secretion. Further bioinformatic annotation of these salivary proteins indicated the presence of four distinct functional classes: proteolysis (10 proteins), carbohydrate hydrolysis (5), immunity (6), and "housekeeping"(4). Additionally, six proteins could not be functionally annotated beyond containing a predicted signal sequence. The presence of several salivary proteases is consistent with previous demonstrations that Heliconius saliva has proteolytic capacity. It is likely these proteins play a key role in generating free amino acids during pollen digestion. The identification of proteins functioning in carbohydrate hydrolysis is consistent with Heliconius butterflies consuming nectar, like other lepidopterans, as well as pollen. Immune-related proteins in saliva are also expected, given that ingestion of pathogens is a very likely route to infection. The few "housekeeping" proteins are likely not true salivary proteins and reflect a modest level of contamination that occurred during saliva collection. Among the unannotated proteins were two sets of paralogs, each seemingly the result of a relatively recent tandem duplication. These results offer a first glimpse into the molecular foundation of Heliconius pollen feeding and provide a substantial advance towards comprehensively understanding this striking evolutionary novelty.

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Metabolic Profiling of γ-Irradiated Barley Plants Identifies Reallocation of Nitrogen Metabolism and Metabolic Stress Response

Dose-Response ◽

10.1177/1559325820914186 ◽

2020 ◽

Vol 18 (1) ◽

pp. 155932582091418 ◽

Cited By ~ 2

Author(s):

Polina Yu. Volkova ◽

G. Clement ◽

E. S. Makarenko ◽

E. A. Kazakova ◽

S. V. Bitarishvili ◽

...

Keyword(s):

Molecular Mechanisms ◽

Low Dose ◽

Metabolic Stress ◽

Growth Stimulation ◽

Significant Inhibition ◽

Gas Chromatography Mass Spectrometry ◽

High Dose ◽

Γ Irradiation ◽

Crop Species ◽

Nitrogen Redistribution

The favorable responses of crop species to low-dose γ irradiation can help to develop cultivars with increased productivity and improved stress tolerance. In the present study, we tried to reveal the candidate metabolites involved in growth stimulation of barley seedlings after applying low-dose γ-radiation (60Co) to seeds. Stimulating doses (5-20 Gy) provided a significant increase in shoot length and biomass, while relatively high dose of 100 Gy led to significant inhibition of growth. Gas chromatography–mass spectrometry metabolomic analysis uncovered several compounds that may take part in radiation hormesis establishment in irradiated plants. This includes molecules involved in nitrogen redistribution (arginine, glutamine, asparagine, and γ-aminobutyric acid) and stress-responsive metabolites, such as ascorbate, myo-inositol and its derivates, and free amino acids (l-serine, β-alanine, pipecolate, and GABA). These results contribute to the understanding of the molecular mechanisms of hormesis phenomenon.

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