Distinct Quality Changes of Garlic Bulb during Growth by Metabolomics Analysis

Photoperiod and temperature as dominant environmental drivers triggering chemical compositions of garlic bulb during growth

Photoperiod and temperature are crucial for plant growth and development, but the accumulation patterns and regulatory mechanisms of garlic in response to these factors remain unclear. Compared to normal conditions (12/12 h light/dark; 22/15 °C day/night), increasing the photoperiod by 1 h each month with normal temperature (13/11, 14/10, 15/9, 16/8 h; light/dark; 22/15 °C day/night) or increasing photoperiod by 1 h with a 1.5 °C increase in temperature (13/11, 14/10, 15/9, 16/8 h light/dark; 23.5/16, 25/17, 26.5/18, 28/19 °C day/night) at monthly intervals substantially affects garlic growth in early G204, mid-G666, and late G390 harvest cultivars. For both increased photoperiod and temperature, the environment most favorable for bulb growth is characterized by the maximum accumulation of hormones (IAA, JA, and ZT) during bulb formation, while higher levels of ACC, phenolic acids, and organosulfur compounds are observed during the harvesting stage. Furthermore, the accumulation patterns of alliin and allicin in garlic bulbs for G204, G666, and G390 cultivars significantly increased, with fold changes of (2.0, 1.8, and 1.9) and (1.8, 1.7, and 1.5), respectively, in response to increased photoperiod and temperature conditions. Additionally, the accumulation pattern in G204, and G666 was similar but notably distinct from late harvest G390 during growth. In this study, metabolomics models were constructed to assess chemical composition variations and predict the differences among three garlic varieties during the growth stages. These models revealed functional component variations and provided reliable predictions, offering valuable insights for estimating garlic chemical compositions and identifying optimal environmental conditions for growth.

Development of an analytic method for organosulfur compounds in Welsh onion and its use for nutritional quality analysis of five typical varieties in China

A reliable, simple, and sensitive method capable of quantifying six organosulfur compounds (OSCs) was established. The samples were extracted by water containing 3 % formic acid with a simple vortex, ultrasound, and centrifugation step, and the solutions were analyzed by ultra-high-performance liquid chromatography separation system coupled with a triple-quadrupole mass spectrometry (UHPLC - MS/MS). Then the method was applied for the analysis of six OSCs in five varieties of two types Welsh onions in China, and the moisture content, reducing sugar, total polyphenols, and 21 free amino acids were also analyzed to study the characters of these Welsh onions intensively. Multivariate statistical analysis was used to investigate the differences in OSCs and free amino acids profiles among the samples. This study showed that enzymatic inhibition method combined with UHPLC - MS/MS is an effective technique to analyze OSCs in Welsh onion, and could be valuable for the routine quantitation of OSCs in other foods.

Monitoring Changes in Biochemical and Metabolite Profiles in Garlic Cloves during Storage

Storage is important for the garlic cloves industry because it is critical to enabling a year-round supply. This study aimed to investigate the changes in biochemical and metabolic profiles in garlic cloves in terms of different temperatures and cultivars during storage using nontargeted and targeted metabolomics. The results showed that the storage temperatures and times were important factors affecting the composition and metabolite content of garlic cloves. In detail, the metabolic profiling of garlic cloves changed significantly at 22 °C, which was mainly related to sprouting. Furthermore, γ-glutamyl peptide was converted into the corresponding flavor precursors or free amino acids, leading to the fluctuation in the amount of nutrients in garlic cloves. In contrast, the quality of garlic cloves remained stable for 290 days at 0 °C though metabolism still occurred, which indicated that the slight chemical changes did not impact the quality significantly and low temperature could prolong their dormancy.

Comprehensive widely targeted metabolomics to decipher the molecular mechanisms of Dioscorea opposita thunb. cv. Tiegun quality formation during harvest

Dioscorea opposita Thumb. cv. Tiegun is commonly consumed as both food and traditional Chinese medicine, which has a history of more than two thousand years. Harvest time directly affects its quality, but few studies have focused on metabolic changes during the harvesting process. Here, a comprehensive metabolomics approach was performed to determine the metabolic profiles during six harvest stages. Thirty eight metabolites with significant differences were determined as crucial participants. Related metabolic pathways including phenylalanine, tyrosine and tryptophan biosynthesis, stilbenoid, diarylheptanoid and gingerol biosynthesis, phenylpropanoid biosynthesis, flavonoid biosynthesis and tryptophan metabolism were the most active pathways during harvest. The results revealed that temperature has a significant impact on quality formation, which suggested that Dioscorea opposita thumb. cv. Tiegun harvested after frost had higher potential value of traditional Chinese medicine. This finding not only offered valuable guidance for yam production, but also provided essential information for assessing its quality.

Distinct Quality Changes of Asparagus during Growth by Widely Targeted Metabolomics Analysis

Asparagus is a popular vegetable and traditional medicine consumed worldwide due to its health benefits. The quality of asparagus, mainly attributed to small components like flavonoids and steroid, is quite differential as a result of different environments and maturities. However, the accumulation pattern and regulatory mechanism of metabolites in asparagus remain unclear so far. Herein, widely targeted metabolomics analysis was employed to study the quality and chemical composition variances of four asparagus, including three green asparagus of different maturities and one white asparagus. A total of 1045 metabolites were annotated in asparagus in which flavonoids and phenolic acids accounted for 37.51% of the total. Green asparagus was found to be rich in flavonoids, while white asparagus contained more steroids. Additionally, 461 biomarkers were screened between matured green and white asparagus, which is much more than that filtered among three green asparagus at different growth stages. These results indicated that sunlight has a stronger effect on the metabolism of asparagus compared to the general development of asparagus. Linoleic acid metabolism and alpha-linolenic acid metabolism were active during green asparagus growth, while flavone and flavonol biosynthesis and flavonoid biosynthesis resulted as two of the most important pathways when asparagus was exposed to sunlight.

Advances in Accurate Quantification Methods in Food Analysis

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Transcriptome Characterization of the Roles of Abscisic Acid and Calcium Signaling during Water Deficit in Garlic

Garlic (Allium sativum L.) is one of the most important vegetable crops, and breeding drought-tolerant varieties is a vital research goal. However, the underlying molecular mechanisms in response to drought stress in garlic are still limited. In this study, garlic seedlings were subjected to 15% PEG6000 for 0, 1, 4, and 12 h, respectively, to simulate drought stress. Changes of transcriptomes as a result of drought stress in garlic leaves were determined by de novo assembly using the Illumina platform. In total, 96,712 unigenes and 11,936 differentially expressed genes (DEGs) were identified in the presence of drought conditions. Transcriptome profiling revealed that the DEGs were mainly enriched in the biosynthesis of secondary metabolites, MAPK signaling pathway, starch and sucrose metabolism, phenylpropanoid biosynthesis, and plant hormone signal transduction. Genes involved in abscisic acid and calcium signaling were further investigated and discussed. Our results indicated that a coordinated interplay between abscisic acid and calcium is required for drought-induced response in garlic.

Metabolic Changes in Different Tissues of Garlic Plant during Growth

The accumulation, distribution, and transportation of nutrients in different tissues of garlic during growth are unclear. Thereby, five tissues (leaf, pseudostem, bulb wrapper, clove skin, and clove) collected at 7 weeks were subjected to metabolomics analysis. A total of 84 biomarkers were identified during garlic plant growth. Most organosulfur compounds, amino acids, and dipeptides were upregulated in the clove, while a reversed trend was observed in other tissues. In addition, nucleotides and alkaloids increased because of senescence in the last 2 weeks except for the clove. The results also indicated that the garlic plant at an early stage is an ideal vegetable that is rich in nutrients. When the leaves began to wither, most nutrients were transported from other tissues to cloves, and the content of 7 total flavor precursors and 20 total amino acids in the clove increased by 113% and 65% after week 5, respectively. Therefore, delayed harvest may improve the nutritional quality of garlic bulbs.