Comparative Studies of Bioactivities and Chemical Components in Fresh and Black Garlics.

To investigate the bioactivities of fresh garlic and its processed product, black garlic, we conducted comparative analyses of antioxidant, anti-inflammatory, innate immune activation, and anti-cancer activities in addition to the chemical composition (sugar, amino acid, and polyphenol contents) of these materials. Simultaneous assay using neutrophil-like cells showed that fresh garlic exhibited antioxidant and innate immunostimulatory activities, whereas black garlic displayed a potent anti-inflammatory effect. The antioxidant activity index was correlated with phenol and flavonoid contents, while the innate immunostimulatory activity was correlated with fructan content. Furthermore, some black garlics with low fructose content were found to inhibit the proliferation of UM-UC-3 cancer cells, while other black garlics rich in fructose increased UM-UC-3 cell proliferation. It was shown that the processing of fresh garlic could change the composition of sugars, antioxidants, and amino acids, which have different effects on neutrophil-like cells and UM-UC-3 cells, as well as on bioactivities.

Comprehensive Metabolite Profiling in Genetic Resources of Garlic (Allium sativum L.) Collected from Different Geographical Regions.

Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits.

Metabolome-Based Discrimination Analysis of Shallot Landraces and Bulb Onion Cultivars Associated with Differences in the Amino Acid and Flavonoid Profiles.

Shallot landraces and varieties are considered an important genetic resource for Allium breeding due to their high contents of several functional metabolites. Aiming to provide new genetic materials for the development of a novel bulb onion cultivar derived from intraspecific hybrids with useful agronomic traits from shallots, the metabolic profiles in the bulbs of 8 Indonesian shallot landraces and 7 short-day and 3 long-day bulb onion cultivars were established using LC-Q-TOF-MS/MS. Principal component analysis, partial least squares discriminant analysis, and dendrogram clustering analysis showed two major groups; group I contained all shallot landraces and group II contained all bulb onion cultivars, indicating that shallots exhibited a distinct metabolic profile in comparison with bulb onions. Variable importance in the projection and Spearman's rank correlation indicated that free and conjugated amino acids, flavonoids (especially metabolites having flavonol aglycone), and anthocyanins, as well as organic acids, were among the top metabolite variables that were highly associated with shallot landraces. The absolute quantification of 21 amino acids using conventional HPLC analysis showed high contents in shallots rather than in bulb onions. The present study indicated that shallots reprogrammed their metabolism toward a high accumulation of amino acids and flavonoids as an adaptive mechanism in extremely hot tropical environments.

Compartmentation and localization of bioactive metabolites in different organs of Allium roylei.

To investigate the involvement of Allium roylei metabolites in the plant's defenses, a comprehensive analysis of the content of cysteine sulfoxides, flavonols, polyphenols, ascorbic acid, and saponins was carried out in the various organs of this species. Metabolomics high performance liquid chromatography (HPLC), spectral-based analysis, and histochemcial studies have given important insight to the validity of saponins as a key component involved in plant protection. The root-basal stem, bulb, and leaf extracts exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with inhibition concentration (IC(50)) ranging from 0.649 to 0.757 mg/mL. The antimicrobial properties of the saponin and flavonoid crude extracts were evaluated. The saponin extracts demonstrated significant antifungal activity depending on the applied concentration, and the growth inhibition rate of the tested fungal pathogens ranged from 1.07 to 47.76%. No appreciable antibacterial activity was recorded in the same sample.

Effects of Drought Stress on Abscisic Acid Content and Its Related Transcripts in Allium fistulosum-A. cepa Monosomic Addition Lines.

Climate change has resulted in an increased demand for Japanese bunching onions (Allium fistulosum L., genomes FF) with drought resistance. A complete set of alien monosomic addition lines of A. fistulosum with extra chromosomes from shallot (A. cepa L. Aggregatum group, AA), represented as FF + 1A-FF + 8A, displays a variety of phenotypes that significantly differ from those of the recipient species. In this study, we investigated the impact of drought stress on abscisic acid (ABA) and its precursor, ß-carotene, utilizing this complete set. In addition, we analyzed the expression levels of genes related to ABA biosynthesis, catabolism, and drought stress signal transduction in FF + 1A and FF + 6A, which show characteristic variations in ABA accumulation. A number of unigenes related to ABA were selected through a database using Allium TDB. Under drought conditions, FF + 1A exhibited significantly higher ABA and ß-carotene content compared with FF. Additionally, the expression levels of all ABA-related genes in FF + 1A were higher than those in FF. These results indicate that the addition of chromosome 1A from shallot caused the high expression of ABA biosynthesis genes, leading to increased levels of ABA accumulation. Therefore, it is expected that the introduction of alien genes from the shallot will upwardly modify ABA content, which is directly related to stomatal closure, leading to drought stress tolerance in FF.

Targeted Metabolome Profiling of Indonesian Shallots and Japanese Long-Day/Short-Day Bulb Onions.

In this study, targeted metabolome analysis was applied to identify the discriminative metabolites between Indonesian shallot landraces, Japanese long-day onion (LDO) varieties, and Japanese short-day onion (SDO) varieties. In total, 172 metabolite signal intensities were subjected to multivariate PLS-DA, VIP, and random forest modeling to gain further insight into genotype-specific metabolites. PLS-DA divides the examined genotypes into three different clusters, implying that shallot landraces exhibited a distinct metabolite profile compared with Japanese LDO and SDO varieties. The PLS-DA, VIP, and random forest results indicated that the shallot and LDO are richer in metabolite constituents in comparison with the SDO. Specifically, amino acids and organosulfur compounds were the key characteristic metabolites in shallot and LDO genotypes. The analysis of S-alk(en)yl-L-cysteine sulfoxide (ACSO) compounds showed higher accumulation in the shallot landraces relative to LDO and SDO varieties, which explains the stronger pungency and odor in shallots. In addition, the LDO showed higher ACSO content compared with the SDO, implying that long-day cultivation might enhance sulfur assimilation in the Japanese onion. The LDO 'Super Kitamomiji' and the shallots 'Probolinggo' and 'Thailand' showed higher ACSO content than other varieties, making it useful for Allium breeding to improve the flavor and stress tolerance of onions.

Widely targeted metabolome and transcriptome landscapes of Allium fistulosum-A. cepa chromosome addition lines revealed a flavonoid hot spot on chromosome 5A.

Here, we report a comprehensive analysis of the widely targeted metabolome and transcriptome profiles of Allium fistulosum L. (FF) with the single extra chromosome of shallot [A. cepa L. Aggregatum group (AA)] to clarify the novel gene functions in flavonoid biosynthesis. An exhaustive metabolome analysis was performed using the selected reaction monitoring mode of liquid chromatography-tandem quadrupole mass spectrometry, revealing a specific accumulation of quercetin, anthocyanin and flavone glucosides in AA and FF5A. The addition of chromosome 5A from the shallot to A. fistulosum induced flavonoid accumulation in the recipient species, which was associated with the upregulation of several genes including the dihydroflavonol 4-reductase, chalcone synthase, flavanone 3-hydroxylase, UDP-glucose flavonoid-3-O-glucosyltransferase, anthocyanin 5-aromatic acyltransferase-like, pleiotropic drug resistance-like ATP binding cassette transporter, and MYB14 transcriptional factor. Additionally, an open access Allium Transcript Database (Allium TDB, http://alliumtdb.kazusa.or.jp ) was generated by using RNA-Seq data from different genetic stocks including the A. fistulosum-A. cepa monosomic addition lines. The functional genomic approach presented here provides an innovative means of targeting the gene responsible for flavonoid biosynthesis in A. cepa. The understanding of flavonoid compounds and biosynthesis-related genes would facilitate the development of noble Allium varieties with unique chemical constituents and, subsequently, improved plant stress tolerance and human health benefits.

Diversity evaluation based on morphological, physiological and isozyme variation in genetic resources of garlic (Allium sativum L.) collected worldwide.

The aim of this study was to obtain primary information about the global diversity of garlic (Allium sativum L.) by evaluating morphological, physiological and isozyme variation. A total of 107 garlic accessions collected worldwide were grown in Yamaguchi, Japan. Five morphological traits (bulb weight, bulb diameter, number of cloves per bulb, number of bulbils and scape length) and one physiological trait (bolting period) of the collected garlic showed wide variation. Meanwhile, a total of 140 garlic accessions, including the 107 mentioned above, were characterized by leucine aminopeptidase (LAP) and phosphoglucoisomerase (PGI) isozyme analyses; they clearly showed polymorphisms in putative isozyme loci (Lap-1, Lap-2 and Pgi-1). Allelic frequencies were estimated in each group of accessions categorized by their geographical origin, and the observed (Ho) and expected (He) heterozygosities were calculated. The allelic frequencies differed between groups. A principal component analysis based on morpho-physiological data indicated a grouping of the garlic accessions into Central Asian and Northern Mediterranean groups as well as others. We discuss the roles of artificial and natural selection that may have caused differentiation in these traits, on the assumption that ancestral domesticated garlic populations have adapted in various regions using standing variation or mutations that accumulated during expansion, and have evolved along with human-preferred traits over a long history of cultivation.