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Background Yeast treatment has been used for purification of fructooligosaccharides (FOSs). However, the main drawback of this approach is that yeast can only partially remove sucrose from crude FOSs. The main objective of this research was to screen yeast strains for the capability of selectively consuming unwanted sugars, namely fructose, glucose, and sucrose, in crude FOSs extracted from red onion ( Allium cepa var. viviparum ) with minimal effect on FOS content. Results Among 43 yeast species isolated from Miang, ethnic fermented tea leaves, and Assam tea flowers, Candida orthopsilosis FLA44.2 and Priceomyces melissophilus FLA44.8 exhibited the greatest potential to specifically consume these unwanted sugars. In a shake flask, direct cultivation of C . orthopsilosis FLA44.2 was achieved in the original crude FOSs containing an initial FOSs concentration of 88.3 ± 1.2 g/L and 52.9 ± 1.2 g/L of the total contents of fructose, glucose, and sucrose. This was successful with 93.7% purity and 97.8% recovery after 24 h of cultivation. On the other hand, P . melissophilus FLA48 was limited by initial carbohydrate concentration of crude FOSs in terms of growth and sugar utilization. However, it could directly purify two-fold diluted crude FOSs to 95.2% purity with 92.2% recovery after 72 h of cultivation. Purification of crude FOSs in 1-L fermenter gave similar results to the samples purified in a shake flask. Extracellular β-fructosidase was assumed to play a key role in the effective removal of sucrose. Both Candida orthopsilosis FLA44.2 and P . melissophilus FLA44.8 showed γ-hemolytic activity, while their culture broth had no cytotoxic effect on viability of small intestinal epithelial cells, preliminarily indicating their safety for food processing. The culture broth obtained from yeast treatment was passed through an activated charcoal column for decolorization and deodorization. After being freeze dried, the final purified FOSs appeared as a white granular powder similar to refined sugar and was odorless since the main sulfur-containing volatile compounds, including dimethyl disulfide and dipropyl trisulfide, were almost completely removed. Conclusion The present purification process is considered simple and straight forward, and provides new and beneficial insight into utilization of alternative yeast species for purification of FOSs.

Main conclusion Storage at an elevated partial pressure of oxygen and classical artificial ageing cause a rapid loss of seed viability of short-lived vegetable seeds. Prolonging seed longevity during storage is of major importance for gene banks and the horticultural industry. Slowing down biochemical deterioration, including oxygen-dependent deterioration caused by oxidative processes can boost longevity. This can be affected by the seed structure and the oxygen permeability of seed coat layers. Classical artificial seed ageing assays are used to estimate seed 'shelf-life' by mimicking seed ageing via incubating seeds at elevated temperature and elevated relative humidity (causing elevated equilibrium seed moisture content). In this study, we show that seed lots of vegetable Allium species are short-lived both during dry storage for several months and in seed ageing assays at elevated seed moisture levels. Micromorphological analysis of the Allium cepa x Allium fistulosum salad onion seed identified intact seed coat and endosperm layers. Allium seeds equilibrated at 70% relative humidity were used to investigate seed ageing at tenfold elevated partial pressure of oxygen (high pO 2 ) at room temperature (22 ºC) in comparison to classical artificial ageing at elevated temperature (42 ºC). Our results reveal that 30 days high pO 2 treatment causes a rapid loss of seed viability which quantitatively corresponded to the seed viability loss observed by ~ 7 days classical artificial ageing. A similar number of normal seedlings develop from the germinating (viable) proportion of seeds in the population. Many long-lived seeds first exhibit a seed vigour loss, evident from a reduced germination speed, preceding the loss in seed viability. In contrast to this, seed ageing of our short-lived Allium vegetable seems to be characterised by a rapid loss in seed viability.

The objective of this study was to assess the toxicity of the insecticide esfenvalerate in Allium cepa , employing a multifaceted methodology. For this purpose, A. cepa bulbs were organized into four groups, one of which served as the control. The control group was exposed to tap water, while the remaining three groups were exposed to esfenvalerate at concentrations of 0.33 mg/L, 0.64 mg/L and 0.98 mg/L, respectively. The application of the highest dose of 0.98 mg/L esfenvalerate resulted in a significant decrease in physiological parameters, including a 51% reduction in rooting percentage, an 85.3% decrease in root elongation, and a 54.3% decrease in weight gain ( p  < 0.05). In the esfenvalerate-treated group (0.98 mg/L), a 45.7% decrease in mitotic index was observed, while a significant increase in chromosomal aberrations and micronucleus formation was observed compared to the control group ( p  < 0.05). The most frequently observed chromosomal abnormalities due to esfenvalerate were sticky chromosome, vagrant chromosome, fragment, unequal distribution of chromatin, bridge, vacuolated nucleus, reverse polarization and multipolar anaphase. Insecticide application could significantly increase the percentage of DNA tails up to 48.3%, as determined by the Comet test ( p  < 0.05). Exposure to 0.98 mg/L esfenvalerate increased malondialdehyde level (2.75-fold), proline level (1.96-fold), superoxide dismutase activity (1.35-fold), and catalase activity (1.69-fold) while reducing chlorophyll a level (58.18%) and chlorophyll b level (70.35%) ( p  < 0.05). Molecular docking analysis revealed that esfenvalerate can interact with tubulins, DNA topoisomerases, glutamate-1-semialdehyde aminotransferase, protochlorophyllide reductase and DNA molecules. Epidermis and cortex cell damages, cortex cell wall thickening, material accumulation in cortex cells and flattened cell nucleus were recorded as meristematic cell damages due to esfenvalerate. The toxicological profile of esfenvalerate on A. cepa exhibited dose dependence. While esfenvalerate-induced oxidative stress is the most probable cause of toxicity, direct interaction with DNA and other molecules that play a crucial role in maintaining cell integrity may also be among the mechanisms of toxicity. The study’s findings emphasize that esfenvalerate poses a risk to non-target organisms, underscoring the need for a reassessment of its regulations and further research into its toxicity.

Lou onion (Allium fistulosum L. var. viviparum) is an abundant source of flavonols which provides additional health benefits to diseases. Genome-wide specific length amplified fragment (SLAF) sequencing method is a rapidly developed deep sequencing technologies used for selection and identification of genetic loci or markers. This study aimed to elucidate the genetic diversity of 122 onion accessions in China using the SLAF-seq method. A set of 122 onion accessions including 107 A.fistulosum L. var. viviparum Makino, 3 A.fistulosum L. var. gigantum Makino, 3 A.mongolicum Regel and 9 A.cepa L. accessions (3 whites, 3 reds and 3 yellows) from different regions in China were enrolled. Genomic DNA was isolated from young leaves and prepared for the SLAF-seq, which generated a total of 1,387.55 M reads and 162,321 high quality SNPs (integrity >0.5 and MAF >0.05). These SNPs were used for the construction of neighbor-joining phylogenetic tree, in which 10 A.fistulosum L. var. viviparum Makino accessions from Yinchuan (Ningxia province) and Datong (Qinghai province) had close genetic relationship. The 3 A.cepa L. clusters (red, white and yellow) had close genetic relationship especially with the 97 A.fistulosum L. var. viviparum Makino accessions. Population structure analysis suggested entire population could be clustered into 3 groups, while principal component analysis (PCA) showed there were 4 genetic groups. We confirmed the SLAF-seq approach was effective in genetic diversity analysis in red onion accessions. The key findings would provide a reference to the Lou onion germplasm in China.

Uranium compounds, particularly uranyl acetate, are known to cause significant genotoxic and oxidative damage in biological systems due to their high chemical reactivity. In recent years, plant-based antioxidants, such as those found in Abelmoschus esculentus (L.) Moench, have attracted considerable attention for their potential to mitigate the toxicity of heavy metals. The present study was conducted to investigate the mitigative effect of A. esculentus (L.) Moench extract on the toxicity induced by uranyl acetate in the model organism Allium cepa L. Tap water, 250 mg L − 1 A. esculentus extract, 500 mg L − 1 A. esculentus extract, 0.1 mg mL − 1 uranyl acetate, 0.1 mg mL − 1 uranyl acetate + 250 mg L − 1 A. esculentus extract, and 0.1 mg mL − 1 uranyl acetate + 500 mg L − 1 A. esculentus extract were administered to the six groups of A. cepa bulbs. The group treated with tap water served as control group. Uranyl acetate caused a significant reduction in rooting percentage, root elongation, weight gain, mitotic index and the levels of chlorophyll a and chlorophyll b. There was a notable increase in the frequency of micronuclei and chromosomal aberrations (CAs), as well as a rise in malondialdehyde level following the uranyl acetate administration. The uranyl acetate-induced CAs included fragment, sticky chromosome, vagrant chromosome, bridge and unequal distribution of chromatin. The group treated with uranyl acetate also exhibited elevated levels of DNA damage, meristematic cell injury and superoxide dismutase and catalase enzyme activities. The meristematic damage induced by uranyl acetate was observed in the epidermis, cortex and nucleus of epidermal cells. The A. esculentus extract was observed to possess high levels of phenolic compounds and exhibited dose-dependent efficacy in mitigating the adverse effects of uranyl acetate. According to LC/MS analysis, the most abundant phenolic compounds in A. esculentus extract were rutin, caffeic acid, quercetin, salicylic acid and 4-OH benzoic acid. It was concluded that the capacity of A. esculentus extract to reduce uranyl acetate-induced multidirectional toxicity may be related to the ability of its phenolic compounds to chelate and scavenge radicals.

The growth of industrialization growth the risk of vanadium (V) contamination. The objective of this study was to examine the impact of 200 µg L − 1 VCI 3 -induced toxicity as well as the potential protective effect of 187.5 mg L − 1 and 375 mg L − 1 Hypericum perforatum ( H. perforatum ) extracts against this toxicity on the Allium cepa ( A. cepa ) model organism. For this purpose, a series of investigations were conducted on the growth physiology alterations (germination percentage, root elongation, weight gain), cytogenetic alterations (mitotic index, micronucleus, chromosomal aberrations), biochemical alterations (malondialdehyde, superoxide dismutase, catalase) and defects in meristematic tissue in A. cepa. In addition, the phenolic compound content of H. perforatum extract was determined by the LC/MS-MS method. V application negatively affected all the investigated parameters and caused a serious phytotoxic and genotoxic effect as well as oxidative stress in A. cepa . Conversely, no statistical difference was observed between the parameters of the groups treated with H. perforatum extract and those of the control group. The administration of H. perforatum extract combined with V resulted in a notable enhancement in germination percentage, root elongation, weight gain, mitotic index value, chlorophyll a level and chlorophyll b level. Additionally, it led to a reduction in micronucleus and chromosomal aberrations frequencies, as well as meristematic tissue defects. Furthermore, LC/MS-MS analysis demonstrated that H. perforatum extract contains phenolic compounds, including catechin, epicatechin, quercetin, oleuropein and rutin, which confer antioxidant properties to the extract. The study provided clear evidence that H. perforatum extract attenuates the toxic effects of V in A. cepa , which can be attributed to its high content of bioactive phenols. The findings of the study indicate that H. perforatum extract may serve as a protective natural agent for daily use against heavy metal toxicity.

Mercury (Hg) is a highly toxic heavy metal for all organisms. In the present study, the mitigative role of 190 mg/L and 380 mg/L doses of green tea extract (GTex) against mercury(II) chloride (HgCI 2 )-induced toxicity was evaluated in Allium cepa L. For this aim, selected physiological, genotoxicity, and biochemical parameters as well as meristematic cell injuries in the roots were investigated. Ratios of catechin and caffeine in GTex were determined by HPLC analysis. Also, free radical scavenging activity of GTex was tested against superoxide and hydrogen peroxide radicals. As a result of HgCI 2 application, germination percentage, root elongation, weight gain, and mitotic index (MI) declined, while the frequency of micronucleus (MN), chromosomal abnormalities (CAs), and meristematic cell damages increased. HgCI 2 administration also led to a significant increase in malondialdehyde content, superoxide dismutase, and catalase activities which are signs of oxidative stress. On contrary, applications of GTex together with HgCI 2 reduced HgCI 2 -induced adverse effects in all parameters in a dose-dependent manner. Antioxidant components in GTex were listed as caffeine, epigallocatechin gallate, epigallocatechin, epicatechin gallate, and catechin according to their abundance. GTex exhibited a strong scavenging ability in the presence of superoxide and hydrogen peroxide radicals. The present study revealed the strong protective capacity of GTex against HgCI 2 -induced toxicity in A. cepa owing to its high antioxidant content with a multifaceted perspective. With this study, a reliable starting point was established for future studies investigating the more common and diverse use of GTex against toxic substances.

This study was designed to assess the recovery effect of pomegranate seed extract (PSEx) against nickel (Ni)-induced damage in Allium cepa . Except for the control group treated with tap water, five experimental groups were exposed to 265 mg L −1 PSEx, 530 mg L −1 PSEx, 1 mg L −1 NiCI 2 , 265 mg L −1 PSEx + 1 mg L −1 NiCI 2 , and 530 mg L −1 PSEx + 1 mg L −1 NiCI 2 , respectively. The toxicity of Ni was examined through the analysis of physiological (germination percentage, weight gain, and root length), cytotoxicity (mitotic index), genotoxicity (micronucleus, chromosomal anomalies, and Comet test), and biochemical (malondialdehyde, proline, chlorophyll a and chlorophyll b contents, the activities of superoxide dismutase and catalase) parameters. Meristematic cell defects were also investigated. The NiCl 2 -DNA interaction was evaluated through spectral shift analysis. Values of all physiological parameters, mitotic index scores, and chlorophyll contents decreased while micronucleus frequency, DNA tail percentage, chromosomal anomalies, proline, MDA, and enzyme activities increased following Ni administration. According to the tail DNA percentage scale, Ni application caused “high damage” to DNA. Ni-induced chromosomal anomalies were fragment, sticky chromosome, vagrant chromosome, bridge, unbalanced chromatin distribution, reverse polarization, and nucleus with bud. NiCl 2 -DNA interaction caused a hyperchromic shift in the UV/Vis spectrum of DNA by spectral profile analysis. Ni exposure impaired root meristems as evidenced by the formation of epidermis cell damage, flattened cell nucleus, thickened cortex cell wall, and blurry vascular tissue. Substantial recovery was seen in all parameters with the co-administration of PSEx and Ni. Recovery effects in the parameters were 18–51% and 41–84% in the 265 mg L −1 PSEx + 1 mg L −1 NiCI 2 and 530 mg L −1 PSEx + 1 mg L −1 NiCI 2 groups, respectively. The Comet scale showed that PSEx applied with Ni reduced DNA damage from “high” to “moderate.” Ni-induced thickened cortex cell wall and blurry vascular tissue damage disappeared completely when 530 mg L −1 PSEx was mixed with Ni. PSEx successfully reduced the negative effects of Ni, which can be attributed to its content of antioxidants and bioactive ingredients.

As the use of insect growth regulators such as triflumuron becomes more prevalent in modern agriculture, concerns have emerged regarding their multifaceted toxicity in non-target species. In this study, the multifaceted toxicity of triflumuron insecticide in the non-target bioindicator organism Allium cepa L. was investigated. For this purpose, the physiological effects of triflumuron on A. cepa bulbs (germination percentage, weight gain, and root elongation) were screened. In addition, cytogenetic (chromosomal abnormalities = CAs, micronucleus = MN, mitotic index = MI, and DNA damage = Comet analysis) and biochemical (superoxide dismutase = SOD and catalase = CAT enzyme activities, malondialdehyde = MDA and proline accumulation, and chlorophyll a and chlorophyll b amounts) analyses were performed in A. cepa root tip cells exposed to triflumuron. Root tip meristematic cell damage was also among the parameters examined. Onion bulbs were divided into 4 groups. The control group was treated with tap water. The other 3 groups were treated with 1.6 µg/L triflumuron, 10.0 µg/L triflumuron and 24.2 µg/L triflumuron, respectively. The selected triflumuron doses were based on LC₅₀ values reported for aquatic and terrestrial organisms to reflect environmentally relevant exposure levels. The application period lasted 72 h for root development and 144 h for leaf growth required for chlorophyll analysis. Triflumuron insecticide significantly reduced germination, root elongation, and weight gain in all groups. The decline in the values of physiological parameters was exacerbated with increasing dose of triflumuron. Triflumuron administration increased the frequency of MN and CAs, and decreased MI. CAs induced in the triflumuron-exposed groups were ranked according to their frequency as sticky chromosome, fragment, vagrant chromosome, unequal distribution of chromatin and bridge. Comet assay showed a considerable increase in the percentage of tail DNA. Genotoxicity arising from triflumuron was found to be dose-dependent. Triflumuron caused a significant increase in MDA and proline levels and antioxidant enzyme activities and a significant decrease in chlorophyll a and chlorophyll b levels in direct proportion to the application concentration. In the control group, A. cepa root tip meristem cells were normal and healthy. Meristem cell damage, cortex cell damage, cortex cell wall thickening, and flattened cell nuclei were observed in A. cepa root cells treated with triflumuron insecticide. In conclusion, triflumuron is a toxic chemical to A. cepa and toxicity is both multifaceted and tends to increase with increasing doses of triflumuron.

Potato onion ( Allium cepa var. aggregatum G. Don) remained the most widely grown onion type in Finland up to the 1950’s, after which the more productive cultivars of common onion replaced this vegetatively propagated onion type. The Finnish accessions have been maintained in two national plant genetic resources (PGR) collections since 1990’s but new samples have been obtained still later. In this research, we analysed the genetic diversity of potato onions and shallots, grown in home gardens and in PGR collection, and compared the uniformity of the two PGR collections. One hundred ten onion samples were analysed using eight microsatellite loci, which amplified 83 alleles in total. There was a large number of genetically different samples, forming four major groups in the dendrogram. The results show that there is still a lot of genetic diversity among the Finnish potato onions, even though they are propagated vegetatively. The rich diversity in the samples obtained from citizens reflects a valuable source of genetic resources maintained by home gardeners. The national collection has been updated on the basis of the results. To ensure the preservation of the rich onion heritage, efforts are needed to increase the availability of potato onion to home gardeners and commercial growers.