Sodium accumulation has minimal effect on metabolite profile of onion bulbs.

Onions (Allium cepa L.) are considered a salt-sensitive crop. However, to date, little evidence supports this claim and information about the physiological and metabolomic effects of Na+ accumulation in onion plants is lacking. The purpose of our research has been to assess changes in onion bulbs of three different cultivars after soil and foliar applications with moderate doses of chloride-free Na2SO4. The antioxidative defense mechanism in onion and the accumulation of Na+ within the plant has also been analyzed. Based on Na+ leaf and bulb concentrations, our findings demonstrate that Na+ is only transported from bulbs to leaves not vice versa, therefore foliar application does not lead to Na+ accumulation in the bulbs. Soil application with Na2SO4 results in an accumulation of Na+ in the leaves and bulbs, but with the exception of one onion variety this accumulation does not alter the metabolite profile of onions significantly. Even the K+ concentration and organic solute levels are unchanged after accumulation of Na+. Nevertheless, after Na2SO4 treatment, the antioxidative defense system moderately increases in onion bulbs. This study demonstrates that onion plants have the ability to exclude Na+ at moderate Na2SO4 treatment, and that the potential for quality onion production in soils with increased sodium concentration is much higher than previously assumed.

Metabolite profiling of onion landraces and the cold storage effect.

Today, commercial onion breeders focus almost entirely on conventional farming which reduces diversity in the market and leads to loss of desirable traits such as those that impact nutritional and sensory aspects of onions. A way to preserve phenotypic and genetic diversity is to re-evaluate traditional landraces to introduce their benefits to the broader public. Common onion genotypes vary greatly in their storability. In particular, temperature and relative humidity during storage have significant impact on the metabolites in onions after storage. The aim of this study was to assess changes in the metabolite profile of ten onion genotypes after five months of cold storage. In addition, a characterization of onion landraces in their fresh state was also conducted in order to compare their properties against a commercial genotype. Onion genotypes were grown under organic farming conditions. After harvest and curing, bulbs were stored for up to 22 weeks. Before and after storage, bulb samples were analyzed through targeted and untargeted methods. Out of 189 identified metabolites, 128 showed a storage effect. Mainly fructans decreased because of respiration and energy demand, while monosaccharides increased. Further, amino acids were altered in their concentration after storage with an effect on aroma precursors. Eight of the nine landraces had good storability without critical losses. In their fresh state, the onion genotypes clustered into three major groups. For instance, landraces of group III showed consistently and substantially higher levels of amino acids and certain sugars, indicating a high potential of aromatic properties in those onion landraces.

Effects of isoflavones on breast tissue and the thyroid hormone system in humans: a comprehensive safety evaluation.

Isoflavones are secondary plant constituents of certain foods and feeds such as soy, linseeds, and red clover. Furthermore, isoflavone-containing preparations are marketed as food supplements and so-called dietary food for special medical purposes to alleviate health complaints of peri- and postmenopausal women. Based on the bioactivity of isoflavones, especially their hormonal properties, there is an ongoing discussion regarding their potential adverse effects on human health. This review evaluates and summarises the evidence from interventional and observational studies addressing potential unintended effects of isoflavones on the female breast in healthy women as well as in breast cancer patients and on the thyroid hormone system. In addition, evidence from animal and in vitro studies considered relevant in this context was taken into account along with their strengths and limitations. Key factors influencing the biological effects of isoflavones, e.g., bioavailability, plasma and tissue concentrations, metabolism, temporality (pre- vs. postmenopausal women), and duration of isoflavone exposure, were also addressed. Final conclusions on the safety of isoflavones are guided by the aim of precautionary consumer protection.