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.     

Physicochemical Properties of the Protic Ionic Liquid Bis(2-hydroxyethyl)methylammonium Formate

A protic ionic liquid, bis(2-hydroxyethyl)methylammonium formate, (BHEMF), was synthesized and characterized. The density and surface tension of the protic ionic liquid were determined in the temperature range of 293.15?C343.15?K. The molar volume and surface entropy were estimated from the experimental density and surface tension data, respectively. In terms of Glasser??s theory, the standard molar entropy and lattice energy of the protic ionic liquid were estimated. Using the methods of Kabo and Rebelo, the molar enthalpy vaporization of the protic ionic liquid, $ ^{l} \Updelta^{g}H_{\text{m}}^{0} $ (298.15?K) at 298.15?K and $ ^{l} \Updelta^{g}H_{\text{m}}^{0} $ (T _b), at the hypothetical normal boiling point were estimated, respectively. According to the interstical model, the thermal expansion coefficient of the protic ionic liquid, ??, was calculated and the result is in very good agreement with the experimental value.