Characterization of Flavor Compounds in Chinese Indigenous Sheep Breeds Using Gas Chromatography-Ion Mobility Spectrometry and Chemometrics.

This study analyzed the flavor compounds in the meat of four indigenous breeds of Chinese sheep through the use of gas chromatography-ion mobility spectrometry (GC-IMS). GC-IMS provided information on the characteristics and strength of 71 volatile flavor compounds (monomers and dimers), with aldehydes, alcohols and ketones being the most abundant in all types of sheep meat. The compounds with higher intensity peaks in the sheep meat were aldehydes (n-nonanal, octanal, heptanal, 3-methylbutanal, and hexanal), alcohols (1-octen-3-ol, hexanol, and pentanol), ketones (3-hydroxy-2-butanon, 2-butanone, and 2-propanone), esters (methyl benzoate), and thiazole (trimethylthiazole). The volatile flavor components in the meat of the different breeds of sheep obtained via GC-IMS were further differentiated using principal component analysis. In addition, orthogonal partial least squares discriminant analysis (OPLS-DA) and variable importance on projection (VIP) were used to determine the characteristic flavor compounds in the meats of different breeds of sheep, and 21 differentially volatile components were screened out based on having a VIP above 1. These results indicate that GC-IMS combined with multivariate analysis is a convenient and powerful method for characterizing and discriminating sheep meat.

Nitrate_dependent suberization regulates cadmium uptake and accumulation in maize.

In this study, effect of nitrate-dependent suberization in maize root on cadmium (Cd) uptake and accumulation was investigated. Suberization in maize roots was significantly lower in plants grown with a high nitrate supply compared with low nitrate. This decrease was seen in the total amount of suberin, in which the aliphatic suberin amount was significantly decreased, whereas no difference in aromatic suberin content between different N-treatments. RNA-sequencing showed that suberin biosynthesis genes were upregulated in low nitrate treatment, which correlated well with the increased suberin content. Bioimaging and xylem sap analysis showed that reduced exodermal and endodermal suberization in roots of plants grown under high nitrate promoted radial Cd transport along the crown root. The enhanced suberization in crown roots of plants grown in low nitrate restricted the radial transport of Cd from epidermis to cortex via decreased accessibility to Cd related transporters at the plasmalemma. Also, under low nitrate supply, the Cd transport gene ZmNramp5 was upregulated in the crown root, which may enhance Cd uptake by root tip where exodermis and endodermis were not fully suberized. These results suggest that high nitrate supply enhances Cd uptake and radial transport in maize roots by reducing exodermal and endodermal suberization.