Effects of tetracycline on growth, oxidative stress response, and metabolite pattern of ryegrass.

Tetracycline is an antibiotic that frequently contaminates the environment. In this study, the growth and metabolites of ryegrass seedlings treated with tetracycline (0, 1, 10 or 100 mg/L) for 5 days were investigated. The results showed that the growth of ryegrass and the concentrations of carotenoid and chlorophyll decreased as the tetracycline concentration increased. Tetracycline increased the production of reactive oxygen species (ROS) and cell permeability and triggered mitochondrial membrane potential loss in the roots of ryegrass. The metabolic profiles of ryegrass differed between the control and tetracycline-treated groups. The contents of glucose, shikimic acid, aconitic acid, serine, lactose, phenylalanine, mannitol, galactose, gluconic acid, asparagine, and glucopyranose were positively correlated with root length and had high variable importance projection values. These compounds may have crucial functions in root extension. Tetracycline also affected aminoacyl-tRNA biosynthesis, nitrogen metabolism, and alanine, aspartate and glutamate metabolism in the roots. Tetracycline may affect root extension by regulating the synthesis/degradation of these metabolites or the activity of their biosynthetic pathways. These results provide an insight into the stress response of ryegrass to tetracycline.

[Spectrometric determination of the content of nutritional elements in fruits of different red pear varieties].

A study was carried out on the contents of nutritional elements such as K, Fe, Zn, Ca, Cu, Mg and Mn in three different red pear varieties, namely Meirensu, Hongsucui and Mantianhongs, by flame atomic absorption. The results indicated that the linear relationships for different elements within the limits of working curves are good, and the range of recovery is 98%-104%, hence showing that the results asre satisfactory. There are abundant nutritional elements in fruits of the three different red pear varieties, meaning that they all have a relatively high nutritive value. In fruits of the three red pear varieties, the content sequence of different nutritional elements was found to be K>Fe>Zn>Ca>Cu>Mg>Mn. In fruits of the three different red pear varieties, the content sequence of K, Zn, Mg and Mn was Meirensu> Hongsucui>Mantianhong; the content sequence of Fe and Cu was Hongsucui>Mantianhong>Meirensu; and the content sequence of Ca was Mantianhong>Hongsucui> Meirensu; and the total content sequence of seven nutritional elements was Hongsucui>Meirensu>Mantianhong.