Highland barley, a characteristic cereal crop widely cultivated on the Qinghai-Tibet Plateau, riched in protein and various amino acids is an important functional food ingredient. The nutritional value of protein highly dependent on its amino acid composition. This paper systematically reviews the research progress on amino acids in highland barley:(1) Regarding composition and content, highland barley contains 18 amino acids, including 8 essential amino acids, generally exhibiting the characteristics of rich total amount and balanced proportions, with lysine being the first limiting amino acid. Significant differences in amino acid content are observed among different varieties and grain colors. (2) Regarding synthesis and regulation, the biosynthetic pathways of major amino acids and their molecular regulatory basis are outlined. (3) Regarding nutritional and health benefits, it focuses on elucidating the potential roles of functional components such as lysine and γ-aminobutyric acid (GABA) in supporting plateau residents' adaptation to high-metabolic and hypoxic environments, including providing high-quality protein, regulating blood glucose, and alleviating stress. (4) Regarding stress physiology, it reveals the key regulatory roles of amino acid metabolism, particularly the aromatic amino acid pathway, in highland barley's response to core plateau environmental stresses such as UV radiation, low temperature, and drought. (5) It summarizes the effects of different processing methods on the content, composition, and nutritional value of amino acids.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |