Evidence of calycosin-7-O-β-d-glucoside's role as a major antioxidant molecule of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao plants under freezing stress

• Published in: Environmental and experimental botany Vol. 109; pp. 1 - 11
• Main Authors: Pan, Haiyun, Li, Xiaobing, Cheng, Xiaowei, Wang, Xiaoqiang, Fang, Changming, Zhou, Tongshui, Chen, Jiakuan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2015
• Subjects: Astragalus; Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao; Calycosin-7-O-β-d-glucoside; Freezing tolerance; Isoflavonoid; Phenylalanine ammonia lyase; Calycosin-7-O-β-d-glucoside; Freezing tolerance; Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao; Phenylalanine ammonia lyase; Isoflavonoid
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/j.envexpbot.2014.07.013

The accumulation of calycosin-7-O-β-d-glucoside in Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao plants is a significant factor in the prevention of freezing stress. •The plant groups with different isoflavonoid content were established using an enzyme inhibitor.•Calycosin-7-O-β-d-glucoside as a major antioxidant molecule of the plant in vivo under freezing stress.•Calycosin-7-O-β-d-glucoside is also associated with the development of antioxidant enzyme activity. It was previously demonstrated that a significant increase in calycosin-7-O-β-d-glucoside (CG), the major isoflavonoid in roots of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao, is induced under low temperatures. To reveal its physiological functions under stress, seedlings with different isoflavonoid levels were established using a phenylalanine ammonia lyase (PAL) enzyme inhibitor, l-α-aminooxy-β-phenylpropionic acid (AOPP). Changes in the content of malondialdehyde (MDA), activities of antioxidant enzymes and levels of isoflavonoids were monitored in leaves and roots of this plant during 72h freezing and H2O2 treatments. Cold pretreatment significantly enhanced the freezing tolerance of this species. The plants with higher CG content showed both lower MDA content and a lower percentage of injury under freezing stress. A marked decrease in CG level over a 72h freezing treatment in all experimental groups strongly indicated that CG was transformed and might play a key role against freezing stress. At the same time, plants with a higher level of CG also showed more superoxide dismutase (SOD) and catalase (CAT) activity. These results implied that the significant promotion of antioxidant capacity in this species might be associated with the remarkable accumulation of CG after cold pretreatment. Our results provided the first evidence that a type of isoflavonoid, CG, might play a very important role against freezing stress in vivo. This report also provides a basis for future studies to reveal the mechanisms of CG's role in freezing tolerance.