镉胁迫下丛枝菌根真菌对彩叶草生理代谢和根系损伤的影响

Arbuscular mycorrhizal fungi improve physiological metabolism and ameliorate root damage of Coleus scutellarioides under cadmium stress

摘要:

土壤镉污染会对观赏植物彩叶草的种植造成不利影响，当土壤受到镉污染时，彩叶草的发育会受阻，甚至可能因镉的毒性积累而死亡。本研究以金边彩叶草为实验植物，摩西斗管囊霉为供试菌，通过测定彩叶草的生理代谢和根系损伤程度，探究丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)对彩叶草适应镉胁迫的影响。结果表明，镉胁迫致使彩叶草细胞内超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(ceroxidase,POD)以及过氧化氢酶(catalase,CAT)的活性、丙二醛(malondialdehyde,MDA)和脯氨酸(proline,Pro)含量上升，菌根侵染率、根系活力则受到不同程度的抑制，生长速率减慢。相同镉浓度下，接种AMF显著改善了彩叶草的各项生理指标，其中MDA含量最大降幅为42.16%，次生代谢产物迷迭香酸和花色素苷的含量最多可分别增长27.43%和25.72%，根系活力增幅高达35.35%，根系DNA损伤得到明显修复。综上所述，通过接种AMF可促进彩叶草次生代谢产物积累，缓解根系损伤，增强其对镉胁迫的耐受性。

Abstract:

Soil cadmium pollution can adversely affect the cultivation of the ornamental plant, Coleus scutellarioides. Upon cadmium contamination of the soil, the growth of C. scutellarioides is impeded, and it may even succumb to the toxic accumulation of cadmium. In this study, we investigated the effects of arbuscular mycorrhizal fungi (AMF) on the adaptation of C. scutellarioides to cadmium stress, by measuring the physiological metabolism and the degree of root damage of C. scutellarioides, with Aspergillus oryzae as the test fungi. The results indicated that cadmium stress increased the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the content of malondialdehyde (MDA) and proline (Pro) within the cells of C. scutellarioides, but inhibited mycorrhizal infestation rate, root vigour and growth rate to a great degree. With the same cadmium concentration, the inoculation of AMF significantly improved the physiological indexes of C. scutellarioides. The maximum decrease of MDA content was 42.16%, and the content of secondary metabolites rosemarinic acid and anthocyanosides could be increased by up to 27.43% and 25.72%, respectively. Meanwhile, the increase of root vigour was as high as 35.35%, and the DNA damage of the root system was obviously repaired. In conclusion, the inoculation of AMF can promote the accumulation of secondary metabolites, alleviate root damage, and enhance the tolerance to cadmium stress in C. scutellarioides.