稀土尾矿构树根系形态及代谢研究

Response of Root Morphology and Root Metabolic of Broussonetia papyrifera to Rare Earth Tailings

为揭示构树对稀土尾矿生境的适应机制,选取赣南稀土矿区为对象,对比分析开采后尾矿修复区和对照区(未开采地段)构树根系形态特征和根系代谢产物的异同。结果表明,与对照相比,根系长度、表面积和生物量均减少,但直径<1 mm的侧根根长和表面积所占比例提高;总比根长和比表面积呈增加趋势,其中直径<1 mm的根系增幅最大,比根长增加109.58%,比表面积增加81.91%。通过LC-MS分析检测到1 968种代谢产物发生显著变化,1 812种物质上调,156种下调表达。经聚类和OPLS—DA分析,发现46种代谢物对构树应对稀土尾矿环境压力起了实质性的贡献,其中色氨酸、酪氨酸、苏氨酸、丝氨酸等氨基酸类物质,松三糖、核糖、麦芽糖、海藻糖、木二糖、葡萄糖、甘露糖等糖类物质具有重要渗透调节作用,而3-脱氢莽草酸酯、谷胱甘肽、泛酸、白藜芦醇、芝麻素、胡萝卜素等代谢物显著上调,为重要的抗氧化物质,基于OPLS-DA模型筛选的VIP值最大的差异代谢物葫芦巴碱可能一方面作为渗透调节物质保护着细胞膜,另一方面调控着根系的生长。可见,构树能够通过根系形态上的调整和根系代谢的响应适应稀土尾矿土壤环境。

In order to reveal the resistance mechanism of Broussonetia papyrifera,a phytoremediation experiment was carried out in the rare earth tailings in southern Jiangxi Province to study the morphological characteristics and the metabolites of the root system.The results showed that the root length,surface area and biomass reduced compared with the control,while the length and surface area of lateral root,which was less than1mm diameter,increased.The total specific root length and specific surface area showed increasing trends,especially,the root less than1mm had the largest increase of which the specific root length increased by109.58%and the specific surface area increased by81.91%.The metabolites of1968species changed significantly via LC-MS analysis with the up-regulation of1,812species and the down-regulation of156species.By clustering and OPLS-DA model analysis,46kinds of metabolites of B.papyrifera substantially attributed to environmental stress of the rare earth tailings.Differential metabolites including amino acids material such as tryptophan,tyrosine,threonine,serine and carbohydrates such as melezitos,ribose,maltose,trehalose,Xylobiose,glucose,mannose played an important role in osmoregulation.While other differential metabolites,which were important antioxidant compounds,rose significantly,such as3-dehydroshikimate,glutathione,pantothenic acid,resveratrol,sesamin,carotene.The most differential metabolite of VIP,hulubasine,may protect the cell membrane as an osmotic regulator on the one hand and regulate the growth of the root system on the other.Thus,B.papyrifera can adapt to the rare earth tailing environment through the adjustment of root morphology and the response of root metabolism.