新疆艾比湖胡杨凋落物与裸斑土壤代谢物差异比较

在干旱区荒漠胡杨疏林中，胡杨冠下存在草本植物极其稀疏的裸露斑块(简称裸斑)。为研究胡杨冠下裸斑形成化感机理，以裸斑内、外土壤以及冠下凋落物为研究对象，利用液相色谱-质谱联用技术对不同样本进行代谢组分析，使用PLS-DA鉴定并筛选各组代谢物差异，筛选出裸斑内、外土壤样本中差异显著的代谢物质及其代谢相关通路。研究结果显示，土壤样品中共鉴定出总代谢物质908种(615正，293负);凋落物样品中共鉴定出总代谢物质1291种(760正，531负)。通过筛选、注释并分类各组间差异显著的代谢物发现曲酸、微囊藻毒素、茶碱、辛二酸、花生四烯酸以及反式肉桂酸等化感物质相对定量值均为裸斑内显著大于裸斑外土壤；儿茶素、咖啡酸、吲哚、棕榈油酸、孜然醛、阿魏酸、反式肉桂酸、花生四烯酸、水杨醇以及香豆素等化感物质相对定量值均为凋落物样中显著大于土壤样品。以上胡杨潜在化感物质的积累可能增强植物的化感效应，导致胡杨冠下草本植物种子萌发及生长受到限制。

Comparison of soil metabolite differences between litter of Populus euphratica and bare spots in Ebinur Lake area, Xinjiang

The herbaceous plants are rare under the crown of the natural Populus euphratica stands (referred to as bare spots) in the arid Populus euphratica sparse forest area. To study the allelopathic formation mechanism of the bare spots under the Populus euphratica canopy, the soil inside and outside the bare spots and the litter under the canopy were used as the research objects in Ebinur Lake. We analyzed metabolomes of different samples using LC-MS technology, used PLS-DA to identify and screen metabolite differences in each group, and screened out significant differences in metabolites and their metabolic pathways in soil samples inside and outside of the bare spots. The results of the study showed that 908 total metabolites (615 positive and 293 negative) were identified in soil samples; a total of 1,291 total metabolites (760 positive and 531 negative) were identified in litter samples. By annotation and classification, it is found that the relatively quantitative values of allelochemicals such as Kojic acid, Microcystin, Theophylline, Suberic acid, Arachidonic acid and Trans-cinnamic acid were significantly higher in the bare spot than that in the soil under the tree canopy; In litter samples the relative quantitative values of allelochemicals such as Catechin, Caffeic acid, Indole, Palmitoleic acid, Cumin aldehyde, Ferulic acid, Trans-cinnamic acid, Arachidonic acid, Salicylic alcohol and Coumarin were significantly higher than that in soil samples. The accumulation of the above potential allelopathic substances in soil under Populus euphratica canopy and its litter may enhance the allelopathic effect of plants, leading to restrictions on the germination and growth of herb seeds under the Populus euphratica canopy.