芦苇群落水体质量与芦苇转录本的相关性

Research on correlation between water quality and transcripts in Phragmites australis

芦苇(Phragmites australis)是广生态幅多年生水生植物,在全球分布极广。芦苇能够适应并生长在极端环境,如盐碱地、重金属污染地等,这种巨大的环境忍耐能力使得芦苇成为研究植物环境适应性的模式物种,并逐渐成为植物学和生态学等领域的研究热点。目前,北京自然和人工湿地中大量栽植芦苇,其主要功能是净化水体、稳定水体自净能力。为深入了解水体质量对芦苇转录本的影响及二者之间的相关性,首先对北京及河北白洋淀共计32个采样点的8项水质指标进行了检测。结果表明,32个采样点的水体整体处于污染状态,主要污染物为总氮(TN)和生物需氧量(BOD),并且水质均略偏碱性,且具有高氮(N)、高磷(P)、高BOD和高化学需氧量(COD)等特征。主成分分析(PCA)表明8项水质指标间具有相关性,可被降至3个维度,第一维度是BOD/COD/高锰酸盐指数(CODMn);第二维度是TN/氨氮(NH3-N)/总磷(TP);第三维度是pH/溶解氧(DO)。对水质指标与芦苇叶片RNA-seq转录本进行皮尔森系数相关性分析,筛选出247个与水质指标相关的转录本。其中,232个基因(93.9%)的转录水平与水质指标呈现正相关性。经实验室单一因子或双因子验证确定了PB.4621.1(编码GMP合酶)和PB.12079.1(编码LEA14蛋白)两个基因更适合用于监测水体中的氮和磷水平。研究为后续芦苇监测水质技术的开发与利用奠定了理论基础。

Phragmites australis,as a wide-ranging perennial aquatic plant,is wildly spread in the worldwide.Phragmites australis has adapted to adverse terrestrial habitats such as saline meadow and heavy metal pollution,which makes it become a model species for studying plant environmental adaptability,and has become a research hotspot in the fields of botany and ecology,gradually.A large number of Phragmites australis had been planted in natural and artificial wetlands in Beijing used for removing water pollution.However,the mechanism of monitoring water quality by Phragmites australis has not been clearly studied.In this study,we investigated 8 major water quality indexes of 32 sampling sites distributed all over the major water systems in Beijing and Baiyangdian of Hebei.According to"China National Surface Water Environmental Quality Standard GB3838—2002",the 8 major water quality indexes include pH,dissolved oxygen(DO),total nitrogen(TN),ammonia nitrogen(NH3-N),total phosphorus(TP),biological oxygen demand(BOD),chemical oxygen demand(COD)and permanganate index(CODMn).The results showed that the pollution of 32 water samples were relatively severe.While,the contamination of 32 sampling water were able to be degraded by using microorganism.In addition,the water quality of sampling sites was slightly alkaline,and had the characteristics of high nitrogen(N),high phosphorus(P),high BOD and COD,which indicated that the contamination of sampling sites was extremely serious,and the major pollutants in water are TN and BOD.Principal component analysis(PCA)showed that the 8 water quality indexes could be divided into 3 dimensions,the first dimension was COD/BOD/CODMn;the second dimension was TN/NH3-N/TP;and the third dimension was pH/DO.The water quality indexes within each dimension had a high positive correlation.We further screened out 247 transcripts associated with water quality indexes(Pearson correlation coefficient,PCC≥±0.55)using Phragmites australis transcriptome data(RNA-seq data).Among them,most transcripts(93.9%)were positively correlated with the water quality indexes.The proteins encoded by 132 genes of Phragmites australis related to nitrogen and phosphorus pollution are mainly involved in photosynthesis and protein quality control systems,including protein folding,sorting and degradation;there are also proteins involved in transcription,as well as plant defense systems,signal transduction and lipid metabolism.In addition,there are a large number of unknown proteins.The proteins encoded by 89 genes of Phragmites australis related to organic matter pollution are mainly involved in protein synthesis process and the expression of detoxification genes for degradation of pollutants efficiently.Moreover,it was found that genes transcription and defense system were also response to organic matter pollution.In addition,there are a large number of unknown functional proteins involved.The combination of two genes,PB.4621.1(encoding GMP synthase)and PB.12079.1(encoding LEA14 protein),is expected to become a core member of genes for monitoring water quality(N and P levels).Overall,we analyzed the transcriptome changes of Phragmites australis leaves,in order to obtain monitoring genes that can reflect water quality,and to explore new ecological uses of Phragmites australis.This study laid the foundation for the subsequent development of monitoring technology for water quality by using Phragmites australis.