土生对齿藓在干旱胁迫下的次生代谢物及调控基因

Secondary metabolites and related genes in Didymodon vinealis under drought recovery stress

摘要:

【目的】土生对齿藓作为沙漠苔藓具有较强的生存能力。研究土生对齿藓在复水和干旱胁迫下代谢物的变化，代谢通路和基因，为深入探究沙漠藓类植物提供理论依据。【方法】利用生长状况一致的土生对齿藓分别进行复水和干旱处理，从 1~8 天的样品中进行代谢组和转录组测定。【结果】1） 主成分分析（Principal Component Analysis，PCA）和正交偏最小二乘法分析土生对齿藓代谢产物的差异显著。复水处理 4 天时的土生对齿藓的代谢产物种类和数量达到最大，与对照组差异值达 55；干旱 6 天样本的代谢产物差异值为 49. 178。复水处理下的上调代谢产物明显高于干旱胁迫的土生对齿藓代谢产物。2）复水处理下的高代谢产物分别是：4‐羟基苯乙酸、尿囊酸、甲基‐β‐D‐吡喃半乳糖苷、3‐氰丙氨酸、衣康酸、2‐氨基酚、乳酸、京都酚等。主要涉及的代谢途经分别是脂肪酸代谢、嘌呤代谢、萜类化合物代谢、非必须氨基酸代谢、酚类代谢和细胞降解代谢。其对应的功能基因有：ga1A，rafA，maLZ， hisB，E2. 7. 1. 138，CERK，E2. 4. 1. 46，GPD1，ACTF，GALM，ahcy，CALM，EEFIB，phnX，CPK， desA，crtZ 等。3）干旱胁迫处理后，表达量较高的代谢物是 2-单棕榈酸甘油酯、尿囊酸、熊果苷、胆甾烷‐3，5，6‐三醇、烯丙基丙二酸、泛酸等。主要涉及的代谢途经分别是免疫激酶代谢、色素代谢、胆固醇代谢 、碳代谢 、氨基酸生物合成 、ABC 转运蛋白和嘌呤代谢等 。 功能基因有 ：FAH，crtZ，SUR2， SCSDL，CYC，COX4，QCR7，UQCRB，galU，galF，UGP2，thiN，TPK1，SMARCC 等。【结论】复水和干旱胁迫处理的土生对齿藓均参与了乳糖代谢、萜类物质生物合成以及酚类物质生物合成等通路关键酶基因的差异表达，其关键酶基因分别是 ga1A，hisB，CERK，GPD1，ACTF，CPK。从不同复水和干旱胁迫处理的代谢产物分析，说明土生对齿藓不耐受水淹，但对干旱胁迫有极强的耐受性。

Abstract:

【Objective】Didymodon vinealis has a strong survival ability in desert. Study of the changes of metabolites，metabolic pathways and genes under hydration and drought stress provides theoretical basis for further study on drought tolerance of desert mosses.【Method】 Rehydratration and drought treatments were performed in the soil with the same growth status，and the metabolome and transcriptome were determined in the samples over a one to eight day period.【Result】 1） Principal component analysis （PCA） and orthogonal partial least square analysis showed significant differences in the metabolites of D. vinealis. The difference of metabolites over 4 days of rehydration treatment was the largest，and the difference value was 55. The difference value of metabolites in 6-day drought samples was 49. 178. The up‐regulated metabolites under rehydration treatment were significantly higher than those under drought stress. 2） The high metabolites under rehydration treatment were：4 ‐hydroxyphenylacetic acid，allantoin，methyl‐β‐D‐galactopyranoside，3‐cyanoalanine，itaconic acid，2‐aminophenol，lactic acid，Kyoto phenol，etc. The main metabolic pathways involved were fatty acid metabolism，purine metabolism，terpenoid metabolism，nonessential amino acid metabolism，purine metabolism，phenolic metabolism and cell degradation metabolism. Its corresponding functional genes are： ga1A，rafA，maLZ，hisB，E2. 7. 1. 138，CERK，E2. 4. 1. 46，GPD1，ACTF，GALM，ahcy， CALM，EEFIB，phnX，CPK，desA，crtZ，etc.（3） After drought stress treatment，the metabolites with higher expression were 2-monopalmitin，allantoin，arbutin，cholesteryl‐3，5，6‐triol，allylmalonic acid，pantothenic acid，etc. The main metabolic pathways involved are immune kinase metabolism，pigment metabolism，cholesterol metabolism，carbon metabolism，amino acid biosynthesis，ABC transporter and purine metabolism. Functional genes include FAH， crtZ，SUR2，SCSDL，CYC，COX4，QCR7，UQCRB，galU，galF，UGP2，thiN，TPK1，SMARCC and so on. 【Conclusion】 Both rehydration and drought stress treatments resulted in the differential expression of key enzyme genes in the pathways of lactose metabolism，terpenoid biosynthesis and phenolic biosynthesis. The key enzyme genes were ga1A，hisB，CERK，GPD1，ACTF，CPK. The analysis of metabolites under different rehydration and drought stress treatments showed that the soil was not tolerant to flooding，but had strong tolerance to drought stress.