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植物代谢组学案例分析

植物组学大豆幼苗叶片对盐胁迫的响应

 

研究对象:大豆

分析检测平台:GC-TOF/MS (BIOTREE)

期刊:PLoS ONE

影响因子:3.057

发表时间:2016

 

摘要:

Clarification of the metabolic mechanisms underlying salt stress responses in plants will allow further optimization of crop breeding and cultivation to obtain high yields in salinealkali land. Here, we characterized 68 differential metabolites of cultivated soybean (Glycine max) and wild soybean (Glycine soja) under neutral-salt and alkali-salt stresses using gas chromatography-mass spectrometry (GC-MS)-based metabolomics, to reveal the physiological

and molecular differences in salt tolerance. According to comparisons of growth parameters under the two kinds of salt stresses, the level of inhibition in wild soybean was lower than in cultivated soybean, especially under alkali-salt stress. Moreover, wild soybean contained significantly higher amounts of phenylalanine, asparagine, citraconic acid, citramalic acid, citric acid and α-ketoglutaric acid under neutral-salt stress, and higher amounts of palmitic acid, lignoceric acid, glucose, citric acid and α-ketoglutaric acid under alkali-salt stress, than cultivated soybean. Further investigations demonstrated that the ability of wild soybean to salt tolerance was mainly based on the synthesis of organic and amino acids, and the more active tricarboxylic acid cycle under neutral-salt stress. In addition, the metabolite profiling analysis suggested that the energy generation from β-oxidation, glycolysis and the citric acid cycle plays important roles under alkali-salt stress. Our results extend the understanding of mechanisms involved in wild soybean salt tolerance and provide an important reference for increasing yields and developing salt-tolerant soybean cultivars.

 

一、研究背景:

大豆是重要的重要的经济和油料作物,然而培育过程中其耐盐能力逐渐下降,严重影响植株生长和产品质量。野生大豆与培育大豆亲缘关系紧密,但常表现出更强的耐盐能力。通过对野生株研究,Na+、抗氧化酶和次级代谢途径等在植株不同部位的表达均对耐盐过程有影响。在应激过程中,野生株中有更高的氨基酸、二糖类物质积累,而不饱和脂肪酸、羧酸和单糖类物质低于培育植物。代谢物组学可更全面揭示植株对环境的响应过程,包括植物机能、代谢网络、代谢调控机制和表型等均可通过对代谢物的考察进行研究。此前代谢组学这一研究工具在植物应激过程的分析研究中已得到广泛使用。本文尝试从耐受能力不同的植株出发,尝试通过比较发现大豆耐盐能力相关代谢途径并为后续代谢工程改造提供基础。

 

二、方法流程:

 

 

三、研究结果与讨论:

1 生长状态的区别

1)W(野生株)在盐压力或盐碱压力下生长状态明显优于M(培育株)

2)盐碱压力比中性盐压力造成更严重的生长下降

 

 

图1不同植株在盐碱压力下的生长表现

 

2 大豆在不同条件下的代谢物组差异分析

1)主成分分析(PCA)表明植株在不同条件下的代谢物出现整体变化;

2)正常条件:W中TCA循环和产能途径活跃,M中氨基酸等合成较活跃;

3)盐压力:W中TCA循环、有机酸和氨基酸合成加强

4)盐碱压力:W中硬脂酸、壬酸、木蜡酸出现积累,M中下降;W中糖酵解和TCA循环加强,M中减弱。

 

图2 多元变量统计分析建立PCA A模型的得分图和上样图

 

3 野生大豆在盐碱压力下的耐受机制

1)通过积累小分子代谢物,如有机酸、氨基酸等降低胞质内水势;

2)通过信号分子,如水杨酸(SA)、鲨烯等,激活抗氧化途径,降低细胞膜脂质过氧化程度;

3)盐压力:W中TCA循环、有机酸、氨基酸和脂肪酸合成加强

 

四、亮点和展望:

l 通过设置不同强度盐压力条件,考察野生大豆W耐受株)逐级递增的应激策略。

l 通过与培育大豆M敏感株)比较,排除与耐受能力不相关的代谢变化,获得关键响应途径

l 通过代谢组学分析提出野生大豆的应激策略:提高相容性溶质积累量和产能途径活性;

l 展望:可将已发现的耐受性相关途径与转录组学、蛋白组学结合考察,确定关键的应激响应途径

l 展望:代谢组学发现了相对宏观的盐碱耐受机制,还需通过对关键基因的考察获得更具体的代谢工程改造靶点

 

阅读文献下载地址:

Zhang J, Yang D, Li M, et al. Metabolic Profiles Reveal Changes in Wild and Cultivated Soybean Seedling Leaves under Salt Stress:[J]. Plos One, 2016, 11(7).