异裂菊属根际微生物群落结构及功能多样性

Structural and functional diversity of rhizosphere microbial community of Heteroplex

关键词:  喀斯特石山区, 特有属, 根际微生物, PCR-DGGE, Biolog微平板法

Key words:  karst limestone regions, endemic genus, rhizosphere microbial community, PCR-DGGE, Biolog-Eco

摘要:

异裂菊属是广西喀斯特石山区典型的特有属,根际微生物是其能否有效吸收、有效利用土壤养分和适应石山恶劣土壤环境的最直接表征之一。该研究采用DGGE和Biolog两种方法对异裂菊属植物根际和非根际微生物多样性进行了研究。结果表明:(1)异裂菊属5个种根际pH、碱解氮等9个养分含量都高于非根际。(2)5个种的根际、非根际存在2个共有细菌类群,但在数量上存在差异,3个种的根际条带小于非根际; 5个种的根际、非根际微生物群落较为相似,较易聚在一起。(3)绢叶异裂菊根际微生物对碳源利用能力最强,凹脉异裂菊非根际最弱,其他对碳源的利用能力较接近; 异裂菊属种根际微生物利用碳源的能力都高于非根际,根际微生物多样性指数均高于非根际,优势度指数与非根际基本相同或略高于非根际,丰富度和均匀度指数与优势度指数规律相似; 异裂菊属根际、非根际微生物利用的碳源主要是糖类、羧酸类和氨基酸类化合物,4个种根际微生物利用碳源的能力高于非根际。(4)阳离子交换量、黏粒含量百分率和碱解氮是影响异裂菊属根际微生物碳源利用模式的最重要因子。总体来说,土壤理化性质对异裂菊属植物根际微生物群落多样性具有重要影响,异裂菊属通过分泌羧酸、糖等多类化合物提高了根际微生物的活性,进而有效地提高了根际肥力水平。

Abstract:

Heteroplex is a typical endemic genus of karst rocky mountainous area in Guangxi, and rhizosphere microorganism is one of the most direct representations of its ability to absorb and utilize soil nutrients and adapt to the harsh soil environment. In this study, DGGE and Biolog methods were used to study the rhizosphere and non-rhizosphere microbial diversity of Heteroplex. The results showed that the values of pH and alkali nitrogen content in the rhizosphere were hi-gher than those in the non-rhizosphere. The results of DGGE showed that two common bacterial groups were same in the rhizosphere and non-rhizosphere of Heteroplex, but the numbers were different. The bands in DGGE profile of the three species were less than non-rhizosphere. Rhizosphere and non-rhizosphere microbial community of each species were similar. The results of Biolog showed that the rhizosphere microorganisms of H. sericophylla had the strongest ability to use carbon source, and the non-rhizosphere of H. impressinervia was the weakest, and the ability of utilize carbon source of other rhizosphere and non-rhizosphere microbial community was close. The microbial diversity index of rhizosphere microorganisms was higher than that of non-rhizosphere, and the dominance index was the same as that of non-rhizosphere, the richness and evenness index are similar to the dominance index. The carbon sources used in non-rhizosphere microbes were mainly sugars, carboxylic acids and amino acids. The ability of utilize carbon source of four rhizosphere microorganisms were higher than non-rhizosphere. Cation exchange capacity, clay content and alkali nitrogen were the most important factors affecting the microbial carbon source utilization model of rhizosphere microorganisms. In general, the soil physical and chemical properties have an important effect on rhizosphere microbial community diversity of Heteroplex, and the activity of the rhizosphere microorganisms and fertility level were improved by secreting compounds such as carboxylic acid and sugar.