两种镉积累型小麦根际微生物群落结构及功能多样性

为探究不同积累型小麦品种对根际微生物群落结构及功能多样性的影响，以镉低积累型小麦济麦22和镉高积累型小麦冀5265为研究材料，采用分离培养法和Biolog-Eco微平板法分析根际细菌数量、可培养优势群落结构以及微生物群落功能多样性。结果表明：污染土壤济麦22根际总细菌数量和抗Cd细菌数量均显著高于冀5265,而非污染土壤中两品种间无差异。污染土济麦22根际发现较多产脲酶和高镉抗性菌株(200 mg/L)。污染土济麦22根际优势菌多为Arthrobacter sp.和Bacillus sp.,冀5265根际优势菌主要为Streptomyces sp.;非污染土济麦22与冀5265根际优势菌群相似，均以Bacillus sp.为主。Biolog试验结果表明，两个小麦品种根际微生物群落对碳源的利用能力存在差异，济麦22根际微生物AWCD值、Mc Intosh指数、Shannon-Wiener指数、Simpson指数在污染土和无污染土中均显著高于冀5265。因此，污染土壤中不同积累型小麦品种根际微生物群落结构及功能多样性均存在差异，该研究结果对于揭示高低积累型小麦根际微生物机制提供了重要参考依...

Rhizosphere microbial community structure and functional diversity in two Cd-accumulating wheat cultivars

In order to investigate the effects of the different accumulating wheat cultivars on rhizosphere microorganism community structure and functional diversity, low Cd-accumulating wheat Jimai 22 (JM22) and high Cd-accumulating wheat Ji 5265 (JI5265) were planted in pots filled with contaminated soil and non-contaminated soil and collected at the tillering stage of wheat. In total, four experimental treatments were set up, containing JM22 grown in contaminated soil (CJM), JI5265 grown in contaminated soil (CJI), JM22 grown in non-contaminated soil (NJM) and JI5265 grown in non-contaminated soil (NJI). The number of rhizosphere bacteria, community structure of culturable dominant bacteria and microbial community functional diversity were analyzed by traditional dilution plate culture method and Biolog-Eco microplate method. The results from the standard spread-plate method showed that the population of total bacteria and Cd-resistant bacteria in rhizosphere soil of JM22 were significantly higher than those of JI5265 in contaminated soil, but there was no significant difference in the population of total bacteria and Cd-resistant bacteria of rhizosphere soil between the two different accumulating wheat cultivars in non-contaminated soil. Studies on the biological characteristics of the isolated strains showed that more urease producing bacterial strains and Cd-resistant bacterial strains (200 mg/L) in rhizosphere soil of JM22 grown in contaminated soil were isolated than those of JI5265 grown in contaminated soil. Based on 16S rRNA gene sequences analysis, bacterial community composition was different in rhizosphere soil between cultivar JM22 and cultivar JI5265 in contaminated soil. Most of the dominant rhizosphere bacteria in JM22 were identified as Arthrobacter sp. and Bacillus sp., while Streptomyces sp. predominated in rhizosphere soil of wheat JI5265 in contaminated soil. The dominant rhizosphere bacteria in JM22 and JI5265 grown in non-contaminated soil were similar, and they were mainly Bacillus sp. The Biolog-Eco plate experiment results showed that there were differences in the utilization of carbon sources between the two wheat cultivars, and the average well color development (AWCD) values, Mc Intosh index, Shannon-Wiener index and Simpson index of rhizosphere microbes of wheat cultivar JM22 were significantly higher than those of cultivar JI5265 in both contaminated soil and non-contaminated soil after 120 h of incubation. Taken together, the community structure and functional diversity of rhizosphere microorganisms in the two Cd-accumulating wheat cultivars grown in contaminated soil were different. The results provide an important reference for understanding the rhizosphere microbial mechanism in high and low accumulating wheats.