School of Life Sciences, Xinjiang Normal University, Urumqi, China.
Microb Ecol. 2013 Aug;66(2):385-93. doi: 10.1007/s00248-012-0160-5. Epub 2013 Jan 9.
The purpose of this study was to examine the variations in the microbial community structure of soil actinomycetes in fields with continuous cropping of cotton in Xinjiang Autonomous Region, China. Soil samples were collected from four depths in fields with 7-year continuous cotton cropping. The community structure of soil actinomycetes was examined using the 16S rRNA-based polymerase chain reaction-density gradient gel electrophoresis (PCR-DGGE) techniques. The microbial diversity indices of the soil samples from different depths generally decreased along with the period of continuous cotton cropping. When the period of continuous cropping of cotton reached 5 years, the diversity indices rose again and gradually stabilized at a level slightly lower than that of soils with original ecology (i.e., 0-year cotton cropping). Cluster analysis showed that at the 1-20-cm depth, the actinomycete community structure of the soil subjected to 1-year cotton cropping was similar to that of soil subjected to 0-year cotton cropping, whereas that of soils after 3-year continuous cotton cropping showed high similarity. At the 21-40-cm depth, the actinomycete community structure showed various changes but generally recovered to its original pattern after repeated fluctuations. Principal component analysis showed that at the 1-30-cm depth, the actinomycete community structure varied similarly regardless of the period of continuous cotton cropping. In contrast, there were no clear actinomycete community structure variation trends at the 31-40-cm soil depth. Homology comparison of sequences recovered from the DGGE bands showed that the obtained sequences shared similarities >88 %. Alignment with the known homologous sequences indicated a lack of microorganisms related to soil-borne cotton diseases. Continuous cotton cropping exerted significant influences on the community structure of soil actinomycetes in Xinjiang Autonomous Region, which were largely determined by the soil depth and the period of continuous cotton cropping. The microbial diversity of soil actinomycete communities gradually recovered after 5-year continuous cropping. Thereafter, a new actinomycete community structure that was beneficial for continuous cropping of cotton was formed and stabilized each year.
本研究旨在考察中国新疆地区棉花连作田土壤放线菌微生物群落结构的变化。从连续种植棉花 7 年的田块中采集了 4 个深度的土壤样本。采用基于 16S rRNA 的聚合酶链反应-密度梯度凝胶电泳（PCR-DGGE）技术检测土壤放线菌的群落结构。不同深度土壤样本的微生物多样性指数随连续棉花种植时间的延长而普遍下降。当棉花连续种植时间达到 5 年时，多样性指数再次上升，并逐渐稳定在略低于原始生态土壤（即棉花种植 0 年）的水平。聚类分析表明，在 1-20cm 深度，种植 1 年棉花的土壤放线菌群落结构与种植 0 年棉花的土壤相似，而连续种植 3 年的土壤相似性较高。在 21-40cm 深度，放线菌群落结构变化多样，但在反复波动后总体恢复到原有模式。主成分分析表明，在 1-30cm 深度，放线菌群落结构无论连续棉花种植时间如何变化都相似。相比之下，在 31-40cm 土壤深度，没有明显的放线菌群落结构变化趋势。从 DGGE 条带中回收的序列的同源性比较表明，获得的序列相似度>88%。与已知同源序列的比对表明，缺乏与土传棉花病害相关的微生物。连续棉花种植对新疆地区土壤放线菌群落结构产生了显著影响，主要由土壤深度和连续棉花种植时间决定。在连续种植 5 年后，土壤放线菌群落的微生物多样性逐渐恢复。此后，每年都会形成并稳定一个有利于棉花连作的新放线菌群落结构。
