Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha, 410205, Hunan, People's Republic of China.
Sci Rep. 2020 Nov 23;10(1):20408. doi: 10.1038/s41598-020-77475-3.
Continuous cropping lowers the production and quality of ramie (Boehmeria nivea L. Gaud). This study aimed to reveal the metagenomic and metabolomic changes between the healthy- and obstacle-plant after a long period of continuous cropping. After 10 years of continuous cropping, ramie planted in some portions of the land exhibited weak growth and low yield (Obstacle-group), whereas, ramie planted in the other portion of the land grew healthy (Health-group). We collected rhizosphere soil and root samples from which measurements of soil chemical and plant physiochemical properties were taken. All samples were subjected to non-targeted gas chromatograph-mass spectrometer (GS/MS) metabolome analysis. Further, metagenomics was performed to analyze the functional genes in rhizospheric soil organisms. Based on the findings, ramie in Obstacle-group were characterized by shorter plant height, smaller stem diameter, and lower fiber production than that in Health-group. Besides, the Obstacle-group showed a lower relative abundance of Rhizobiaceae, Lysobacter antibioticus, and Bradyrhizobium japonicum, but a higher relative abundance of Azospirillum lipoferum and A. brasilense compared to the Health-group. Metabolomic analysis results implicated cysteinylglycine (Cys-Gly), uracil, malonate, and glycerol as the key differential metabolites between the Health- and Obstacle-group. Notably, this work revealed that bacteria such as Rhizobia potentially synthesize IAA and are likely to reduce the biotic stress of ramie. L. antibioticus also exerts a positive effect on plants in the fight against biotic stress and is mediated by metabolites including orthophosphate, uracil, and Cys-Gly, which may serve as markers for disease risk. These bacterial effects can play a key role in plant resistance to biotic stress via metabolic and methionine metabolism pathways.
连作对苎麻（Boehmeria nivea L. Gaud）的产量和品质有降低作用。本研究旨在揭示长期连作后健康植株和障碍植株之间的宏基因组和代谢组变化。在连续种植 10 年后，部分土地上种植的苎麻生长较弱，产量较低（障碍组），而另一部分土地上种植的苎麻生长健康（健康组）。我们采集了根际土壤和根系样本，对土壤化学和植物生理化学性质进行了测量。所有样本均进行了非靶向气相色谱-质谱（GS/MS）代谢组分析。此外，还进行了宏基因组学分析，以分析根际土壤生物中的功能基因。基于研究结果，与健康组相比，障碍组的苎麻表现出植株矮小、茎径小、纤维产量低的特征。此外，障碍组的根瘤菌科、Lysobacter antibioticus 和 Bradyrhizobium japonicum 的相对丰度较低，而 Azospirillum lipoferum 和 A. brasilense 的相对丰度较高。代谢组学分析结果表明，胱氨酸甘氨酸（Cys-Gly）、尿嘧啶、丙二酸和甘油是健康组和障碍组之间的关键差异代谢物。值得注意的是，本研究表明，根瘤菌等细菌可能合成 IAA，从而降低苎麻的生物胁迫。L. antibioticus 对植物也有积极的抗生物胁迫作用，其作用机制是通过代谢物包括正磷酸盐、尿嘧啶和 Cys-Gly 介导的，这些代谢物可能作为疾病风险的标志物。这些细菌作用可能通过代谢和蛋氨酸代谢途径在植物对生物胁迫的抗性中发挥关键作用。
