Pump Judith, Pratscher Jennifer, Conrad Ralf
Department of Biogeochemistry, Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043, Marburg, Germany.
Environ Microbiol. 2015 Jul;17(7):2254-60. doi: 10.1111/1462-2920.12675. Epub 2015 Jan 27.
The methane emitted from rice fields originates to a large part (up to 60%) from plant photosynthesis and is formed on the rice roots by methanogenic archaea. To investigate to which extent root colonization controls methane (CH4 ) emission, we pulse-labeled rice microcosms with (13) CO2 to determine the rates of (13) CH4 emission exclusively derived from photosynthates. We also measured emission of total CH4 ((12+13) CH4 ), which was largely produced in the soil. The total abundances of archaea and methanogens on the roots and in the soil were analysed by quantitative polymerase chain reaction of the archaeal 16S rRNA gene and the mcrA gene coding for a subunit of the methyl coenzyme M reductase respectively. The composition of archaeal and methanogenic communities was determined with terminal restriction fragment length polymorphism (T-RFLP). During the vegetative growth stages, emission rates of (13) CH4 linearly increased with the abundance of methanogenic archaea on the roots and then decreased during the last plant growth stage. Rates of (13) CH4 emission and the abundance of methanogenic archaea were lower when the rice was grown in quartz-vermiculite with only 10% rice soil. Rates of total CH4 emission were not systematically related to the abundance of methanogenic archaea in soil plus roots. The composition of the archaeal communities was similar under all conditions; however, the analysis of mcrA genes indicated that the methanogens differed between the soil and root. Our results support the hypothesis that rates of photosynthesis-driven CH4 emission are limited by the abundance of methanogens on the roots.
稻田排放的甲烷很大一部分（高达60%）源自植物光合作用，由产甲烷古菌在水稻根系上形成。为了研究根系定殖在多大程度上控制甲烷（CH4）排放，我们用（13）CO2对水稻微观生态系统进行脉冲标记，以确定仅源自光合产物的（13）CH4排放速率。我们还测量了总CH4（（12 + 13）CH4）的排放，其主要在土壤中产生。分别通过对古菌16S rRNA基因和编码甲基辅酶M还原酶亚基的mcrA基因进行定量聚合酶链反应，分析了根系和土壤中古菌和产甲烷菌的总丰度。用末端限制性片段长度多态性（T-RFLP）确定古菌和产甲烷菌群落的组成。在营养生长阶段，（13）CH4排放速率随根系上产甲烷古菌的丰度呈线性增加，然后在植物生长的最后阶段下降。当水稻种植在仅含10%稻田土的石英 - 蛭石中时，（13）CH4排放速率和产甲烷古菌的丰度较低。总CH4排放速率与土壤加根系中产甲烷古菌的丰度没有系统关联。在所有条件下，古菌群落的组成相似；然而，对mcrA基因的分析表明，土壤和根系中的产甲烷菌不同。我们的结果支持以下假设：光合作用驱动的CH4排放速率受根系上产甲烷菌丰度的限制。
