Microbial metabolic efficiency functions as a mediator to regulate rhizosphere priming effects
Microbial metabolic efficiency functions as a mediator to regulate rhizosphere priming effects
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微生物代谢效率作为调节根际启动效应的介质
DOI：
10.1016/j.scitotenv.2020.143488
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发表时间：
2021
影响因子：
9.8
通讯作者：
Jingping Yang
中科院分区：
文献类型：
--
作者：
Chaoyang Mo;Zhenhui Jiang;Pengfei Chen;Hao Cui;Jingping Yang
微生物代谢效率（MME）是反映碳在微生物生长中分配的重要生理指标，是调控土壤系统启动效应的重要途径之一。然而，MME在植物-土壤系统中调控根际引发效应（RPE）的功能和机制尚不清楚。本研究采用盆栽试验方法，在水稻土和土两种土壤类型、高粱[Sorcium bicolor（L.）Moench]和玉米[Zea maysL.]）和三个生长阶段（大喇叭口期、开花期和成熟期），以探讨RPE的MME机制。在大喇叭期，RPE呈阳性（高达76%），在成熟期，RPE呈阴性（降至-11%）。相关酶活性和微生物生物量的变化表明，“微生物活化”和“微生物氮（N）开采”的假设一起发挥作用。“优先底物利用”假说则在后两个阶段发挥作用。在此基础上，通过相关性分析，引入MME调节RPE：土壤C、N的有效性和微生物生物量共同形成微生物C：N失衡（MIC：N），微生物根据MIC：N调节自身MME，从而调节RPE。具体而言，在所有种植处理中，由较高MIC：N诱导的较低MME负责大喇叭期的较大RPE，而由较低MIC：N诱导的较高MME负责开花和成熟期的较低或负RPE。综上所述，MIC：N形成的MME在种植土壤中起着调节RPE的中介作用。
Microbial metabolic efficiency (MME), a key physiological property that indicates the allocation of carbon (C) to microbial growth, is surely one potential pathway involved in the regulation of priming effect within soil systems. However, the function and mechanism concerning the regulation of the rhizosphere priming effects (RPE) by MME in plant-soil systems remain unclear. In this study, we performed a pot experiment that included two soil types (paddy soil and lou soil), two plant species (sorghum [Sorghum bicolor(L.) Moench] and maize [Zea maysL.]) and three stages of growth (big trumpet, blooming and mature stage) to investigate the MME mechanism of RPE. Both positive (up to 76% at the big trumpet stage) and negative (down to −11% at the mature stage) RPE were observed. A shift in related enzyme activities and microbial biomass indicated that the ‘microbial activation’ and ‘microbial nitrogen (N) mining’ hypotheses functioned together at first. The ‘preferential substrate utilization’ hypothesis then functioned at the latter two stages. After that, according to a correlation analysis method, the MME was introduced to regulate the RPE: the availability of soil C and N and the microbial biomass jointly shaped the microbial C: N imbalance (MIC:N), and the microbes then regulated their MME based on the MIC:N, thus, regulating the RPE. Specifically, the lower MME induced by a higher MIC:Nwas responsible for a greater RPE at the big trumpet stage across all the planted treatments, while a higher MME induced by a lower MIC:Nwas responsible for the lower or negative RPE at the blooming and mature stages. Overall, these findings demonstrate that the MME shaped by MIC:Nfunctions as a mediator to regulate the RPE in planted soil.