The circadian clock mediates metabolic functions of plants and rhythmically shapes structure and function of microbial communities in the rhizosphere. However, it is unclear how the circadian rhythm of plant hosts regulates changes in rhizosphere bacterial and fungal communities and nutrient cycles. In the present study, we measured diel changes in the rhizosphere of bacterial and fungal communities, and in nitrogen (N) and phosphorus (P) cycling in 20-year-old tea plantations. The fungal communities were more stable in their responses to circadian changes than bacterial communities in the rhizosphere of the variants LJ43 and ZC108. Nevertheless, fungal genera with circadian rhythms were more numerous and had a higher abundance at midnight. Organic P and N mineralization in the rhizosphere was more intensive in LJ43 under day-night alterations, while inorganic N and P cycling were more easily affected by circadian rhythms in ZC108. The rhizosphere denitrification encoded by the genes AOA and AOB was intensive in the morning, irrespective of tea species. Genes related to rhizosphere N fixation (nifH) and denitrification (nosZ and nirK) expressed at greater levels in ZC108, and they reached a peak at midnight. Moreover, the diel rhythm of rhizosphere microbial communities in ZC108 largely regulated dial changes in N and P cycling. These results suggested that the bacterial and fungal communities in the rhizosphere respond differently to circadian rhythms, and they vary between tea species. The timing of bacterial and fungal cycling largely regulates rhizosphere N and P cycling and their ecological functions.

中文翻译：

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微生物群落的昼夜节律及其在调节茶树根际氮磷循环中的作用


生物钟介导植物的代谢功能，并有节奏地塑造根际微生物群落的结构和功能。然而，目前尚不清楚植物宿主的昼夜节律如何调节根际细菌和真菌群落以及营养循环的变化。在本研究中，我们测量了细菌和真菌群落根际的 diel 变化，以及 20 年历史茶园中氮 （N） 和磷 （P） 循环的变化。真菌群落对昼夜节律变化的反应比变体 LJ43 和 ZC108 根际的细菌群落更稳定。尽管如此，具有昼夜节律的真菌属数量更多，午夜时分的丰度更高。在昼夜变化下，LJ43 根际有机 P 和 N 矿化更强烈，而 ZC108 中无机 N 和 P 循环更容易受到昼夜节律的影响。由 AOA 和 AOB 基因编码的根际反硝化作用在早晨很密集，与茶种类无关。与根际 N 固定 （nifH） 和反硝化 （nosZ 和 nirK） 相关的基因在 ZC108 中表达水平较高，并在午夜达到峰值。此外，ZC108 中根际微生物群落的 diel 节律在很大程度上调节了 N 和 P 循环的表盘变化。这些结果表明，根际的细菌和真菌群落对昼夜节律的反应不同，并且它们因茶种而异。细菌和真菌循环的时间在很大程度上调节根际 N 和 P 循环及其生态功能。