Abstract：
Legume-based rotation is commonly recognized for its mitigation efficiency of greenhouse gas (GHG) emissions. However, variations in GHG emission-associated metabolic functions during the legume-vegetable rotation process remain largely uncharacterized. Accordingly, a soybean-radish rotation field experiment was designed to clarify the responses of microbial communities and their GHG emission-associated functional metabolism through metagenomics. The results showed that the contents of soil organic carbon and total phosphorus significantly decreased during the soybean-radish process (P < 0.05), while soil total potassium content and bacterial richness and diversity significantly increased (P < 0.05). Moreover, the predominant bacterial phyla varied, with a decrease in the relative abundance of Proteobacteria and an increase in the relative abundance of Acidobacteria, Gemmatimonadetes, and Chloroflexi. Metagenomics clarified that bacterial carbohydrate metabolism substantially increased during the rotation process, whereas formaldehyde assimilation, methanogenesis, nitrification, and dissimilatory nitrate reduction decreased (P < 0.05). Specifically, the expression of phosphate acetyltransferase (functional methanogenesis gene, pta) and nitrate reductase gamma subunit (functional dissimilatory nitrate reduction gene, narI) was inhibited, indicating of low methane production and nitrogen metabolism. Additionally, the partial least squares path model revealed that the Shannon diversity index was negatively correlated with methane and nitrogen metabolism (P < 0.01), further demonstrating that the response of the soil bacterial microbiome responses are closely linked with GHG-associated metabolism during the soybean-radish rotation process. Collectively, our findings shed light on the responses of soil microbial communities to functional metabolism associated with GHG emissions and provide important insights to mitigate GHG emissions during the rotational cropping of legumes and vegetables.
摘要：
基于豆类的轮换因其对温室气体（GHG）排放的缓解效率而受到普遍认可。然而,在豆类-蔬菜轮作过程中，温室气体排放相关代谢功能的变化在很大程度上仍未表征。因此，设计了大豆-萝卜轮作田间试验，以通过宏基因组学阐明微生物群落的反应及其与GHG排放相关的功能代谢。结果表明,大豆-萝卜过程中土壤有机碳和全磷含量显著降低(P<0.05)。土壤全钾含量、细菌丰富度和多样性显著增加(P<0.05)。此外，主要的细菌门各不相同，随着变形杆菌相对丰度的减少和酸杆菌相对丰度的增加，双子座,和氯氟。宏基因组学阐明，细菌碳水化合物代谢在旋转过程中大幅增加，而甲醛同化，产甲烷，硝化，异化硝酸盐还原率降低(P<0.05)。具体来说,磷酸乙酰转移酶的表达(功能性甲烷生成基因，pta)和硝酸还原酶γ亚基(功能性异化硝酸盐还原基因，nari)被抑制，表明甲烷产量和氮代谢低。此外,偏最小二乘路径模型显示,Shannon多样性指数与甲烷和氮代谢呈负相关(P<0.01),进一步证明，在大豆-萝卜轮作过程中，土壤细菌微生物组反应与GHG相关代谢密切相关。总的来说，我们的研究结果揭示了土壤微生物群落对与温室气体排放相关的功能代谢的响应，并为减少豆类和蔬菜轮作期间的温室气体排放提供了重要的见解。
