Changes in root exudates and rhizospheric microbial functional capacities involved in carbon (C) decomposition and nitrogen (N) transformation of aluminum (Al)-tolerant and Al-sensitive soybean genotypes were investigated under Al stress. Rhizosphere soils were collected from rhizobox systems with two soybean genotypes. A wide range of microbial functional capacities were determined by functional gene arrays. Microbial functional capacities of rhizospheres were distinct between Al-tolerant and Al-sensitive genotypes, which were related to exchangeable Al concentrations. Functional capacities associated with decomposition of chemically recalcitrant C were lower in Al-tolerant than Al-sensitive genotypes, which was negatively correlated with the secretion rate of succinic acid. Microbial functional capacities were higher for nitrification but lower for denitrification in the rhizosphere of Al-tolerant than Al-sensitive genotype, which coincided with higher succinic acid secretion and lower abundance of microbial oxygen stress genes. Soybean biomass increased logarithmically with nitrification capacities. We concluded that exchangeable Al concentrations, root exudation, and microbial C and N cycling capacities were intrinsically linked, which served as a key mechanism for legume genotypes toward enhancing tolerance to Al stress occurring in acid soils.

中文翻译：

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根际微生物功能能力的变化有助于酸性土壤中基因型特异性大豆的铝耐受性

研究了在铝胁迫下根系分泌物和根际微生物功能能力的变化，这些微生物与铝 (Al) 耐受和铝敏感大豆基因型的碳 (C) 分解和氮 (N) 转化有关。根际土壤是从具有两种大豆基因型的根箱系统中收集的。广泛的微生物功能能力由功能基因阵列确定。根际微生物功能能力在耐铝基因型和铝敏感基因型之间是不同的，这与可交换的铝浓度有关。在耐铝基因型中，与化学顽固 C 分解相关的功能能力低于铝敏感基因型，这与琥珀酸的分泌速率呈负相关。与铝敏感基因型相比，耐铝根际微生物的硝化功能能力较高，但反硝化作用较低，这与较高的琥珀酸分泌和较低的微生物氧胁迫基因丰度相吻合。大豆生物量随硝化能力呈对数增加。我们得出结论，可交换的铝浓度、根系分泌物和微生物 C 和 N 循环能力具有内在联系，这是豆科植物基因型增强对酸性土壤中铝胁迫耐受性的关键机制。