Background and aims

Rhizosphere serves as a hotspot for phosphatase exudation, which is instrumental in organic P mineralization and thereby facilitates enhanced P uptake by plants. However, further exploration is required to elucidate mechanisms of P transformation regulated by microorganisms in rhizosphere hotspots.

Methods

Soil zymography was used to visualize rhizosphere hotspots associated with acid and alkaline phosphatase activities following P addition in two maize genotypes, Zhengdan958 (ZD958) and Xianyu335 (XY335). Metagenomic sequencing was used to investigate shifts in abundance and composition of P cycle genes and microbial communities within phosphatase hotspots.

Results

ZD958 exhibited higher shoot biomass than XY335 under same P conditions. Hotspots of phosphatase activity were predominantly located in the maize rhizosphere and decreased following P addition. Specifically, P addition resulted in an increase in the abundance of P-uptake and transport genes pstSCAB and a decrease in the abundance of P-starvation regulation gene phoB and inorganic P solubilization gene gcd in ZD958. The relative abundance of phytase-encoding gene (phy) significantly increased with P addition and correlated with soil available P (AP) in XY335. Among the microbial taxa containing hub genes, Streptomyces emerged as the most crucial predictor of soil AP and exhibited a significantly positive relationship with AP for both maize genotypes.

Conclusion

Our results visualized the rhizosphere phosphatase hotspots, revealing that the genes regulating P cycling differed while Streptomyces harboring P cycling hub genes improve P availability in both maize genotypes. These findings provide a scientific basis for increasing the P efficiency employing microbiology.

Graphical Abstract

中文翻译：

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根际磷酸酶热点： 受玉米品种和磷添加影响的微生物介导的 P 转化机制

 背景和目标

根际是磷酸酶渗出的热点，磷酸酶渗出有助于有机磷矿化，从而促进植物对磷的吸收增强。然而，需要进一步探索来阐明根际热点地区微生物调控的 P 转化机制。

 方法

土壤酶谱用于可视化两种玉米基因型 Zhengdan958 （ZD958） 和 Xianyu335 （XY335） 添加 P 后与酸和碱性磷酸酶活性相关的根际热点。宏基因组测序用于研究磷酸酶热点内 P 循环基因和微生物群落的丰度和组成的变化。

 结果

在相同 P 条件下，ZD958 的地上部生物量高于 XY335。磷酸酶活性的热点主要位于玉米根际，并在添加 P 后降低。具体来说，在 ZD958 中，P 添加导致 P 摄取和转运基因 pstSCAB 的丰度增加，以及 P 饥饿调节基因 phoB 和无机 P 溶解基因 gcd 的丰度降低。植酸酶编码基因 （phy） 的相对丰度随 P 的添加而显著增加，并与 XY335 中土壤速效 P （AP） 相关。在包含枢纽基因的微生物分类群中，链霉菌成为土壤 AP 的最关键预测因子，并且在两种玉米基因型中与 AP 均表现出显著的正相关关系。

 结论

我们的结果可视化了根际磷酸酶热点，揭示了调节 P 循环的基因不同，而携带 P 循环枢纽基因的链霉菌提高了两种玉米基因型的 P 可用性。se 研究结果为利用微生物学提高 P 效率提供了科学依据。

 图形摘要