Jiangsu Academy of Forestry, Nanjing, China.
Jiangsu Suqian Environmental Monitoring Center, Suqian, China.
BMC Plant Biol. 2024 May 14;24(1):398. doi: 10.1186/s12870-024-05118-0.
The pollution of soil by heavy metals, particularly Cd, is constitutes a critical international environmental concern. Willow species are renowned for their efficacy in the phytoremediation of heavy metals owing to their high Cd absorption rate and rapid growth. However, the mechanisms underlying microbial regulation for high- and low-accumulating willow species remain poorly understood. Therefore, we investigated the responses of soil and rhizosphere microbial communities to high- and low-Cd-accumulating willows and Cd contamination. We analyzed soil properties were analyzed in bulk soil (SM) and rhizosphere soil (RM) planted with high-accumulating (H) and low-accumulating (L) willow species.
Rhizosphere soil for different willow species had more NH than that of bulk soil, and RM-H soil had more than RM-L had. The available phosphorus content was greater in hyper-accumulated species than it was in lower-accumulated species, especially in RM-H. Genome sequencing of bacterial and fungal communities showed that RM-L exhibited the highest bacterial diversity, whereas RM-H displayed the greatest richness than the other groups. SM-L exhibited the highest diversity and richness of fungal communities. Ralstonia emerged as the predominant bacterium in RM-H, whereas Basidiomycota and Cercozoa were the most enriched fungi in SM-H. Annotation of the N and C metabolism pathways revealed differential patterns: expression levels of NRT2, NarB, nirA, nirD, nrfA, and nosZ were highest in RM-H, demonstrating the effects of NOand N on the high accumulation of Cd in RM-H. The annotated genes associated with C metabolism indicated a preference for the tricarboxylic pathway in RM-H, whereas the hydroxypropionate-hydroxybutyrate cycle was implicated in C sequestration in SM-L.
These contribute to elucidation of the mechanism underlying high Cd accumulation in willows, particularly in respect of the roles of microbes and N and C utilization. This will provide valuable insights for repairing polluted soil using N and employing organic acids to improve heavy metal remediation efficiency.
土壤重金属污染，尤其是 Cd，是国际上关注的一个关键环境问题。柳树因其对重金属的高吸收速率和快速生长而被广泛认为是重金属植物修复的有效树种。然而，高、低积累柳树物种的微生物调控机制仍知之甚少。因此，我们研究了高、低 Cd 积累柳树和 Cd 污染对土壤和根际微生物群落的响应。我们分析了高、低积累柳树物种种植的原状土（SM）和根际土（RM）的土壤性质。
不同柳树的根际土壤比原状土壤有更多的 NH，而 RM-H 土壤比 RM-L 土壤有更多的 NH。超积累物种的有效磷含量大于低积累物种，尤其是在 RM-H 中。细菌和真菌群落的基因组测序表明，RM-L 表现出最高的细菌多样性，而 RM-H 比其他组具有更高的丰富度。SM-L 表现出最高的真菌群落多样性和丰富度。Ralstonia 在 RM-H 中成为优势细菌，而 Basidiomycota 和 Cercozoa 是 SM-H 中最丰富的真菌。N 和 C 代谢途径的注释显示出不同的模式：RM-H 中 NRT2、NarB、nirA、nirD、nrfA 和 nosZ 的表达水平最高，表明 NO 和 N 对 RM-H 中 Cd 的高积累有影响。与 C 代谢相关的注释基因表明，RM-H 中偏爱三羧酸途径，而 SM-L 中则涉及 C 固定的羟基丙酸-羟基丁酸循环。
这些研究有助于阐明柳树中 Cd 高积累的机制，特别是微生物和 N 和 C 利用的作用。这将为利用 N 修复污染土壤和利用有机酸提高重金属修复效率提供有价值的见解。
