镉高/低积累玉米根际微生物移植对玉米生长与镉累积的影响

Rhizosphere microbiome transplantation affects the growth and cadmium accumulation of maize cultivars with high/low cadmium accumulation

摘要:

【背景】 根际微生物在作物镉耐性与累积中起着重要作用。【目的】 探究根际微生物相互移植对镉高/低积累玉米生长及镉累积的影响。【方法】 以铅锌矿区污染农田镉相对高积累(盘玉3号)和低积累(路单16号)的2个品种为研究材料，分析其根际细菌群落结构特征，进而开展移植根际微生物的盆栽试验，研究根际微生物移植后2个品种玉米的生长及镉累积特征。【结果】 2个品种玉米根际细菌群落组成相似，以变形菌门(Proteobacteria)、放线菌门(Actinomycetota)、酸杆菌门(Acidobacteriota)为主；优势属为链霉菌属(Streptomyces)、类诺卡氏菌属(Nocardioides)、栖大理石菌属(Marmoricola)等，但存在相对丰度的差异，盘玉3号根际类节杆菌属(Paenarthrobacter)的相对丰度显著高于路单16号。移植试验发现，镉低积累玉米根际微生物导致镉高积累玉米根系生物量、蒸腾速率和根系交叉数分别增加26.3%、31.3%和462%，植株镉生物转运系数降低58.5%；镉高积累玉米根际微生物导致低积累玉米株高、生物量分别降低15.0%、21.3%，地上部镉累积量显著降低61.6%。Mantel分析表明，路单16号根际微生物中变形菌门、放线菌门、酸杆菌门的相对丰度与盘玉3号的镉含量、镉累积量呈正相关，与株高、生物量呈负相关；盘玉3号根际微生物中放线菌门、酸杆菌门、芽单胞菌门(Gemmatimonadota)的相对丰度对路单16号株高、生物量、生物转运系数有正相关影响。【结论】 镉低积累玉米根际微生物能促进镉高积累玉米地下部镉的滞留，增强玉米对镉的耐性，根际微生物对玉米生长与镉累积起着特定的调控作用。

Abstract:

[Background] Rhizosphere microbiomes significantly influence plant cadmium (Cd) tolerance and accumulation. [Objective] To assess the effects of rhizosphere microbiome transplantation on the growth and Cd accumulation of maize cultivars with different Cd accumulation capacities. [Methods] Two maize cultivars, ‘Panyu 3’ with high Cd accumulation and ‘Ludan 16’ with low Cd accumulation, in the farmland exposed to lead-zinc mine contamination were selected. The structure of the rhizosphere bacterial community was analyzed. Subsequently, a pot experiment of rhizosphere microbiome transplantation was conducted to assess the growth and Cd accumulation in the two maize cultivars post transplantation. [Results] The rhizosphere bacterial communities of both maize cultivars exhibited similar composition, being dominated by Proteobacteria, Actinomycetota, and Acidobacteriota at the phylum level and Streptomyces, Nocardioides, and Marmoricola at the genus level. The dominant genera presented distinct variations in relative abundance between the two cultivars. Notably, Paenarthrobacter exhibited a significantly greater abundance in the rhizosphere of ‘Panyu 3’ than in the rhizosphere of ‘Ludan 16’. The transplantation experiment demonstrated that the rhizosphere microbiome from the maize cultivar with low Cd accumulation enhanced the root biomass, transpiration rate, and root intersection number by 26.3%, 31.3%, and 462%, respectively, and reduced the Cd translocation factor by 58.5% in the maize cultivar with high Cd accumulation. The rhizosphere microbiome from the maize cultivar with high Cd accumulation diminished the plant height, biomass, and aboveground Cd accumulation by 15.0%, 21.3%, and 61.6%, respectively, in the maize cultivar with low Cd accumulation. Mantel analysis revealed that the relative abundance of Proteobacteria, Actinomycetota, and Acidobacteriota in the rhizosphere of ‘Ludan 16’ had positive correlations with the Cd content and accumulation and negative correlations with the plant height and biomass of ‘Panyu 3’. The relative abundance of Actinomycetota, Acidobacteriota, and Gemmatimonadota in the rhizosphere of ‘Panyu 3’ was positively correlated with the plant height, biomass, and translocation factor of ‘Ludan 16’. [Conclusion] The rhizosphere microbiome from the maize cultivar with low Cd accumulation significantly facilitates Cd sequestration in the roots of the maize cultivar with high Cd accumulation, augmenting maize tolerance to Cd. Rhizosphere microbiomes exert specific regulatory effects on maize growth and Cd accumulation.