Ma Yuanyuan, Shen Yan, Zhou Xiaoping, Ma Hongbin, Lan Jian, Fu Bingzhe, Xue Quanhong
College of Forestry and Prataculture, Ningxia University, Yinchuan 750021, China.
Ningxia Rural Science and Technology Development Center, Yinchuan 750001, China.
Plants (Basel). 2024 Sep 16;13(18):2589. doi: 10.3390/plants13182589.
The growth and biological decline of alfalfa may be linked to the rhizosphere microbiome. However, plant-microbe interactions in the rhizosphere of alfalfa and associated microbial community variations with stand age remain elusive. This study explored the successional pattern of rhizosphere microbial communities across different aged alfalfa stands and its relationship with alfalfa decline. Rhizosphere soils were collected from 2- and 6-year-old alfalfa stands. Control soils were collected from interspaces between alfalfa plants in the same stands. Soil bacterial and fungal communities were characterized by 16S and ITS rRNA gene sequencing, respectively. Specific microbial taxa colonized the rhizosphere soils, but not the control soils. The rhizosphere-specific taxa mainly included potentially beneficial genera (e.g., , ) in the young stand and harmful genera (e.g., , ) in the old stand. Alfalfa roots regulated soil microbial communities by selective promotion or inhibition of distinct taxa. The majority of time-enriched taxa were reported as harmful fungi, whose relative abundances were negatively correlated with plant traits. Time-depleted taxa were mostly known as beneficial bacteria, which had relative abundances positively correlated with plant traits. The relative abundances of functional bacterial genes associated with vancomycin biosynthesis, zeatin biosynthesis, and amino acid metabolism trended lower in rhizosphere soils from the old stand. An upward trend was observed for fungal pathogens and wood saprotrophs with increasing stand age. The results suggest that root activity drives the negative succession of rhizosphere microbial communities during alfalfa decline in old stands.
苜蓿的生长和生物学衰退可能与根际微生物群有关。然而，苜蓿根际的植物-微生物相互作用以及相关微生物群落随林分年龄的变化仍不明确。本研究探讨了不同年龄苜蓿林分根际微生物群落的演替模式及其与苜蓿衰退的关系。从2年生和6年生苜蓿林分采集根际土壤。对照土壤取自同一林分中苜蓿植株之间的间隙。分别通过16S和ITS rRNA基因测序对土壤细菌和真菌群落进行表征。特定的微生物类群定殖于根际土壤，而非对照土壤。根际特异性类群主要包括幼龄林分中的潜在有益属（如 ， ）和老龄林分中的有害属（如 ， ）。苜蓿根通过选择性促进或抑制不同类群来调节土壤微生物群落。大多数随时间富集的类群被报道为有害真菌，其相对丰度与植物性状呈负相关。随时间减少的类群大多是已知的有益细菌，其相对丰度与植物性状呈正相关。与万古霉素生物合成、玉米素生物合成和氨基酸代谢相关的功能性细菌基因的相对丰度在老龄林分的根际土壤中呈下降趋势。随着林分年龄的增加，真菌病原体和木材腐生菌呈上升趋势。结果表明，在老龄林分苜蓿衰退过程中，根系活动驱动了根际微生物群落的负向演替。
