Microbial community in the potato rhizosphere in the Bashang region

The composition and functional characteristics of the bacterial community in crop rhizosphere soil play a crucial role in soil health, nutrient cycling, and crop growth. However, there has been limited research on the bacterial communities in the potato rhizosphere of the Bashang region, a major potato-producing area in China. This study employed metagenomic sequencing to examine the bacterial community composition and functional traits of potato rhizosphere soils across three sites in Zhangbei and Guyuan Counties, Bashang region: Zhangbei Experimental Station of Zhangjiakou Academy of Agricultural Sciences (site 1); Zhangbei Experimental Station of Hebei Agricultural University (site 2); and Guyuan Experimental Station, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences (site 3). The results showed that Proteobacteria, Actinobacteria, and Acidobacteria were the dominant phyla in the potato rhizosphere soils in three sites of the two counties. However, there were significant differences in the alpha diversity of bacterial communities, with higher richness and diversity indices in Guyuan County than in Zhangbei County. LEfSe (Line Discriminant AnalysisEffect Size) analysis identified 16 bacterial groups that exhibited significant differences among 3 sites of the two counties, with Acidobacteria being an important differential group. The LDA (Linear Discriminant Analysis) score of Acidobacteria at site 3 was higher than that of other differential bacterial groups, indicating its greater impact on the intergroup differences. Overall, site 3 had the highest number of differential bacterial taxa in the rhizosphere soil, followed by site 2, while site 1 had the fewest differential bacterial groups. Correlation analysis of soil fertility indicators and microbial community structure at genus level revealed that soil organic matter was significantly positively correlated with Steroidobacter and available potassium was positively correlated with Bradyrhizobium and significantly negatively correlated with Luteitalea. These correlations suggested that certain bacterial groups played a role in nutrient cycling, especially in relation to soil fertility parameters, which may have influenced potato growth and yield in the region. The functional analysis of the potato rhizosphere soil bacterial communities highlighted that amino acid transport and metabolism, as well as energy production and conversion, were the primary functional traits of the bacterial communities in the Bashang region. The relative annotation abundance of these functions was highest at site 1 and lowest at site 3, indicating location-specific variations in microbial functional activity. Additionally, among the carbohydrate-active enzymes, glycosyltransferases exhibited the highest relative abundance, suggesting a significant role in carbohydrate metabolism in the rhizosphere. The relative abundance of carbohydrate-binding modules was the highest at site 3 and lowest at site 2, further reflecting the functional diversity across locations. The alpha diversity index was highest at site 3, indicating that the bacterial communities in the potato rhizosphere soil at site 3 were the most diverse. However, the soil at site 3 had the lowest levels of available potassium and available phosphorus contents among the three sites and the second highest organic matter content. This suggested that the levels of organic matter, available potassium, and available phosphorus in the potato rhizosphere soils of the Bashang region were not solely dependent on microbial diversity but may have been related to the abundance of certain key microorganisms.