High aluminum stress drives different rhizosphere soil enzyme activities and bacterial community structure between aluminum-tolerant and aluminum-sensitive soybean genotypes

Abstract

Aluminum is a major deleterious factor for soybean productivity in acidic soils. Soil enzyme activities and bacteria play important roles in improving the stress tolerance of soybean. We assessed soil enzyme activities and bacterial structure and functions in Al-tolerant (Al-T) and Al-sensitive (Al-S) soybean genotypes subjected to different Al stress. We used a pot experiment system and determined plant biomass, urease, acid phosphatase, catalase, sucrase, and amylase activities, soil chemical properties, and the rhizosphere bacterial community diversity and structure of Al-T and Al-S soybean genotypes under different Al concentrations (0, 0.2, and 0.4 Al3+ g kg−1). Significant differences in soil enzyme activities and bacterial community structure were only observed between Al-T and Al-S soybeans under high Al stress. We identified 23 operational taxonomic units (OTUs), including OTU46 (Tumebacillus), OTU253 (Granulicella), and OTU180 (Burkholderia), which may improve soybean tolerance to Al toxicity. The results of canonical correspondence analysis (CCA) indicated that NH4+-N was an important factor that drove bacterial community structure differences between the two genotypes. Al stress simplified the network structure in the Al-T soybean, which may cause the soil bacterial community to be easily influenced by biotic and abiotic factors. High Al stress drove different soil enzyme activities and bacterial community structures between Al-T and Al-S soybean genotypes, and NH4+-N was the most important factor that drove the bacterial community structure between the two genotypes. Al-T soybeans recruited Al-tolerant microorganisms, such as Tumebacillus, Granulicella, and Burkholderia, to improve the resistance to Al stress. Nevertheless, Al stress simplified the network structure in the Al-T soybeans, which may allow for the soil bacterial community to be easily influenced by other biotic and abiotic factors.