The soybean rhizosphere has a specific microbial community, but the differences in microbial community structure between different soybean genotypes have not been explained. The present study analyzed the structure of the rhizosphere microbial community in three soybean genotypes. Differences in rhizosphere microbial communities between different soybean genotypes were verified using diversity testing and community composition, and each genotype had a specific rhizosphere microbial community composition. Co-occurrence network analysis found that different genotype plant hosts had different rhizosphere microbial networks. The relationship between rhizobia and rhizosphere microorganisms in the network also exhibited significant differences between different genotype plant hosts. The ecological function prediction found that different genotypes of soybean recruited the specific rhizosphere microbial community. These results demonstrated that soybean genotype regulated rhizosphere microbial community structure differences. The study provides a reference and theoretical support for developing soybean microbial inoculum in the future.
Organic acids are one of the most important factors influencing fruit flavors. The predominant organic acid in most pear cultivars is malic acid, but the mechanism controlling its accumulation remains unclear. In this study, by comparing gene expression levels and organic acid content, we revealed that the expression of PbPH5, which encodes a P3A-ATPase, is highly correlated with malic acid accumulation in different pear species, with correlation coefficients of 0.932**, 0.656*, 0.900**, and 0.518* (*, P<0.05 or **, P<0.01) in Pyrus bretschneideri Rehd., P. communis Linn., P. pyrifolia Nakai., and P. ussuriensis Maxim., respectively. Moreover, the overexpression of PbPH5 in pear significantly increased the malic acid content. In contrast, silencing PbPH5 via RNA interference significantly decreased its transcript level and the pear fruit malic acid content. A subcellular localization analysis indicated that PbPH5 is located in the tonoplast. Additionally, a phylogenetic analysis proved that PbPH5 is a PH5 homolog gene that is clustered with Petunia hybrida, Malus domestica, and Citrus reticulata genes. Considered together, these findings suggest PbPH5 is a functionally conserved gene. Furthermore, the accumulation of malic acid in pear fruits is at least partly related to the changes in PbPH5 transcription levels.