Bacillus amyloliquefaciens is a widely used plant growth-promoting rhizobacterium. To investigate its role and mechanisms in selenium (Se) biofortification in crops, a pot experiment with four treatments including no application of Se fertilizer and B. amyloliquefaciens (control), B. amyloliquefaciens application (BA), Se fertilizer application (Se), and combined B. amyloliquefaciens and Se fertilizer application (BA + Se) was conducted. The results showed that, BA + Se treatment significantly increased total biomass of tea seedling compared with control, BA and Se treatments. Additionally, compared with Se treatment, BA + Se treatment significantly increased the Se concentrations in root and leaf, and Se content in the whole tea seedling by 101.4%, 34.5%, and 149.5%, respectively; BA + Se treatment also significantly increased the soil exchangeable Se and total available Se concentrations. Compared with control, BA treatment upregulated the expression level of CsPHT1;2b; Se treatment upregulated the expression levels of CsSULTR1;1, CsSULTR1;2, CsPHT1;2a and CsPHT1;2b; BA + Se treatment upregulated the CsSULTR1;1 and CsPHT1;2a expression levels in tea seedling roots. The 16S rRNA indicated that BA and Se treatments had no effects on the diversity of rhizosphere bacterial community, but altered bacterial community composition. Soil pH was the most important environmental factor affecting rhizosphere bacterial community composition. BA + Se treatment significantly increased soil pH and the complexity of rhizosphere bacterial symbiotic network, compared with other three treatments. Furthermore, comparative analysis about rhizosphere soil properties and bacterial community composition and function between Se and BA + Se treatments, suggested that BA + Se treatment promoted soil Se availability by recruiting g_Sinomonas species and regulating the abundance of Se reductase in the rhizosphere.

解淀粉芽孢杆菌是一种广泛使用的植物促生长根杆菌。为研究其在作物硒 （Se） 生物强化中的作用和机制，进行了四种处理的盆栽试验，包括不施用硒肥和解淀粉芽孢杆菌（对照）、解淀粉芽孢杆菌施用 （BA）、硒肥施用 （Se） 以及解淀粉芽孢杆菌和硒肥联合施用 （BA + Se）。结果表明，与对照、BA 和 Se 处理相比，BA + Se 处理显著提高了茶树苗的总生物量。此外，与硒处理相比，BA + Se 处理显著提高了茶叶根中硒含量和全苗硒含量，分别提高了 101.4%、34.5% 和 149.5%;BA + Se 处理还显著提高了土壤可交换硒和总速效硒浓度。与对照相比，BA 处理上调了 CsPHT1 的表达水平;2b;Se 处理上调 CsSULTR1 的表达水平;1， CsSULTR1;2， CsPHT1;2a 和 CsPHT1;2b;BA + Se 处理上调 CsSULTR1;1 和 CsPHT1;茶苗根系中的 2a 表达水平。16S rRNA 表明 BA 和 Se 处理对根际细菌群落的多样性没有影响，但改变了细菌群落组成。土壤 pH 值是影响根际细菌群落组成的最重要环境因子。BA + Se 处理显著提高了土壤 pH 值和根际细菌共生网络的复杂性，与其他 3 种处理相比。 此外，对 Se 和 BA + Se 处理之间的根际土壤性质和细菌群落组成和功能的比较分析表明，BA + Se 处理通过募集g_Sinomonas物种和调节根际 Se 还原酶的丰度来促进土壤 Se 的可用性。