Plant growth promoting bacteria (PGPB) are an efficient and sustainable alternative to mitigate biotic and abiotic stresses in maize. This work aimed to sequence the genome of two Bacillus strains (B116 and B119) and to evaluate their plant growth-promoting (PGP) potential in vitro and their capacity to trigger specific responses in different maize genotypes. Analysis of the genomic sequences revealed the presence of genes related to PGP activities. Both strains were able to produce biofilm and exopolysaccharides, and solubilize phosphate. The strain B119 produced higher amounts of IAA-like molecules and phytase, whereas B116 was capable to produce more acid phosphatase. Maize seedlings inoculated with either strains were submitted to polyethylene glycol-induced osmotic stress and showed an increase of thicker roots, which resulted in a higher root dry weight. The inoculation also increased the total dry weight and modified the root morphology of 16 out of 21 maize genotypes, indicating that the bacteria triggered specific responses depending on plant genotype background. Maize root remodeling was related to growth promotion mechanisms found in genomic prediction and confirmed by in vitro analysis. Overall, the genomic and phenotypic characterization brought new insights to the mechanisms of PGP in tropical Bacillus.

中文翻译：

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基因组指导的热带芽孢杆菌菌株有效促进玉米生长的见解。

促进植物生长的细菌（PGPB）是缓解玉米中生物和非生物胁迫的有效且可持续的替代方法。这项工作旨在对两个芽孢杆菌菌株（B116和B119）的基因组进行测序，并评估其体外植物促生长（PGP）潜力。以及它们在不同玉米基因型中引发特异性反应的能力。对基因组序列的分析揭示了与PGP活性有关的基因的存在。两种菌株都能产生生物膜和胞外多糖，并能溶解磷酸盐。菌株B119产生了大量的IAA样分子和植酸酶，而菌株B116则能够产生更多的酸性磷酸酶。接种了两种菌株的玉米幼苗都受到了聚乙二醇诱导的渗透胁迫，并显示出较粗的根部增加，从而导致较高的根部干重。接种还增加了总干重并改变了21种玉米基因型中16种的根系形态，表明该细菌根据植物基因型背景触发了特异性反应。体外分析。总体而言，基因组和表型表征为热带芽孢杆菌中的PGP机制带来了新见解。