Multi-omics analysis reveals the effects of three application modes of plant growth promoting microbes biofertilizer on potato (Solanum tuberosum L.) growth under alkaline loess conditions

Potato is an important crop due to its high contents of starch, protein, and various vitamins and minerals. Biofertilizers are composed of plant growth promoting microbes (PGPMs) which are essential for improving the growth and resistance of potato. However, little information has focused on the modes of inoculation of biofertilizers on plant growth and microecology. This study aims to reveal the response mechanism of the potato to three modes of inoculation of biofertilizers all containing PGPM Bacillus amyloliquefaciens EZ99, i.e. scattered mode of 5 kg/ha biofertilizer (M5), soaking seed tubers with dissolved 5 kg/ha biofertilizer (MZG), and scattered mode of 3 kg/ha biofertilizer + 2 kg/ha sucrose (MY34) in alkaline loess field through multi-omics analysis of transcriptome, metabolome and microbiome. The physiological result revealed that two application modes of equal amount of biofertilizer M5 and MZG significantly improved the growth and yield of potatoes. Furthermore, the transcriptome of potato exhibited sets of differentially expressed genes enriched in photosynthesis, sugar metabolism, and phenylpropanoid biosynthesis among the three modes, with the M5 mode exhibiting overall up-regulation of 828 genes. Based on the untargeted metabolomic analysis of potato tuber, M5 mode significantly accumulated sucrose, while MZG and MY34 mode significantly accumulated the stress metabolites euchrenone b6 and mannobiose, respectively. Besides, the microbial structure of potato rhizosphere showed that the diversity of bacteria and fungi was similar in all soils, but their abundances varied significantly. Specifically, beneficial Penicillium was enriched in M5 and MZG soils, whereas MY34 soil accumulated potential pathogens Plectosphaerella and saccharophilic Mortierella. Collectively, these e findings highlight that MZG is the most effective mode to promote potato growth and stimulate rhizosphere effect. The present study not only encourages sustainable agriculture through agroecological practices, but also provides broad prospects for the application of PGPM biofertilizer in staple foods.