2024年6月25日，The Plant Journal杂志在线发表了中国农业大学园艺学院韩振海/王忆教授团队题为“Bacillus B2 promotes root growth and enhances phosphorus absorption in apple rootstocks by affecting MhMYB15”的研究文章。 该研究揭示了不同磷效率的苹果砧木根际微生物群落具有显著差异，且根系转录因子MhMYB15响应芽孢杆菌B2促进根系发育和磷吸收的分子机制。
Phosphorus is an essential nutrient for plant growth, but phosphorus in soil is easily chelated with metal ions such as iron, aluminum, and calcium to form complexes, resulting in phosphate ions being highly fixed in mineral soils, making it difficult for plants to absorb and utilize effectively. The phosphorus-solubilizing bacteria in rhizosphere growth-promoting bacteria can activate the immobilized phosphorus element to promote the growth and development of woody plants, but the intrinsic molecular mechanism of how plants respond to phosphate-solubilizing bacteria is not well understood.
In this study, 16S rDNA and homologous genes encoding microbial alkaline phosphomonoesterase (phoD) were sequenced, and the rhizosphere microbiota of apple rootstocks with different phosphorus efficiencies were measured, and it was found that the phosphorus efficient rootstock (PE) was significantly enriched in functional rhizosphere microbial communities. Furthermore, the screening, isolation and identification of Bacillus B2 was returned to the rhizosphere of apple rootstock, and it was found that the soluble phosphorus content in the rhizosphere soil was significantly increased. At the same time, this process stimulates root development of the rootstock and enhances phosphorus uptake by the plant. Further studies showed that the transcription factor MhMYB15 could respond to Bacillus B2, and that MhMYB15 could directly bind to downstream functional genes (chalcone synthase MhCHS2 and phosphorus transporter MhPHT1; 15) of the promoter region. RNAi-MhMYB15 silent lines failed to induce the increase of flavonoid content and phosphorus in roots under Bacillus B2 treatment. In summary, this study elucidated that MhMYB15 actively responds to Bacillus B2 by regulating flavonoid accumulation and phosphorus uptake, thereby affecting plant growth and development. The research results provide a theoretical basis for the selection of nutrient efficient absorption materials and the utilization of bacterial fertilizer.
Pattern diagram of MhMYB15-mediated phosphorus uptake caused by differences in microbial communities in apple rootstocks with different phosphorus efficiencies
Paper Links:
https://onlinelibrary.wiley.com/doi/10.1111/tpj.16893?af=R
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