Aluminum induced flavonols in root exudates: Orchestrating rhizosphere bacteria to fuel tea plant growth

Plant-soil-microbe interactions can affect plant growth, development, and health. Plants can secrete bioactive molecules into the rhizosphere to alter the soil microbiota, further influencing plant growth. In this paper, the effects of flavonols secreted by tea roots on the remodeling of rhizosphere bacteria and on growth of tea plants were explored. Aluminum treatment significantly promoted the growth of tea plants, the accumulation of flavonols glycosides in the roots and the secretion of flavonols glycosides from roots. 16S rRNA analysis indicated that after aluminum treatment, the rhizosphere bacteria Burkholderia of the Proteobacteria phylum were significantly enriched. Compared to 'Longjin43' (LJ43), in roots of 'Huangjinye' (HJY), more flavonols were accumulated, so did in the root exudates. Moreover, Burkholderia in the rhizosphere of 'HJY' was significantly enriched. The results of correlation analysis indicated that the abundance of Burkholderia was significantly positively correlated with the secretion of flavonols under aluminum treatment or in different tea cultivar. Then 0.05 mM kaempferol were exogenous application to confirm the growth-promoting effect of flavonols on tea plants and the recruitment of Burkholderia in rhizosphere of tea roots. In conclusion, tea roots secrete flavonol glycosides into the rhizosphere soil, which can recruit Burkholderia and further promote the growth of tea plants. This study laid foundation for the subsequent development of bacterial fertilizers to promote the growth of tea plants.