Role of Chlorella fusca in promoting plant health through microbiota regulation in strawberry.

Aims: Chlorella is a microalgae species known to have plant growth-promoting (PGP) and disease-suppressing effects in crops. However, the mechanism of Chlorella's efficacy on crops remains unclear.

Methods and results: We investigated the hypothesis that Chlorella fusca CHK0059 promotes plant health by regulating the structure of the plant microbiota community. The phenotypes of the CHK0059-treated strawberry showed that the number of leaves and shoot weights was increased more than that of untreated plants. In microbiota communities, beta diversity showed no significant difference between CHK0059 treatment and nontreatment, while the CHK0059-treated root endosphere's alpha diversity decreased compared to untreated strawberries. Pseudomonas, Duganella, and Rhizomicrobium species appear to be correlated with CHK0059 treatment in the rhizosphere. These three bacteria possess the "P461-PWY" metabolic pathway, which can ferment hexitol to lactate, formate, ethanol, and acetate, lead to utilized phosphate solubility in soil, and potentially increased plant growth.

Conclusion: The promotion of strawberry growth by C. fusca correlates with changes in the plant microbiota, particularly the abundance of beneficial bacteria in the rhizosphere. These bacteria can enhance nutrient cycling, particularly phosphate solubility, contributing to improved plant health.