Continuous recirculation of hydroponic-nutrient solutions shifts bacterial communities and induces plant-defense gene expression in lettuce

<i>Pythium myriotylum</i> is the causal agent of root rot and wilt disease, which can cause significant damage to lettuce in hydroponic systems. Root rot can be challenging to treat with traditional methods once it develops, often resulting in the destruction of the entire crop. Reused nutrient solutions have been reported to harbor microorganisms that may affect disease suppression. Examining how bacterial communities in recycled nutrient solutions change and trigger plant-defense genes may contribute to the reduction of Pythium root rot and provide chemical-free and cost-effective alternatives for soilless cultivation systems. Future studies focusing on specific microorganisms and their bioactive compounds will be essential for advancing biological control methods in hydroponic crop systems.