Plant defense and root microbiome

Plants face many challenges throughout their lives, including diseases caused by harmful pathogens such as bacteria, fungi, or viruses. These diseases can weaken the plant, slowing its growth and reducing its ability to produce food, flowers or seeds. In response, plants have evolved a range of adaptive strategies that enable them to resist or recover from these threats.

Systemic Acquired Resistance (SAR) is a natural defense system that plants use to protect themselves from diseases. When a plant gets infected by a harmful pathogen, it doesn’t just fight back at the spot of the attack. Instead, it sends a warning signal to the rest of the plant, so every part becomes better prepared to fight off future attacks. SAR is a smart defense system that helps plants remember” an attack and become stronger to prevent it from happening again.

Salicylic acid (SA) and N-hydroxy-pipecolic acid (NHP) are the two key metabolites that are involved in the SAR process. When the plant is attacked, the plant hormone SA helps trigger the immune response. It is like an “alarm bell”that tells the plant to start defending itself. NHP is another key molecule that helps activate and boost the SAR response. After the plant starts defending itself, NHP helps spread the signals throughout the entire plant, making the immune response stronger and more widespread. Together, these chemicals make the plant more resistant to diseases, helping it stay healthy without needing chemicals like pesticides.

The biosynthesis of NHP in plants involves several steps, starting from the amino acid L-lysine. First, L-lysine is converted into pipecolic acid (Pip), then adding a hydroxyl group to form N-hydroxy-pipecolic acid (NHP). Many studies have shown that this pipecolate metabolic pathway plays a crucial role in the activation of systemic acquired resistance in shoots, but its function in roots is unknown.

Under the soil, plant roots are not alone; they're surrounded by a variety of tiny microorganisms, including bacteria, fungi, and other microbes. These microbes play different roles. Some are helpful to the plant, working in partnership with the roots to improve nutrient absorption, protect against harmful diseases, and even help the plant deal with stress, like drought or soil pollution. Some can be harmful and may cause diseases that affect the plant's health, making it harder for the plant to grow. Together, these organisms form what is known as the plant root microbiome.

My project will use the model plant Arabidopsis to explore the interaction between plant pipecolate pathway and the root microbiome, which may uncover new ways to enhance plant defense, optimize growth, and promote sustainable farming practices.