By Blake Jackson
A study from the University of Kentucky’s Martin-Gatton College of Agriculture, Food and Environment sheds new light on how plants sometimes fail to properly relay internal disease alerts.
Although plants lack blood, nerves, or immune cells like animals, they still rely on complex chemical signaling to defend themselves. When a leaf becomes infected, it can trigger warning signals that travel through the plant, preparing other tissues for potential attack.
The study reveals that this communication system can be disrupted when levels of nitric oxide (NO) become too high. The research, published in Science Advances under the title “Excess nitric oxide alters cellular pH to restrict salicylic acid movement and systemic immunity,” explains how this imbalance interferes with plant immune signaling.
Nitric oxide is a naturally occurring molecule in both plants and animals. It supports growth, stress responses, and immune regulation in plants, but only when maintained at proper levels. The researchers found that excess NO can weaken plant defense responses.
Using Arabidopsis plants with a mutation in the GSNOR1 gene, the team observed reduced ability to activate systemic acquired resistance (SAR), a defense mechanism that spreads immune readiness throughout the plant after infection.
Salicylic acid, a key signaling compound related to aspirin, normally helps transmit these immune alerts. As Huazhen Liu, first author of the study, explained, “Systemic immunity is like plant memory,” said Huazhen Liu, first author of the work.
“After one leaf survives an attack, the plant needs to warn the rest of its body. Salicylic acid helps carry that alert signal.”
Researchers discovered that excessive nitric oxide disrupted cellular pH balance, creating acidic conditions outside cells and alkaline conditions inside them. This imbalance blocked the movement of salicylic acid, effectively trapping the signal.
“When nitric oxide levels become too high or uneven, they change the acidity around the cell,” Liu said. “That creates a barrier for salicylic acid. The signal gets trapped, and the rest of the plant does not get the warning.”
The study highlights how signal transport, not just signal production, is essential for plant immunity and may help improve future crop resilience strategies.
Photo Credit: kentucky-state-university
Categories: Kentucky, Crops, Education