Plants have the super ability to regulate their immune system's response when there is a higher risk of fungal infection, a new study has found.

Biologists from University of Warwick in collaboration with researchers from the University of Cape Town found that the internal molecular clock or circadian clock of plants is linked to their ability to resist infection early in the morning.

Plants utilize the circadian clock, an internal time-keeping mechanism that gives them ability to anticipate regular changes in the environment such as the presence of pathogens. This increases the level of plants' resistance to infection at dawn, the time fungal infection are seen most likely to occur. The resistance will pursue regardless when plants are placed under constant light during the day. 

The biologists also discovered that the internal molecular clock and immune response of plants are connected by a protein called JAZ6.

The researchers  infected plants with the pathogen Botrytis cinerea spores over a 24-hour-period and measured the lesions that appeared. They found that the plants injected with the pathogen in the morning were more resistant to infection and developed tiny lesions than the plants injected at night.

"Plants are able to predict when pathogen infection is more likely to occur and regulate their immune response to combat this, with plants being more resistant to infection after inoculation at dawn compared to inoculation at night," explained lead author Dr. Katherine Denby, from the University of Warwick's School of Life Science.

"This pattern showed us that resistance must be driven by the plant's internal clock," Claire Stoker, a doctorate student at the University of Warwick added.

In another study, it was found that the circadian clock also wards off insects as plants are able to predict or anticipate a raid by hungry herbivores. The study used a 12-hour light cycles to train the molecular clock. They found that plants that have clocks that are out of sync were eaten by insects while those with intact clocks were resistant to attacks.

The study was published in the journal The Plant Journal.

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