Plant Defense Elicitation by the Hydrophobin Cerato-Ulmin and Correlation with Its Structural Features

Area of Science:

• Plant pathology
• Mycology
• Protein biochemistry

Background:

• Cerato-ulmin (CU) is a hydrophobin protein from fungi that self-assembles at interfaces, altering surface wettability.
• This property may aid fungal colonization and infection of host plants like elm trees.

Purpose of the Study:

• To investigate the defense-eliciting capacity of Cerato-ulmin (CU) in non-host plants.
• To determine the role of CU's conformation and physical properties in its interaction with plant defense mechanisms.

Main Methods:

• Experiments were conducted using *Arabidopsis* as a non-host plant model.
• Assays included monitoring phytoalexin synthesis and reactive oxygen species (ROS) production.
• Computational analysis identified dynamic hydrophobic clusters on CU.

Main Results:

• Cerato-ulmin (CU) successfully elicited defense reactions, including phytoalexin synthesis and ROS production, in *Arabidopsis*.
• The eliciting capacity of CU was more efficient in its soluble monomeric form.
• Two hydrophobic clusters on CU loops exhibit conformational plasticity, interconverting between disordered and β-strand-rich states.

Conclusions:

• Cerato-ulmin (CU) can induce defense responses in non-host plants.
• Protein plasticity, particularly the conformational flexibility of hydrophobic loops, is proposed as a key factor in CU's defense-eliciting capability.
• Understanding CU's interaction mechanism can inform strategies against fungal plant pathogens.