MATE Transporter-Dependent Export of Hydroxycinnamic Acid Amides.

Area of Science:

• Plant Pathology
• Plant Biochemistry
• Molecular Plant-Microbe Interactions

Background:

• Arabidopsis thaliana employs multilayered defenses against Phytophthora infestans, the pathogen causing potato late blight.
• Surface-localized secondary metabolites play a crucial role in controlling pathogen entry.

Purpose of the Study:

• Investigate the role of surface-localized metabolites in controlling P. infestans entry into Arabidopsis.
• Identify specific compounds and genetic factors involved in plant defense at the leaf surface.

Main Methods:

• Untargeted metabolite profiling of P. infestans incubated on Arabidopsis leaves.
• In vitro assays to assess the activity of identified metabolites on P. infestans.
• Mutant analyses to determine genes involved in metabolite biosynthesis and transport.
• Genetic engineering of potato plants to express Arabidopsis defense-related genes.

Main Results:

• Coumaroylagmatine, a hydroxycinnamic acid amide, was identified as a key metabolite secreted into the P. infestans inoculum.
• Coumaroylagmatine demonstrated inhibitory activity against P. infestans spore germination in vitro.
• The p-coumaroyl-CoA:agmatine N4-p-coumaroyl transferase (ACT) and MATE transporter DTX18 were identified as crucial for coumaroylagmatine biosynthesis and secretion.
• Transgenic potato plants expressing ACT and DTX18 exhibited enhanced secretion of hydroxycinnamic acid amides, conferring resistance to P. infestans.

Conclusions:

• Secreted hydroxycinnamic acid amides, like coumaroylagmatine, contribute to plant defense by inhibiting pathogen spore germination at the leaf surface.
• The ACT and DTX18 genes from Arabidopsis can be utilized to engineer enhanced resistance in crops like potato.
• DTX18 functions as a specific transporter for hydroxycinnamic acid amides, facilitating their extracellular accumulation for defense.