ESCRT-I mediates FLS2 endosomal sorting and plant immunity

Area of Science:

• Plant immunity
• Molecular cell biology
• Endosomal trafficking

Background:

• The plant immune receptor FLAGELLIN SENSING 2 (FLS2) detects bacterial flagellin (flg22) at the plasma membrane.
• FLS2 internalization into endosomes is a key step following ligand perception.
• The precise molecular machinery governing FLS2 endosomal trafficking remains incompletely understood.

Purpose of the Study:

• To investigate the role of the Endosomal Sorting Complex Required for Transport (ESCRT)-I complex in FLS2 endocytosis and plant immunity.
• To elucidate the specific functions of ESCRT-I subunits, such as VPS37-1, in regulating FLS2 trafficking and downstream signaling.

Main Methods:

• Co-localization studies of FLS2 and VPS37-1 at endosomes.
• Immunoprecipitation assays to assess FLS2-VPS37-1 interactions upon flg22 treatment.
• Analysis of FLS2 endosomal localization and multivesicular body sorting in wild-type and vps37-1 mutant Arabidopsis.
• Assessment of plant immune responses, including stomatal closure, in response to bacterial infection.

Main Results:

• VPS37-1 co-localizes with FLS2 and interacts with it upon flg22 elicitation.
• Vps37-1 mutants exhibit defects in FLS2 endocytosis and impaired localization within multivesicular bodies.
• ESCRT-I loss-of-function compromises FLS2 endosomal sorting, affecting its late-stage trafficking.
• VPS37-1 and VPS28-2 are essential for flg22-induced stomatal closure and bacterial immunity.

Conclusions:

• ESCRT-I subunits, particularly VPS37-1, play a critical role in the late endosomal sorting of the plant immune receptor FLS2.
• The ESCRT-I complex is vital for flg22-activated stomatal defenses, highlighting its importance in plant immunity against bacterial pathogens.