Mutations in CmVPS41 controlling resistance to cucumber mosaic virus display specific subcellular localization

Area of Science:

• Plant Pathology
• Molecular Biology
• Genetics

Background:

• Cucumber mosaic virus (CMV) resistance in melon (Cucumis melo L.) is controlled by the recessive gene cmv1.
• The cmv1 gene encodes vacuolar protein sorting 41 (CmVPS41), which restricts CMV to bundle sheath cells, preventing systemic infection.
• Specific mutations in CmVPS41 (G85E or L348R) confer resistance in different melon accessions.

Purpose of the Study:

• To investigate the subcellular localization of CmVPS41 in resistant and susceptible melon accessions.
• To determine the structural differences in CmVPS41 localization and their correlation with CMV resistance.
• To understand the role of CmVPS41 localization in the plant's defense against CMV.

Main Methods:

• Analysis of CmVPS41 subcellular localization in Nicotiana benthamiana using resistant and susceptible melon accessions.
• Creation of artificial CmVPS41 variants with specific resistance mutations in a susceptible genetic background.
• Coexpression of CmVPS41 with viral movement proteins and observation in CMV-infected plants.

Main Results:

• Resistant CmVPS41 localized to intravacuolar invaginations, while susceptible CmVPS41 showed nuclear and membrane spots and transvacuolar strands, both associated with late endosomes.
• Absence of transvacuolar strands in CmVPS41 variants correlated strongly with resistance.
• CMV infection induced CmVPS41 relocalization, with susceptible CmVPS41 showing fewer transvacuolar strands and resistant CmVPS41 showing some membrane spots.

Conclusions:

• Transvacuolar strands associated with susceptible CmVPS41 facilitate CMV infection.
• CmVPS41 localization within late endosomes is crucial for CMV resistance.
• CmVPS41 undergoes dynamic relocalization during CMV infection, suggesting an active role in plant defense.