Insight Into Function and Subcellular Localization of Plasmopara viticola Putative RxLR Effectors

Area of Science:

• Plant Pathology
• Molecular Biology
• Oomycete Biology

Background:

• Grapevine downy mildew, caused by Plasmopara viticola, is a major global threat to grape production.
• Understanding pathogen effectors is crucial for disease management, but their functions remain largely unknown.

Purpose of the Study:

• To analyze the potential functions of 26 Plasmopara viticola effectors from a highly virulent strain.
• To investigate effector-mediated modulation of plant cell death and subcellular localization.

Main Methods:

• Transient expression assays in Nicotiana benthamiana to assess cell death suppression/induction.
• Subcellular localization studies in N. benthamiana and Vitis vinifera cells.
• Sequence analysis and expression profiling of selected effectors.

Main Results:

• Most P. viticola effectors suppressed BAX/INF1-induced cell death; seven induced cell death.
• Effector localization in N. benthamiana mirrored that in Vitis vinifera, with 17/26 targeting the nucleus (nucleoplasm or nucleolus).
• Closely related effectors with similar localization exhibited distinct functions and expression patterns.

Conclusions:

• Plasmopara viticola effectors display significant functional diversity.
• Nuclear localization is common, but effector functions are not solely determined by sequence or localization.
• This study provides insights into the molecular mechanisms of grapevine downy mildew pathogenesis.