Puccinia striiformis Effector PNPi Suppresses TaIAA14 Expression to Inhibit Host Cell Death Response

Area of Science:

• Plant Pathology
• Molecular Plant-Microbe Interactions
• Fungal Effector Biology

Background:

• Fungal pathogens secrete effectors to suppress host programmed cell death (hypersensitive response) for successful colonization.
• The precise mechanisms by which fungal effectors manipulate host cell death pathways are not fully understood.

Purpose of the Study:

• To investigate the role of the Puccinia striiformis effector PNPi in suppressing host cell death.
• To elucidate the molecular mechanisms underlying PNPi-mediated virulence and its interaction with host factors.

Main Methods:

• Functional analysis of the PNPi effector in Nicotiana benthamiana using BAX-induced cell death assays.
• RNA-sequencing to identify host genes affected by PNPi.
• Exogenous auxin application and gene silencing (NbIAA29) to assess auxin signaling involvement.
• In vivo interaction studies and virus-induced gene silencing (TaIAA14) in wheat.

Main Results:

• PNPi suppressed BAX-induced cell death in N. benthamiana, mediated by its FtsN domain.
• PNPi downregulated the auxin-responsive gene NbIAA29, and exogenous auxins partially restored cell death.
• PNPi interacted with wheat TaIAA14, and its knockdown enhanced fungal development and reduced wheat cell death.

Conclusions:

• The P. striiformis effector PNPi suppresses host cell death by targeting auxin signaling, specifically interacting with NbIAA29/TaIAA14.
• This effector-host interaction facilitates fungal infection and colonization.
• Findings provide insights into fungal virulence strategies and potential targets for disease control.