TaADF3, an Actin-Depolymerizing Factor, Negatively Modulates Wheat Resistance Against Puccinia striiformis.

Area of Science:

• Plant pathology
• Molecular biology
• Cytoskeleton dynamics

Background:

• The actin cytoskeleton is crucial for plant defense.
• Actin depolymerizing factors (ADFs) modulate the actin cytoskeleton.
• Limited knowledge exists on ADFs in plant-pathogen interactions.

Purpose of the Study:

• To isolate and characterize a wheat ADF gene (TaADF3).
• To investigate TaADF3's role in wheat defense against fungal pathogens.
• To explore TaADF3's involvement in stress responses and actin dynamics.

Main Methods:

• Gene isolation and characterization in wheat.
• Subcellular localization using particle bombardment in onion cells.
• Expression analysis under various stress and pathogen treatments.
• Virus-induced gene silencing to assess TaADF3 function.
• Analysis of reactive oxygen species (ROS) and hypersensitive response (HR).
• Microscopic observation of pathogen penetration and actin filament organization.

Main Results:

• TaADF3 is a stress-inducible gene found on wheat chromosomes 5A, 5B, and 5D.
• TaADF3 expression is induced by ABA, abiotic stresses, and virulent Puccinia striiformis f. sp. tritici (Pst), but repressed by avirulent Pst.
• Silencing TaADF3 enhanced resistance to avirulent Pst and reduced susceptibility to virulent Pst.
• TaADF3 knockdown hindered fungal penetration and haustoria formation, altering actin filament organization.
• These effects were linked to reactive oxygen species (ROS) production and hypersensitive response (HR).

Conclusions:

• TaADF3 positively regulates wheat tolerance to abiotic stresses.
• TaADF3 negatively regulates wheat resistance to Pst, acting in an ROS-dependent manner.
• TaADF3 influences fungal penetration by modulating actin cytoskeleton dynamics.