The RING-Type E3 Ligase XBAT35.2 Is Involved in Cell Death Induction and Pathogen Response

Area of Science:

• Plant molecular biology
• Plant immunity
• E3 ubiquitin ligase function

Background:

• XBAT35 is an Arabidopsis RING-type E3 ligase with isoforms XBAT35.1 and XBAT35.2.
• XBAT35.2 shares domain similarity with rice XA21 Binding Protein3, a known defense protein.

Purpose of the Study:

• To investigate the function of XBAT35.2 in plant defense and cell death.
• To elucidate the regulatory mechanisms of XBAT35.2 during pathogen attack.

Main Methods:

• Overexpression of XBAT35.2 in Nicotiana benthamiana to assess cell death induction.
• Gene knockout and overexpression of XBAT35 in Arabidopsis to study pathogen resistance.
• Protein localization studies using Golgi markers.
• Interaction assays with Accelerated Cell Death11 (ACD11).
• Ubiquitination and degradation assays.

Main Results:

• XBAT35.2 localizes to the Golgi and induces cell death requiring its RING domain.
• Loss of XBAT35 function compromises plant defense, while XBAT35.2 overexpression enhances resistance.
• XBAT35.2 is unstable and self-regulates degradation, but pathogen infection stabilizes it.
• XBAT35.2 interacts with ACD11 and promotes its proteasome-dependent degradation.
• Pathogen infection reduces ubiquitinated XBAT35.2 and ACD11, increasing XBAT35.2 and decreasing ACD11 abundance.

Conclusions:

• XBAT35.2 plays a critical role in plant cell death induction and defense against pathogens.
• Pathogen infection disrupts XBAT35.2 self-regulation, stabilizing the E3 ligase to bolster plant immunity.
• XBAT35.2 functions in pathogen defense by targeting ACD11 for proteasomal degradation.