PbrIDD2-PbrAPX14 Module Functions in the Ethylene-Mediated Ripening and Senescence Process of Pear Fruit.

Area of Science:

• Plant Physiology
• Molecular Biology
• Biochemistry

Background:

• Endogenous hydrogen peroxide (H₂O₂) acts as a secondary messenger in ethylene-dependent fruit ripening and senescence.
• The precise molecular mechanisms underlying H₂O₂'s role in fruit development remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms of ethylene-mediated H₂O₂ accumulation during pear fruit ripening and senescence.
• To investigate the role of PbrAPX14 in regulating H₂O₂ levels and its impact on ethylene production and fruit development.

Main Methods:

• Conjoint analysis of metabolite, enzyme activities, and gene expression profiles in the AsA-GSH cycle of 'Kolar' pear.
• Analysis of transcription factor (TF) expression profiles and experimental validation of TF binding to the PbrAPX14 promoter.
• In vitro and in vivo studies to assess PbrAPX14 function, H₂O₂ scavenging, and the effect of S-sulfenylation.

Main Results:

• PbrAPX14, a cytosolic enzyme, reduces H₂O₂, inhibits ethylene production, and delays fruit ripening and senescence.
• Nuclear PbrIDD2 directly binds to the PbrAPX14 promoter, activating its expression and enhancing H₂O₂ scavenging.
• Ethylene upregulates the S-sulfenylation of PbrAPX14, mitigating its function and facilitating H₂O₂ accumulation.

Conclusions:

• Both transcriptional (PbrIDD2) and post-translational (S-sulfenylation) regulation of PbrAPX14, influenced by ethylene, control pear ripening and senescence.
• The study reveals a novel regulatory pathway involving PbrAPX14 in managing endogenous H₂O₂ levels during fruit development.