Functional characterization of MhbZIP62 in regulating drought tolerance in apple

Area of Science:

• Plant Biology
• Molecular Genetics
• Agricultural Science

Background:

• Drought stress poses a significant threat to apple cultivation and industry sustainability.
• Understanding the genetic mechanisms underlying plant drought tolerance is crucial for developing resilient crops.

Purpose of the Study:

• To identify and characterize apple MhbZIP genes involved in drought stress response.
• To elucidate the functional roles of MhbZIP62 and MhbZIP23 in conferring drought tolerance.
• To investigate the synergistic interaction between MhbZIP62 and MhbZIP23.

Main Methods:

• Bioinformatic analysis of 19 apple MhbZIP genes.
• Transcriptional assays using PEG 6000, mannitol, and abscisic acid (ABA) treatments.
• Functional analysis via overexpression in transgenic tobacco and apple calli, and VIGS-mediated knockdown.
• Yeast two-hybrid and biochemical assays to confirm protein interactions.

Main Results:

• MhbZIP62 overexpression significantly enhanced drought tolerance, increased ABA levels, and boosted antioxidant enzyme activity.
• Knockdown of MhbZIP62 impaired drought tolerance, with partial rescue by exogenous ABA.
• MhbZIP62 and MhbZIP23 interact physically, and their co-overexpression synergistically improved drought resistance.
• MhbZIP23 silencing aggravated drought symptoms, indicating its crucial role in drought adaptability.

Conclusions:

• The MhbZIP62-MhbZIP23 module positively regulates drought tolerance in apple and tobacco calli.
• These genes are involved in ABA-dependent drought regulatory pathways.
• The findings provide a theoretical basis for molecular breeding and agronomic improvement of drought-resistant apple varieties.