Mechanical Pruning Induces Distinct Metabolic Responses in Slender Spindle-Shaped Apple Orchards

Area of Science:

• Horticultural Science
• Plant Physiology
• Molecular Biology

Background:

• Mechanical pruning (MP) offers a labor-efficient alternative to hand pruning (HP) in apple orchards.
• Understanding the physiological and molecular impacts of MP on apple trees is crucial for sustainable production.

Purpose of the Study:

• To compare the physiological and transcriptional responses of apple trees to MP and HP.
• To investigate the effects of pruning methods on hormone metabolism, photosynthesis, and stress adaptation.

Main Methods:

• Apple trees were subjected to MP and HP in an orchard setting.
• Transcriptomic analysis was employed to assess gene expression changes at multiple time points post-pruning.

Main Results:

• MP led to the downregulation of light-harvesting complex genes (e.g., *MdLhcb*) and flavonoid biosynthesis genes (e.g., *MdDFR*).
• Stress-responsive genes (e.g., *MdNHL3*) were upregulated following MP, indicating activation of adaptive pathways.
• HP resulted in more moderate gene expression changes compared to MP.

Conclusions:

• Pruning methods distinctly influence apple tree recovery and gene expression dynamics.
• Findings offer insights for optimizing pruning systems to enhance apple production efficiency and quality under labor constraints.