Comparative transcriptomic analysis provides novel insights into the difference in textural alteration between mealy...

Area of Science:

• Plant Science
• Biochemistry
• Molecular Biology

Background:

• Mealiness is a significant post-harvest textural defect in fruits, impacting consumer acceptance.
• Understanding the molecular mechanisms behind mealiness is crucial for developing strategies to maintain fruit quality.

Purpose of the Study:

• To investigate the underlying biochemical and transcriptomic differences between mealy and crisp apple varieties.
• To identify key genes and regulatory pathways involved in the development of apple mealiness.

Main Methods:

• Comparative analysis of biochemical characteristics and global transcriptomic profiling (RNA-sequencing) between mealy 'Hongjiangjun' (HJJ) and crisp 'Fuji' apples.
• Sensory evaluation and Scanning Electron Microscopy (SEM) for microstructure observation.
• Weighted gene co-expression network analysis (WGCNA) and quantitative real-time PCR (qRT-PCR) for gene validation.

Main Results:

• Mealy HJJ apples exhibited rapid textural deterioration and ethylene burst compared to crisp Fuji apples.
• Significant upregulation of genes encoding cell wall-modifying enzymes (e.g., polygalacturonase, β-galactosidase, expansin) and ethylene responsive factors (ERFs) was observed in mealy apples.
• Transcription factors MdbHLH63 and MdERF-like, along with MdGAL, were identified as core regulators strongly associated with mealiness.

Conclusions:

• Apple mealiness is associated with altered expression of cell wall-modifying enzymes and specific transcription factors.
• MdbHLH63 and MdERF-like play critical roles in regulating the mealiness process in apples.
• These findings offer insights into the genetic basis of textural differences between mealy and crisp apple cultivars.