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Changes in cell wall composition during ripening of grape berries
1Department of Plant Science, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia (K.J.N., G.B.F.).
Plant Physiology
|November 10, 1998
Summary
Grape berry cell walls did not change thickness during ripening. Key changes in pectin (galacturonan) and protein (hydroxyproline) content occurred, influencing fruit softening.
Area of Science:
- Plant Biology
- Fruit Development
- Biochemistry
Background:
- Grape berry ripening involves significant textural changes, particularly softening.
- Cell wall modifications are critical for fruit texture development.
- Understanding grape cell wall composition changes is key to explaining ripening.
Purpose of the Study:
- To investigate changes in grape berry cell wall composition during ripening.
- To correlate cell wall structural changes with fruit softening.
- To analyze protein and polysaccharide dynamics in developing grape cell walls.
Main Methods:
- Isolation of cell walls from grape mesocarp at various developmental stages.
- Microscopy (fluorescence and light) to assess cell wall thickness.
- Analysis of protein content, amino acid composition, and polysaccharide composition and solubility.
Main Results:
- Cell wall thickness remained constant during mesocarp cell expansion.
- Protein content increased significantly post-veraison, with a 3-fold rise in hydroxyproline.
- Pectic polysaccharides showed decreased arabinogalactan and increased, more soluble galacturonan.
- Cellulose and xyloglucan content remained relatively stable.
Conclusions:
- Grape berry softening involves significant modifications in specific cell wall polysaccharides and proteins, not just overall thickness.
- Changes in pectin composition and protein content are major drivers of fruit texture changes during ripening.
- These findings provide insight into the biochemical basis of grape texture development.