Genetic determinants of textural modifications in fruits and role of cell wall polysaccharides and defense proteins in the protection against pathogens.

DARIO CANTU, ARIEL R VICENTE, L. CARL GREVE, JOHN M. LABAVITCH, ANN L. T. POWELL.

Fresh Produce

Global Science Books

Año: 2007 vol. 1 p. 101 - 110

Plant cell wall metabolism has been suggested to play a major role in the textural changes associated with fruit ripening. The significance of cell wall degrading agents such as polygalacturonase (PG), pectin methylesterase (PME), â-galactosidase (â-gal), endo-1,4-â-glucanase (EGase) and pectate lyase (PL) has led to important advances in our understanding of cell wall disassembly but studies looking at the way these agents may interact and work in concert as ‘a cell wall disassembly line’ will increase our understanding of fruit softening. In addition, the in vivo contribution of other cell wall degrading agents such as á-arabinofuranosidase (á-ara), rhamnogalacturonase (RGase), acetylesterase (AE) and xyloglucan transglycosylase hydrolase (XTH) to fruit softening remains to be evaluated. The role of the cell walls in the resistance against pathogens is another area of great interest from a postharvest perspective. Cell wall modifications that could reduce fruit susceptibility to decay would be of great value because of the potential to reduce pathological problems occurring during storage, handling and distribution. Interestingly it has been recently shown in Arabidopsis that the over-expression of a plant pectin methylesterase inhibitor can restrict fungal infection. It would be interesting to test whether or not this approach might be useful to control fruit postharvest diseases. Another aspect to explore further includes the determination of the potential applications of proteins influencing the ability of pathogen glycosidases to cleave plant cell wall polysaccharides such as polygalaturonases, pectin or pectate lyases and xyloglucanase inhibiting proteins. The present work describes some of the genetic determinants of the textural modifications in horticultural commodities and discusses the role of plant cell wall polysaccharides and defense proteins as barriers against postharvest pathogens.â-galactosidase (â-gal), endo-1,4-â-glucanase (EGase) and pectate lyase (PL) has led to important advances in our understanding of cell wall disassembly but studies looking at the way these agents may interact and work in concert as ‘a cell wall disassembly line’ will increase our understanding of fruit softening. In addition, the in vivo contribution of other cell wall degrading agents such as á-arabinofuranosidase (á-ara), rhamnogalacturonase (RGase), acetylesterase (AE) and xyloglucan transglycosylase hydrolase (XTH) to fruit softening remains to be evaluated. The role of the cell walls in the resistance against pathogens is another area of great interest from a postharvest perspective. Cell wall modifications that could reduce fruit susceptibility to decay would be of great value because of the potential to reduce pathological problems occurring during storage, handling and distribution. Interestingly it has been recently shown in Arabidopsis that the over-expression of a plant pectin methylesterase inhibitor can restrict fungal infection. It would be interesting to test whether or not this approach might be useful to control fruit postharvest diseases. Another aspect to explore further includes the determination of the potential applications of proteins influencing the ability of pathogen glycosidases to cleave plant cell wall polysaccharides such as polygalaturonases, pectin or pectate lyases and xyloglucanase inhibiting proteins. The present work describes some of the genetic determinants of the textural modifications in horticultural commodities and discusses the role of plant cell wall polysaccharides and defense proteins as barriers against postharvest pathogens.