Abstract

S2-08

A Family of Extensins Expressed during Post-Harvest Physiological Deterioration

Gómez-Vásquez R.¹, K. Reilly¹, J. Tohme² and J. R Beeching¹

1. Dept. of Biology & Biochemistry, University of Bath, Bath, BA2 7AY,

     UK       j.r.beeching@bath.ac.uk

Post-harvest physiological deterioration (PPD) can render cassava roots unpalatable and unmarketable within 48 hours of harvest.  Therefore, PPD is a major constraint to the development of cassava from a largely village-based crop to a commodity that can also supply urban populations, national industries and export markets.  Extending the shelf-life of cassava to one to two weeks would benefit farmers, processors and consumers alike and would impact positively on national economies of less-developed countries.  PPD is an active process involving changes in gene expression, protein synthesis and the accumulation of secondary metabolites.  It shares many features with wound responses in other plants, except that wound repair, which seals the wound sites and returns the plant to normal development, is inadequate in the detached root.  However, it is interesting to note that normal wound repair does occur if the cassava root remains attached to the plant.  Extensins are glycoproteins containing distinct repeat patterns that are insolubilised in the cell wall by H₂O₂, thereby strengthening the cell wall during normal development and wound repair.  By means of subtraction hybridisation and immuno techniques we have demonstrated the presence of a family of extensins that are expressed during PPD, thus confirming that important aspects of wound repair are still functional during the deterioration response.