Award details

An integrated approach to understanding desiccation tolerance with applications in the food industry

Reference	BB/C512688/1
Principal Investigator / Supervisor	Professor Simon McQueen-Mason
Co-Investigators / Co-Supervisors	Professor Peter Lillford
Institution	University of York
Department	Biology
Funding type	Research
Value (£)	292,201
Status	Completed
Type	Research Grant
Start date	03/06/2005
End date	02/06/2008
Duration	36 months

Abstract

The use of dried products and ingredients in the food industry is attractive because such products are light, easy to transport and store and have a long shelf life. There are limitations on the range of products that can be stored dry and rehydrated for consumption due to poor quality, in terms of texture as a result of inefficient rehydration. Solutions to technological problems can often be encountered in the natural world where organisms have evolved means to deal with similar environmental problems through the process of natural selection. A good example of this can be seen in the antifreeze proteins that have been evolved by a number of organisms to prevent damage caused by ice crystal growth in their body fluids at low temperatures, and which are now finding applications in the frozen foods industry. Craterostigma plantagineum is one of the few higher plants that can withstand dehydration throughout its vegetative tissues, and dried plants can successfully rehydrate and resume cellular activity within hours of receiving water. We propose that information relating to the ability of this plant to survive drying and rapidly rehydrate to its native form will be direct applications in the food industry and the current proposal is aimed at initiating this process. One of the main problems associated with drying fruit and vegetable materials results from the hardening of cell walls and their recalcitrance to rehydrating back to their native state. During drying, the tissues of C. plantagineum contract to about 15 per cent of their initial size and a key aspect of survival of drying in this plant resides in the ability of cell walls to fold around cells as they shrink, thus maintaining cellular integrity. This indicates a degree of flexibility in the cell walls of this species that is not encountered in other plants. We have shown that wall extensibility increases in C. plantagineum leaves during drying indicating active modification of walls during this process. Wehave also found that expansin activity rises in a similar manner and have cloned an expansin cDNA (CpEXPA1) that shows increased transcript abundance during drying, indicating a role in wall folding. We propose to study the function of this expansin gene in C. plantagineum, by silencing its transcriptional activity in transgenic plants using an RNAi post transcriptional silencing approach and examining the ability of the transgenic plants to fold their cell walls and survive drying. We will examine the expression patterns and transcriptional regulation of the CpEXPA1 gene by promoter-reporter studies. A major objective is to characterise other changes taking place in C. plantagineum cell walls during drying and rehydration. To this end we will analyse changes in the cell wall proteome during these processes using cell wall protein 2-dimensional electrophoresis, peptide mass fingerprinting and deriving peptide sequences with 2-dimensional MALDI mass spectrometry. CDNAs encoding several target proteins will be cloned and their transcript accumulation profiles characterised to identify proteins involved in modifying walls during dehydration and rehydration. We will examine the functional role of specific wall polysaccharides by digesting leaf discs with purified wall hydrolases and analysing the impact of this on drying. We will also monitor wall polysaccharides for changes in composition and linkage during the drying process. Initial studies indicate that expansins and other wall proteins from C. plantagineum can increase the rate of rehydration of dried vegetable tissues. We will examine the utility of these proteins to speed up rehydration and improve the recovery of texture in dried food products. As well as providing novel methods for food processing, this work is also likely to generate valuable information relevant to the ability of plants to survive drought.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search