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A novel strategy for reducing wastage in potato storage by improved control of tuber dormancy. - LK09105

Objective


The proof of concept project is based on the prediction that potato tubers, in which the CK (cytokinin) ribotide to CK riboside conversion in the periderm is delayed will have extended endodormancy that can be ended to induce tuber sprouting by exogenous application of active CK to replace the missing endogenous signal. This is the exploitable concept to be proved in the project.

The prediction was tested by investigating the dormancy of potato plants with greatly reduced tuber contents of enzymes involved in the generation of CK ribosides. For speed and simplicity, the modified tubers for the proposed proof of concept work were generated using virus-induced gene silencing (VIGS) to suppress the expression of one of these enzymes. For subsequent commercial development, plants with a comparable phenotype, i.e. lower, or delayed onset, enzyme activity in the periderm, would be generated instead by conventional plant breeding from relictual genotypes that have not lost the prolonged, chill-reversible tuber endodormancy trait. Genetically modified plants were only used strictly within the confines of the lab as a means to fast track the proof of concept, which would have been impractical by any other method currently available. All the subsequent work towards the production of breeding lines would use conventional breeding methodology only.

The project objectives included:
1. Characterisation of a family of cytokinin riboside phosphorylases (PTDs) in potatoes, determining all the similar sequences encoding active enzyme expressed in different tissues, especially those involved in the formation and sprouting of tubers. The aim was to obtain information on the number and type of PTD genes necessary for selective breeding in subsequent phases of the project.
2. Monitoring virus-induced gene silencing (VIGS) of a cytokinin riboside phosphorylase (PTD) in tubers already generated in soil by measuring the abundance of PTD transcripts, PTD protein and cytokinin ribosides, relative to tubers from control plants so as to confirm the effectiveness of silencing.
3. Characterising the general phenotype of tubers harvested from pot-cultured potato plants in which the content of has been lowered by virus-induced gene silencing, and specifically to measure the duration of endodormancy so as to test the prediction that tubers with a lower content of the enzyme have a phenotype altered only in that the duration of endodormancy is prolonged relative to that of controls with the normal content of enzyme.
4. Examination of the effect of dormancy-breaking treatments on tubers deficient in cytokinin riboside phosphorylase, specifically cytokinins and ethanol, so as to test the prediction that any prolongation of the duration of dormancy will be effectively reduced or eliminated by these treatments
Time-Scale and Cost
From: 2007

To: 2008

Cost: £42,468
Contractor / Funded Organisations
University - Cambridge, Greenvale AP PLC, Cygenta Potato Breeder Ltd
Keywords
Arable              
LINK Programme              
Organic Farming              
Potatoes              
Sustainable Farming and Food              
Sustainable Farming and Food Science              
Sustainable Farming Systems