Reducing energy usage and wastage by improving ethylene control of potato sprouting

James Hutton Institute, Cygnet Potato breeders, Greenwich University Enterprise, Landseer Ltd, Natural Resources Institute, Pepsico International, Scottish Greenvale AP.

Genetic and molecular basis of varietal sensitivity to ethylene

A range of genotypes resulting from the cross between well characterized parents (12601 ab1 and Stirling) were studied over two seasons. The parents were known to show differences in sprout growth response to ethylene. Overall, the sprout growth shown by the parents and progeny across seasons indicates a strong environmental contribution to the ethylene response.

The genotypes were used to try and understand the genetic architecture of the responses to ethylene. Ideally, the techniques used would provide information concerning the number of genes that strongly influence the response to ethylene and the chromosomal location of the genes. Although several stretches of DNA were identified as being associated with sprouting in air or in ethylene the results indicate that a large number of genes are involved in the plant’s response to ethylene.   A complementary approach has led to the identification of genes which showed significant differential expression between air and ethylene treatments between the genotypes. This has resulted in a manageable number of key genes being identified which may warrant further study.

Evaluation of other sprout control options

During the project several chemicals were tested for their synergistic behaviour with ethylene treatment to determine whether a combined treatment could provide a more reliable strategy for sprout control than ethylene alone.

The effectiveness of ethylene treatment is variety dependent, and the varieties studied have been categorised into three groups: Markies, Russet Burbank and Sylvana being very responsive (Group A), with Cabaret, Maris Piper (Group B), Hermes and Saturna (Group C) less responsive. Ethylene has a detrimental effect on processing quality but the extent of this varies with variety. This is independent of the effect on sprouting

Following small-scale trials, larger scale trials were conducted on the use of R-carvone or 1-methyl cylopropene (1-MCP; SmartFresh^TM), to improve sprout control and processing quality, respectively

SmartFresh^TM had no effect on sprouting behaviour but helps to ameliorate the ethylene-induced sugar accumulation in some varieties early in the storage season for up to 2 months.

R-carvone (spearmint oil) had little or no apparent effect on processing quality for all varieties. For varieties that are unresponsive to ethylene the addition of spearmint oil improves sprout control. For some varieties there is a strong additive effect on sprout control for tubers treated with both ethylene and spearmint oil, while for others (Saturna and Hermes) the additive effect of spearmint on sprout growth is less pronounced

A range of other chemicals were studied and 1,4 dimethylnaphthalene (1,4 DMN) and methyl jasmonate have been identified has having most potential in the medium-term, and several other Plant Growth Regulators have been identified as of longer-term interest.