Physiological, Biochemical, and Molecular Changes in Pelargonium Cuttings Subjected to Short-term Storage Conditions

Abstract

The purpose of this study was to evaluate physiological, biochemical and molecular changes which occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper), and `Snowmass' (poor shipper) were stored at 25°C and evaluated over a 5-day period. Following removal from storage, cuttings exhibited progressive declines in photosynthesis, respiration, carbohydrate, starch and protein over time which was significant in all three cultivars, however there was little difference among the cultivars. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following the initiation of storage, whereas `Snowmass' showed an increase after one day reaching a peak at 3 days and was followed by a sharp decline. When unrooted cuttings of `Snowmass' were stored for a 5-day period at temperatures from 4 to 25°C, it was observed that those stored at 4°C had a significantly higher visual rating, chlorophyll content, root and shoot weight than at higher temperatures tested. The decline in quality progressively became greater from 10 to 25°C. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings which were stored at 4 and 25°C. Correlations between ethylene and ACC levels with gene expression were observed.