Physiological, biochemical, and molecular changes in Pelargonium cuttings subjected to short-term storage conditions

The purpose of this study was to evaluate physiological, biochemical, and molecular changes that occur in unrooted Pelargonium xhortorum 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 of all cultivars exhibited steady and significant decline in photosynthesis, respiration, carbohydrate, starch, and protein over time. However, no significant differences were observed among cultivars for all of these parameters. Ethylene levels produced by 'Sincerity' and 'Wendy Ann' began to increase 3 days following storage; whereas, 'Snowmass' showed an increase after 1 day, reaching a peak at 3 days, and then declined. When unrooted cuttings of 'Snowmass' were stored for 5 days at temperatures ranging from 4 to 25 °C, it was observed that those stored at 4 °C had a significantly higher visual rating, chlorophyll content, and root and shoot weight than at higher temperatures tested. As temperature increased from 10 to 25 °C, quality of cuttings declined. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in 'Snowmass' cuttings stored at 4 and 25 °C. Correlations between ethylene and ACC levels with gene expression were observed. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).