Location: Plant Physiology and Genetics ResearchTitle: Fruit cuticle lipid composition and fruit post-harvest water loss in an advanced backcross generation of pepper (Capsicum sp.)) Author
Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2011
Publication Date: 7/12/2012
Citation: Parsons, E.P., Popopvsky, S., Lohrey, G.T., Lu, S., Alkalai-Tuvia, S., Perzelan, Y., Paran, I., Fallik, E., Jenks, M.A., 2012. Fruit cuticle lipid composition and fruit post-harvest water loss in an advanced backcross generation of pepper (Capsicum sp.). Physiologia Plantarum, DOI:10.1111/j.1399-3054.2012.01592.x. Interpretive Summary: A unique genetics-based approach was taken to evaluate the role of cuticle lipids, both waxes and cutin monomers, in plant water loss. Two parental lines of Capsicum, Capsicum annuum and Capsicum chinensis, showing highly divergent cuticle lipids and water loss traits in their fruits were hybridized and their progeny backcrossed to the BC2F2 population. This unique near-isogenic population was used to associate variation in wax and cutin monomer chemical composition in the fruits with water loss by fruits. Our results revealed that the more triterpenoid plus sterol compounds present in the wax the higher the water loss rate, whereas the more alkanes and aliphatics in total wax the lower the water loss rate. In cutin, we found that the more total C16 monomers and 16-dihydroxy hexadecanoic acid, the higher the water loss rate. Our results support the hypothesis that simple straight-chain aliphatic cuticle constituents form more impermeable cuticular barriers than more complex isoprenoid-based compounds, and shed new light on the biochemical basis for cuticle involvement in fruit water loss.
Technical Abstract: During postharvest storage, pepper (Capsicum sp.) fruit commonly wilts (or shrivels) early because of rapid water loss combined with the hollow fruit’s limited water storage capacity, a condition that greatly reduces its shelf-life and market value. To understand the role of fruit cuticle lipid composition in fruit water loss, an advanced back-cross population, the BC2F2, was created between the C. annuum (PI1154) and the C. chinense (USDA162) which have high and low postharvest water loss rates respectively. Besides dramatic differences in fruit water loss, preliminary studies also revealed that these parents exhibited significant differences in both the amount and composition of their fruit cuticle. Cuticle analysis of the BC2F2 fruit revealed that although water loss rate was not strongly associated with the total wax amount, there were significant correlations between water loss rate and cuticle composition. We found a positive correlation between water loss rate and the amount of total triterpenoid plus sterol compounds, and negative correlations between water loss and the alkane to triterpenoid plus sterol ratio. We also report negative correlations between water loss rate and the proportion of both alkanes and aliphatics to total wax amount. In cutin we found positive associations of water loss rate with total cutin, total C16 monomers and with the 16-dihydroxy hexadecanoic acid. Our results support the hypothesis that simple straight-chain aliphatic cuticle constituents form more impermeable cuticular barriers than more complex isoprenoid-based compounds. These results shed new light on the biochemical basis for cuticle involvement in fruit water loss.