ISHS Acta Horticulturae 682: V International Postharvest Symposium
FARNESYLATION OF COMPONENTS OF THE ETHYLENE SIGNALING PATHWAY MAY BE NECESSARY TO THE DEVELOPMENT OF SUPERFICIAL SCALD IN APPLES |
| Authors: | M.M. Haines, D.S. Mattinson, J.K. Fellman |
| Keywords: | Malus × domestica, α-farnesene, farnesyl protein transferase, nitrone spin trap, conjugated trienol hydroperoxides, 1-methylcyclopropene, farnesyl transferase inhibitors, apoptosis |
| Abstract:
Superficial scald is a severe postharvest physiological disorder of apples (Malus × domestica Borkh.) that strikes apples during or after removal from cold storage. Currently, it is effectively prevented by DPA, but human health concerns may prevent reregistration. Ethylene and auto-oxidation products (radicals) of α-farnesene are implicated in scald development. Ethylene signaling proceeds via CTR1, a MAPK that may require farnesylation via FPT for activity. ‘Granny Smith’ apples were treated with 1-MCP and FPTI to block ethylene action and farnesylation, respectively, and stored under RA or CA (1% O2) conditions for 7-8 months. After seven days at 19°C, apples treated with MCP showed low scald (RA) or no scald (CA). RA and FPTI-treated apples scalded similarly. Ethylene and farnesene production was highest in CA controls, lowest in CA-MCP apples. Conjugated trienols were highest in CA controls and FPTI apples, while radicals were highest in FPTI-treated apples, followed by CA controls. FPTI-treated apples showed 15% lower respiration than RA, and exhibited cortical tissue softening, both likely due to apoptotic effects of FPT inhibition. Peel protein extracts showed the presence of FPT protein in all samples, thus CTR1 farnesylation remains equivocal and needs further study. CA-MCP apples were lowest in all evaluated components, and should be investigated for texture, flavor, and aroma volatile production to develop an effective marketing strategy. | |
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