Inhibition of ethylene-induced -farnesene synthase gene PcAFS1 expression in ‘d’Anjou’ pears with 1-MCP reduces synthesis and oxidation of -farnesene and delays development of superficial scald

Pre-storage treatment of superficial scald-susceptible apple and pear fruits with the blocker of ethylene action 1-methylcyclopropene (1CP) inhibits the synthesis of -farnesene. Consequently, accumulation of -farnesene and its conjugated trienol (CTol) oxidation products n the fruit skin is diminished, and scald is largely prevented. In cold-stored apple fruit, a marked increase in expression of AFS1, the gene ncoding -farnesene synthase (AFS), precedes the rapid accumulation of -farnesene. A Pyrus communis L. gene encoding AFS (PcAFS1) as cloned using RT-PCR with primers based on apple AFS1 and RNA from peel tissue of ‘d’Anjou’ pears cold-stored for 33–94 days. on-treated control and 1-MCP-treated (300 nL L−1 for 6 h at 1 ◦C) pears were stored at −1 ◦C in air for up to 216 days. PcAFS1 expression n control fruit increased sharply over the first 63 days, remained high through 123 days, fell to much lower levels from 157 to 183 days, hen increased again to maximum levels at 216 days. In comparison, expression of PcAFS1 was attenuated in 1-MCP-treated fruit. PcAFS1 ranscript was almost nil through 94 days, rose sharply at 123 days and reached a maximum at 183 days that was two-fold lower than the highest evel in controls. Maximum concentrations of -farnesene and CTols in control fruit occurred at 94 and 123 days, respectively, and scald ncidence was 100% after 94 days. -Farnesene and CTol levels at these time points were, respectively, 9and 19-fold lower in 1-MCP-treated ruit, which had no scald at 157 days, 13% at 183 days and 40% at 216 days. Post-storage ripening, with the associated increases in softening, espiration and ethylene production, was fully enabled in control fruit after 63 days at −1 ◦C, whereas 1-MCP-treated pears failed to ripen roperly even after 216 days. ublished by Elsevier B.V.