The CTR and EIN gene are involved directly in
transducing the ethylene receptor signal (Seymour et al., 2013).
SlEIN/EIL1 and three genes were up-regulated by exogenous
melatonin, whereas the expression of SlCTR1 and SlEIN/EIL2
was almost unresponsive to melatonin treatment (Fig. 5C).
Ethylene response factor (ERF) is a well-known transcriptional
regulator involved in controlling ethylene responses (Seymour
et al., 2013). In our study, SlERF2 was highly up-regulated by
2.5-fold under melatonin treatment (Fig. 5C).
In this study, we observed that the climacteric peak of
melatonin-treated samples occurred earlier, and ethylene
production was increased compared with CK (Fig. 5A).
Furthermore, at the climacteric peak time under 50 μM
melatonin treatment, the expression of ethylene biosynthesis-
related gene (SlACS4), ethylene receptor genes (SlNR
and SlETR4), and ethylene signalling-related genes (SlEIL1,
SlEIL3, and SlERF2) were up-regulated to varying degrees.
Taken together, these results indicate that melatonin may
affect the ethylene production by control of gene expression
on ethylene biosynthesis and signal transduction pathway.