SIMYC2 Involved in Methyl Jasmonate-Induced Tomato Fruit Chilling Tolerance

MYC2, a basic helix loop helix transcription factor, is a master regulator in Jasmonic acid (JA) signaling pathway. However, the functions of S1MYC2 in methyl jasmonate (MeJA)-mediated fruit chilling tolerance are far from being clearly understood. Thus, in the present work, we constructed SIMYC2-silenced tomato fruit by virus-induced gene silencing (VIGS) and investigated the function of S1MYC2 in MeJA-induced tomato fruit chilling tolerance. The results showed that MeJA treatment markedly induced the S1MYC2 expression; increased proline content, lycopene content, and antioxidant enzyme activities, including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase; inhibited the increase of electrical conductivity and malondialdehyde content; and effectively reduced the chilling injury (CI) incidence and CI index. However, these effects of MeJA treatment were partially counteracted in SIMYC2-silenced tomato fruit, and the CI incidence and CI index in (S/MYC2-silenced + MeJA)-treated fruit were higher than those in MeJA-treated fruit. Our results indicated that S1MYC2 might be involved in MeJA-induced chilling tolerance, possibly by ameliorating the antioxidant enzyme system of fruit and increasing proline and lycopene levels.