Methyl jasmonate, salicylic acid and abscisic acid enhance the accumulation of glucosinolates and sulforaphane in radish (Raphanus sativus L.) taproot

Abstract Radish is an important root vegetable crop. The effects of environmental stresses on glucosinolate (GLS) contents were extensively investigated in Brassicaceae species. However, little is known about the accumulation of GLS and sulforaphane (SF) in hormone-treated radish taproot. In this study, the effects of methyl jasmonate (MeJA), salicylic acid (SA) and abscisic acid (ABA) on the accumulation of GLS and SF in radish taproot were investigated. The GLS content increased considerably in response to MeJA treatment. Moreover, MeJA also up-regulated the expression level of several transcription factors and GLS biosynthesis related genes. The effects of SA on GLS content were less obvious, while ABA suppressed GLS biosynthesis. Additionally, the SF content increased under treatments with MeJA, SA and ABA. Furthermore, changes in myrosinase activity and glucoraphanin (GRA) content after the application of MeJA, SA and ABA were consistent with the changes in SF contents. The results indicated that the MeJA represents one of the most effective plant growth regulators (PGRs) for increasing the GLS content in radish taproot by up-regulating the expression levels of a few GLS biosynthetic related genes. These findings also implied that SF formation is correlated with myrosinase activity and GRA content in radish taproot.