Methyl Jasmonate Increases Glucobrassicin Concentration In Brassica oleracea Var. Capitata ‘Quisto' and ‘Ruby Perfection'

Glucosinolates are generally thought to act in planta as feeding deterrents to generalist herbivores and as oviposition or feeding signals for specialist herbivores.  Chewing herbivory and wounding in cruciferous vegetables causes the plants to synthesize glucosinolates through a jasmonate-depending signaling cascade.  Exogenous jasmonate application can enhance accumulation of defensive metabolites, including glucosinolates.  Glucobrassicin is an indole glucosinolate in cruciferous vegetables that is hydrolyzed to the chemopreventive indole-3-carbinol during consumption and digestion.  The objective of this research was to study delayed effects of methyl jasmonate (MeJA) on glucosinolate concentration in cabbage with different baseline concentrations of glucobrassicin.  ‘Quisto’ and ‘Ruby Perfection’ cabbage were grown in a split-plot design on raised beds and sprayed with water, surfactant + solvent in water, or surfactant + solvent + 0.5 mM MeJA at 2, 6, or 2 + 6 days before harvest.  ‘Quisto’ contained less glucobrassicin than ‘Ruby Perfection’ on a fresh weight basis, but ‘Quisto’ head fresh weight was greater.  MeJA applied 2 days before harvest slightly increased glucobrassicin concentration in ‘Ruby Perfection’ but not ‘Quisto’.