Glucosinolates are
nitrogen and
sulfur containing secondary metabolites found mainly in the Brassicaceae. They function as plant defense compounds against a broad spectrum of pathogens and pests. Since these molecules form part of the plant defense mechanism,
glucosinolate biosynthesis may be modulated by environmental signals leading to activation of a biological stress response. In the current study, we have mimicked such conditions by exogenously applying biotic elicitors such as
methyl jasmonate,
salicylic acid,
glucose and mechanical injury in Brassica juncea seedling over a time course experiment. We found that total
glucosinolates over-accumulated under these stress conditions with maximum accumulation observed 24h post treatment.
Indole glucosinolates like 1-methoxy-indol-3-ylmethyl and its precursor indol-3-methyl
glucosinolates showed a more significant induction compared to aliphatic
glucosinolates thereby suggesting a prominent role of
indole glucosinolates during plant defense response in B. juncea seedlings. In contrast, the higher amounts of aliphatic
glucosinolates were less regulated by the tested biotic elicitors in B. juncea. Expression profiling of multiple homologs of key transcriptional regulators of
glucosinolate biosynthesis further showed that a complex interplay of these regulators exists in
polyploid B. juncea where they exert co-ordinated and overlapping effects toward altering
glucosinolate accumulation. This study has a significant role toward understanding and augmenting plant defense mechanisms in B. juncea, a globally important oilseed crop of genus Brassica.