Transcriptome and Metabolome Analyses of Glucosinolates in Two Broccoli Cultivars Following Jasmonate Treatment for the Induction of Glucosinolate Defense to Trichoplusia ni (Hübner)

Abstract

Lepidopteran larvae growth is influenced by host plant glucosinolate (GS) concentrations, which are, in turn, influenced by the phytohormone jasmonate (JA). In order to elucidate insect resistance biomarkers to lepidopteran pests, transcriptome and metabolome analyses following JA treatments were conducted with two broccoli cultivars, Green Magic and VI-158, which have differentially induced indole GSs, neoglucobrassicin and glucobrassicin, respectively. To test these two inducible GSs on growth of cabbage looper (Trichoplusia ni), eight neonate cabbage looper larvae were placed onto each of three plants per JA treatments (0, 100, 200, 400 µM) three days after treatment. After five days of feeding, weight of larvae and their survival rate was found to decrease with increasing JA concentrations in both broccoli cultivars. JA-inducible GSs were measured by high performance liquid chromatography. Neoglucobrassicin in Green Magic and glucobrassicin in VI-158 leaves were increased in a dose-dependent manner. One or both of these glucosinolates and/or their hydrolysis products showed significant inverse correlations with larval weight and survival (five days after treatment) while being positively correlated with the number of days to pupation. This implies that these two JA-inducible glucosinolates can influence the growth and survival of cabbage looper larvae. Transcriptome profiling supported the observed changes in glucosinolate and their hydrolysis product concentrations following JA treatments. Several genes related to GS metabolism differentiate the two broccoli cultivars in their pattern of transcriptional response to JA treatments. Indicative of the corresponding change in indole GS concentrations, transcripts of the transcription factor MYB122, core structure biosynthesis genes (CYP79B2, UGT74B1, SUR1, SOT16, SOT17, and SOT18), an indole glucosinolate side chain modification gene (IGMT1), and several glucosinolate hydrolysis genes (TGG1, TGG2, and ESM1) were significantly increased in Green Magic (statistically significant in most cases at 400 µM) while UGT74B1 and MYB122 were significantly increased in VI-158. Therefore, these metabolite and transcript biomarker results indicate that transcriptome profiling can identify genes associated with the formation of two different indole GS and their hydrolysis products. Therefore, these metabolite and transcript biomarkers could be useful in an effective marker-assisted breeding strategy for resistance to generalist lepidopteran pests in broccoli and potentially other Brassica vegetables.

Development of a Simple Method for Determination of Anti-cancer Component of Indole-3-carbinol in Cabbage and Broccoli

“…In the process of indole-3-carbinol hydrolysis, myrosinase played a key role in the composition and amount of indole-3-carbinol in Brassica, similarly with sulforaphane hydrolyzed from glucoraphanin [31,32]. Myrosinase is affected by genotype, pH, temperature, ferrous ion, zinc and magnesium concentration, which is still a complex problem in the stability of myrosinase [19,33].…”

Targeted Metabolomic and Transcriptomic Analyses of “Red Russian” Kale (Brassicae napus var. pabularia) Following Methyl Jasmonate Treatment and Larval Infestation by the Cabbage Looper (Trichoplusia ni Hübner)

“…Greater concentrations of indolyl GS were observed to enhance insect deterrence. In ‘Green Magic’ and ‘VI-158’ broccoli cultivars, the survival rate and the larval weight of cabbage looper ( Trichoplusia ni ) has been found to be significantly reduced by a 400 μM spray application of JA, attributable to the increase of neoglucobrassicin (indolyl GS) concentration [ 30 ].…”

“…In contrast, insect herbivory may be a gradual and more complicated process, since the plants are simultaneously challenged by physical wounding and foreign peptides from the insect’s saliva. Although previous research has focused on how GS affects insect herbivory in Arabidopsis mutant lines or other Brassica crops [ 21 , 23 , 30 , 44 ], how exogenously applied MeJA alters metabolite concentrations and how its effects differ from those of the actual insect herbivore on plants remain unclear. To determine the potential differences in the biochemical responses, in this study, we compare the changes in GS, GSHP, and primary metabolite concentrations in plants of “Red Russian” kale undergoing insect damage (leaf tissue 4 days after infestation of Trichoplusia ni larvae) or MeJA spray treatment (leaf tissue harvested 4 days after 250 µM MeJA treatment).…”

Effect of methyl jasmonate (MeJA)‐induced defenses in rice against the rice leaffolderCnaphalocrocis medinalis(Guenèe) (Lepidoptera: Pyralidae)

“…When applied topically, jasmonate extracts have been shown to induce plant natural defense reactions . JA and its associated chemicals trigger signal transduction pathways that influence several genes to express encoding for defensive proteins …”