FIGURE 3.

Impact of plant myrosinase activity on allyl glucosinolate sequestration in P. armoraciae. Adult beetles were fed with allyl glucosinolate-spiked Arabidopsis leaves with (wild type) and without (tgg) myrosinase activity for 1 day (n = 6–7 per plant genotype). (A) Headspace volatiles were collected on Porapaq-Q^TM adsorbent, eluted with hexane, and analyzed by gas chromatography-mass spectrometry. The amounts of emitted allyl isothiocyanate (AITC; m/z 99) were quantified using an external standard curve. Detected AITC amounts were corrected by subtracting the background emission detected in volatile collections performed without beetles, which served as controls. AITC amounts were compared by Mann-Whitney rank sum test (***p < 0.001). (B) The amounts of sequestered allyl glucosinolate in beetles were quantified after conversion to desulfo-glucosinolate using an internal standard by HPLC-DAD. The amounts of allyl glucosinolate were compared by Student’s t-test and were not significantly different (n.s., p > 0.05). Results of statistical analyses are provided in Supplementary Table 1.