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Fig. 3 | BMC Plant Biology

Fig. 3

From: Plant-mediated RNAi silences midgut-expressed genes in congeneric lepidopteran insects in nature

Fig. 3

Silencing of midgut-expressed CYP6B46 and BG1 genes in wild M. quinquemaculata larvae feeding on WT, PMRi, and nicotine and DTG-depleted plants. a Wild Manduca spp. eggs oviposited on Datura wrightii provided the source of M. quinquemaculata larvae which can be distinguished from M. sexta larvae when the larvae reach the third- instar. b PMRi N. attenuata lines and N. attenuata plants transformed by RNAi to silence: nicotine biosynthesis, by expressing an inverted repeat (ir) construct of the host plant’s putrescine N-methyl transferase (irPMT) and 17-hydroxygeranyllinalool diterpene glycoside (HGL-DTGs) biosynthesis, by expressing an ir construct of geranylgeranyl pyrophosphate synthase (irGGPPS); planted in a field plot in Great Basin Desert of southwestern Utah. c M. quinquemaculata CYP6B46 transcripts (relative to ubiquitin) in various tissues of fourth-instar larvae fed on EV, irCYP6B46 and irPMT plants (midgut: F 2,15  = 7.219 P ≤ 0.006; hindgut: F 2,15  = 6.651 P ≤ 0.008; Malpighian tubules: F 2,15  = 10.604 P ≤ 0.001; n = 6 in all bars). Note that feeding on nicotine-containing WT plants strongly induces the midgut expression of CYP6B46 transcripts and that feeding on the PMRi plants which contain WT levels of nicotine deplete CYP6B46 transcript abundance to levels found in larvae feeding on nicotine-depleted irPMT plants. d M. quinquemaculata BG1 transcripts (relative to ubiquitin) in various tissues of fourth-instar larvae feeding on EV, irBG1 and irGGPPS plants (midgut: F 2,14  = 9.458 P ≤ 0.002; n = 6 in EV, GGPPS and 5 in BG1 group). Note that feeding on HGL-DTG-containing WT plants strongly induces the midgut expression of BG1 transcripts and that feeding on the PMRi plants which contain WT levels of HGL-DTGs deplete BG1 transcript abundance to levels found in larvae feeding on HGL-DTG-depleted irGGPPS plants. Asterisks indicate significant differences between means (± SE) in comparison to EV, determined by one-way ANOVA and Fisher LSD post hoc, which was conducted separately for each tissue

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