Abstract
Iminosugars are carbohydrate mimics that are useful as molecular probes to dissect metabolism in plants. To analyse the effects of iminosugar derivatives on germination and seedling growth, we screened a library of 390 N-substituted iminosugar analogues against Arabidopsis and the small cereal Eragrostis tef (Tef). The most potent compound identified in both systems, N-5-(adamantane-1-yl-ethoxy)pentyl- l-ido-deoxynojirimycin (l-ido-AEP-DNJ), inhibited root growth in agar plate assays by 92% and 96% in Arabidopsis and Tef respectively, at 10 µM concentration. Phenocopying the effect of l-ido-AEP-DNJ with the commercial inhibitor (PDMP) implicated glucosylceramide synthase as the target responsible for root growth inhibition. l-ido-AEP-DNJ was twenty-fold more potent than PDMP. Liquid chromatography-mass spectrometry (LC-MS) analysis of ceramide:glucosylceramide ratios in inhibitor-treated Arabidopsis seedlings showed a decrease in the relative quantity of the latter, confirming that glucosylceramide synthesis is perturbed in inhibitor-treated plants. Bioinformatic analysis of glucosylceramide synthase indicates gene conservation across higher plants. Previous T-DNA insertional inactivation of glucosylceramide synthase in Arabidopsis caused seedling lethality, indicating a role in growth and development. The compounds identified herein represent chemical alternatives that can overcome issues caused by genetic intervention. These inhibitors offer the potential to dissect the roles of glucosylceramides in polyploid crop species.
Highlights
Plant carbohydrate metabolic processes, including starch, cell wall, glycolipid and glycoprotein synthesis and degradation, are essential to seedling establishment and have implications for crop quality, utilisation and pathogen resistance[1,2,3]
To identify novel inhibitors and determine the effect that derivatives of DNJ have on germination and seedling growth, we blind-screened a collection of 390 iminosugar derivatives, at a concentration of 10 μM, in agar plate based Arabidopsis root growth assays
We found PDMP to give much stronger inhibition compared to the more lipophilic PPMP (Figs 4a–c and S4a,b); PPMP gave no significant inhibition of root growth with Arabidopsis or Tef whereas PDMP showed significant inhibition of root growth at concentrations of 20 μM for Arabidopsis and 10 μM for Tef
Summary
Plant carbohydrate metabolic processes, including starch, cell wall, glycolipid and glycoprotein synthesis and degradation, are essential to seedling establishment and have implications for crop quality, utilisation and pathogen resistance[1,2,3]. Three compounds (1-deoxynojirimycin [DNJ], N-butyl-1-deoxynojirimycin [N-Bu-DNJ] and Miglitol, Fig. 1-1, 2 & 3) gave over 80% inhibition of α-glucosidase activity at 10 μM These inhibitors were further tested on germinating barley and shown to inhibit α-glucosidase activity, decrease grain starch metabolism and retard root growth. RNAi suppression of the single gene encoding GCS enabled the generation of viable plants with ≤2% of wild type GlcCer levels indicating that only low levels of this enzyme are needed for cell differentiation, organ development and seedling establishment[5]. It remains unclear why GCS activity is essential for development and why its absence cannot be complemented by other metabolic pathways
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
