Published online by Cambridge University Press: 20 January 2017
Long-term control of leafy spurge with glyphosate requires multipleapplications because the plant reproduces vegetatively from abundantunderground adventitious buds, referred to as crown and root buds.Determining the molecular mechanisms involved in controlling vegetativereproduction in leafy spurge following foliar glyphosate treatment couldidentify limiting factors or new targets for manipulation of plant growthand development in invasive perennial species. Thus, we treated leafy spurgeplants with 0 or 2.24 kg ai ha−1 glyphosate to determine itsimpact on selected molecular processes in crown buds derived from intactplants and plants decapitated at the soil surface 7 d after glyphosatetreatment. New shoot growth from crown buds of foliar glyphosate-treatedplants was significantly reduced compared with controls aftergrowth-inducing decapitation, and had a stunted or bushy phenotype.Quantification of a selected set of transcripts involved in hormonebiosynthesis and signaling pathways indicated that glyphosate had the mostsignificant impact on abundance of ENT-COPALYL DIPHOSPHATE SYNTHETASE 1, which is involved in a committed step forgibberellin biosynthesis, and auxin transporters including PINs, PIN-LIKES, and ABC TRANSPORTERS. Foliarglyphosate treatment also reduced the abundance of transcripts involved incell cycle processes, which would be consistent with altered growth patternsobserved in this study. Overall, these results suggest that interplay amongphytohormones such as auxin, ethylene, and gibberellins affect vegetativegrowth patterns from crown buds of leafy spurge in response to foliarglyphosate treatment.