|GRAMIG, GRETA - North Dakota State University|
Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2015
Publication Date: 1/14/2016
Citation: Dogramaci, M., Gramig, G.G., Anderson, J.V., Chao, W.S., Foley, M.E. 2016. Field application of glyphosate induces molecular changes affecting vegetative growth processes in leafy spurge. Weed Science. 64(1):87-100. https://doi.org/10.1614/WS-D-15-00108.1.
Interpretive Summary: Leafy spurge is an invasive perennial weed infesting non-cultivated areas in the Great Plains of the US and Canada. Long term control of leafy spurge requires continual herbicide applications because the plant reproduces vegetatively from abundant underground buds. We are investigating the effects of sublethal glyphosate rates on vegetative growth from underground buds of leafy spurge under natural field conditions. Sublethal rates of glyphosate-treatment affected vegetative shoot growth from underground buds of leafy spurge at least two years after the treatment, and new shoots derived from these buds were different compare to un-treated plants. New shoots from glyphosate-treated plants had a stunted and bushy growth patterns. Further studies revealed that glyphosate-treatment affects molecular mechanisms associated with plant growth regulators such as auxin, cytokinin, ethylene, and gibberellins, and thus vegetative growth patterns from underground buds of leafy spurge.
Technical Abstract: Recommended rates of glyphosate for non-cultivated areas destroy the aboveground shoots of the perennial plant leafy spurge. However, such applications cause little or no damage to underground adventitious buds (UABs), and thus the plant readily regenerates vegetatively. High concentrations of glyphosate, applied under controlled environmental conditions, have been shown to cause sub-lethal effects in UABs of leafy spurge that produce stunted and bushy phenotypes in subsequent generations of shoots. We treated leafy spurge plants in the field with glyphosate (0, 1.1, 3.4, or 6.7 kg ai ha-1) to determine its effects on vegetative growth from UABs and on molecular processes. The number of shoots derived from UABs of glyphosate-treated plants was significantly increased compared to controls in subsequent years after application, and new shoots displayed various phenotypical changes, such as stunted and bushy phenotypes. Quantifying the abundance of a selected set of transcripts in UABs of non-treated vs. treated plants (0 vs. 6.7 kg ha-1) indicated that glyphosate impacted molecular processes involved in biosynthesis or signaling of tryptophan or auxin (ARF4, CYP79B2, PIN3, TAA1, TRP6, YUC4), gibberellic acid (GA1/CPS1, GA2/KS), ethylene (ACO1, ACS10), cytokinins (AHP1, AK2, CKX1), and the cell cycle (CDC2A, CDC2B, CYCD3;1). Glyphosate-induced effects on vegetative growth and transcript abundance were persistent for at least two years after treatment. Determining the molecular mechanisms associated with vegetative reproduction in leafy spurge following foliar glyphosate-treatment could identify limiting factors or new targets for manipulation of plant growth and development in perennial weeds.