Study : Hormone and transcriptome profiling in aerial tissues derived from crown buds of glyphosate treated leafy spurge


Hormone and transcriptome profiling in aerial tissues derived from crown buds of glyphosate treated leafy spurge
Glyphosate is known to inhibit 5-enolpyruvylshikimate-3-phosphate synthase of the chorismate biosynthetic pathway, and chorismate is a precursor to aromatic amino acids, auxin, and many other secondary products. Although the perennial weed leafy spurge (Euphorbia esula L.) is considered glyphosate tolerant, glyphosate is often used as part of an integrated pest management program in non-cultivated ecosystems of North America. Part of its tolerance is attributed to escape through an abundance of underground adventitious buds (UABs). Sub-lethal concentrations of foliar applied glyphosate leads to new shoot growth from UABs that have a stunted and/or bushy phenotype after growth-inducing decapitation. To gain insights into glyphosate’s impact on molecular mechanisms associated with the stunted and bushy phenotype, we obtained global transcriptome abundance using RNAseq from a subsequent generation of aerial shoots derived from crown buds of glyphosate-treated and -untreated leafy spurge. We further correlated transcript abundance to accumulation of shikimate and phytohormones from the same samples to elucidate interactions. Abundance of shikimate was similar in subsequent generations of aerial shoots generated from crown buds of treated and untreated plants and is likely not a direct factor leading to the stunted and bushy phenotype. However, the results do suggest that transcripts involved in auxin transport and signaling and crosstalk with other phytohormones likely play a role in the bushy phenotype. The results of this study provide some insights for identifying new targets for manipulation of plant growth and development. Overall design: Transcriptome and metabolite profiling are obtained for aerial tissues derived from crown buds of foliar glyphosate-treated and control (2.24 or 0 kg/ha active ingredient glyphosate + 0.25% v/v surfactant) leafy spurge plants. Each experiment included 4 biological replicates.


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