Transcriptome responses to the phytotoxin t-Chalcone in Arabidopsis thaliana L.

Authors: DIAZ-TIELAS, CARLA - University Of Vigo; GRANA, ELISA - University Of Vigo; SANCHEZ-MOREIRAS, ADELA - University Of Vigo; REIGOSA, MANUEL - University Of Vigo; Vaughn, Justin; Pan, Zhiqiang - Peter; Bajsa-Hirschel, Joanna; Duke, Stephen

Submitted to: Society of Chemical Industry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2019
Publication Date: 3/13/2019
Citation: Diaz-Tielas, C., Grana, E., Sanchez-Moreiras, A.M., Reigosa, M.J., Vaughn, J.N., Pan, Z., Bajsa Hirschel, J.N., Duke, S.O. 2019. Transcriptome responses to the phytotoxin t-Chalcone in Arabidopsis thaliana L. Pest Management Science. https://doi.org/10.1002/ps.5405.
DOI: https://doi.org/10.1002/ps.5405

Interpretive Summary: New, environmentally safe natural product-based herbicides are desired, and new herbicide modes of action are needed to combat herbicide resistance in weeds. The paper describes research to further develop the plant-produced compound t-chalcone as a herbicide and to discover its mode of action. Its unique mode of action was probed by determining its effects on expression of the plant genome (the transcriptome). Evidence is provided that supports the view that t-chalcone is converted within the target plant to an inhibitor of the enzyme p-hydroxyphenypyruvate dioxygenase, a well established herbicide target.

Technical Abstract: Although an intermediate in flavonoid synthesis, t-chalcone is phytotoxic, causing mitochondrial disruption and apoptosis-like symptoms in plant roots and causing bleaching of normally green shoot tissues. These phenomena suggest a unique mode of action. Using RNA-Seq, we report the transcriptome changes in Arabidopsis seedlings during the first 24 h of exposure (at 1, 3, 6, 12 and 24 h) to 21 µM t-chalcone (I50 dose), examining effects on Arabidopsis roots and shoots separately. Using a confidence of p = 0.01 and fold changes of = 2.00, expression of 892 and 1000 genes was affected in roots and shoots, respectively. In the roots, there was a general pattern of up- and down-regulation for the first 6 h after exposure, with much less effect at 12 and 24 h. In the shoots, there were fewer effects for the first 3 h, followed by stronger effects at 6-24 h. According to biological function, the affected genes were mainly transcription factors and genes associated with oxidative stress, heat shock proteins, xenobiotic detoxification, and ABA and auxin biosynthesis. Genes in the root associated with programmed cell death were up-regulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated several potential primary metabolism enzymatic target sites. Of these, p-hydroxyphenylpyruvate dioxygenase (HPPD) and tyrosine amino transferase were consistent with the bleaching effect of the phytotoxin on Arabidopsis. Supplementation studies with duckweed and arabidiopsis supported HPPD as the target, although in vitro enzyme inhibition was not found. Thus, t-chalcone is possibly a protoxin that is converted to a HPPD inhibitor in vivo.