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Increased chalcone synthase (CHS) expression is associated with dicamba resistance in Kochia scoparia
Author(s) -
Pettinga Dean J,
Ou Junjun,
Patterson Eric L,
Jugulam Mithila,
Westra Philip,
Gaines Todd A
Publication year - 2018
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4778
Subject(s) - dicamba , chalcone synthase , auxin , biology , chromosomal translocation , biochemistry , gene , gene expression , agronomy , weed control
BACKGROUND Resistance to the synthetic auxin herbicide dicamba is increasingly problematic in Kochia scoparia . The resistance mechanism in an inbred dicamba‐resistant K. scoparia line (9425R) was investigated using physiological and transcriptomics (RNA‐Seq) approaches. RESULTS No differences were found in dicamba absorption or metabolism between 9425R and a dicamba‐susceptible line, but 9425R was found to have significantly reduced dicamba translocation. Known auxin‐responsive genes ACC synthase ( ACS ) and indole‐3‐acetic acid amino synthetase ( GH3 ) were transcriptionally induced following dicamba treatment in dicamba‐susceptible K. scoparia but not in 9425R. Chalcone synthase ( CHS ), the gene regulating synthesis of the flavonols quertecin and kaemperfol, was found to have twofold higher transcription in 9425R both without and 12 h after dicamba treatment. Increased CHS transcription co‐segregated with dicamba resistance in a forward genetics screen using an F 2 population. CONCLUSION Prior work has shown that the flavonols quertecin and kaemperfol compete with auxin for intercellular movement and vascular loading via ATP‐binding cassette subfamily B (ABCB) membrane transporters. The results of this study support a model in which constitutively increased CHS expression in the meristem produces more flavonols that would compete with dicamba for intercellular transport by ABCB transporters, resulting in reduced dicamba translocation. © 2017 Society of Chemical Industry