An in-frame deletion mutation in the degron tail of auxin coreceptor <i>IAA2</i> confers resistance to the herbicide 2,4-D in <i>Sisymbrium orientale</i>
Marcelo Rodrigues Alves de Figueiredo, Anita Küpper, Jenna Malone, Tijana Petrović, Ana Beatriz T. B. de Figueiredo, Grace Campagnola, Olve B. Peersen, Kasavajhala V. S. K. Prasad, Eric L. Patterson, Anireddy S. N. Reddy, Martin Kubeš, Richard Napier, Franck E. Dayan, Christopher Preston, Todd A. Gaines
Abstract
Significance Synthetic auxin herbicides intersect basic plant developmental biology and applied weed management. We investigated resistance to 2,4-D in the Australian weed Sisymbrium orientale (Indian hedge mustard). We identified a mechanism involving an in-frame 27-bp deletion in the degron tail of auxin coreceptor IAA2, one member of the gene family of Aux/IAA auxin co-receptors. We show that this deletion in IAA2 is a gain-of-function mutation that confers synthetic auxin resistance. This field-evolved mechanism of resistance to synthetic auxin herbicides confirms previous biochemical studies showing the role of the Aux/IAA degron tail in regulating Aux/IAA protein degradation upon auxin perception. The deletion mutation could be generated in crops using gene-editing approaches for cross-resistance to multiple synthetic auxin herbicides.