Registration of 'Resilience CL+' soft white winter wheat

Authors: GILL, K - Washington State University; RANDHAWA, H - Lethbridge Research Center; MURPHY, K - Washington State University; CARTER, A - Washington State University; Morris, Craig; HIGGINBOTHAM, R - Washington State University; Engle, Douglas; GUY, S - Washington State University; LYON, D - Washington State University; MURRAY, T - Washington State University; Chen, Xianming; SCHILLINGER, W - Washington State University

Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2020
Publication Date: 2/12/2021
Publication URL: https://handle.nal.usda.gov/10113/7709349
Citation: Gill, K.S., Randhawa, H.S., Murphy, K., Carter, A.H., Morris, C.F., Higginbotham, R.W., Engle, D.A., Guy, S.O., Lyon, D.J., Murray, T.D., Chen, X., Schillinger, W.F. 2021. Registration of 'Resilience CL+' soft white winter wheat. Journal of Plant Registrations. 15(1):196-205. https://doi.org/10.1002/plr2.20118.
DOI: https://doi.org/10.1002/plr2.20118

Interpretive Summary: Soft white winter (SWW) is the major market class of wheat in the Pacific Northwest (PNW). In the wheat production system of PNW, annual grassy weeds including jointed goatgrass and downy brome are the most problematic, causing significant yield losses and grain dockage. The imidazolinone family of herbicides, including imazamox can effectively control grassy weeds, including jointed goatgrass, by inhibiting the enzyme involved in the biosynthesis of the branched-chain amino acids valine, leucine and isoleucine. However, imazamox cannot be used on wheat due to the presence of the form of acetolactate synthase (ALS) protein to which the herbicide can bind. Two mutant alleles (Als1 and Als2) in the ALS gene located on the long arm of group-6 chromosomes (6D and 6B) of bread wheat have been identified, which provide tolerance to imazamox herbicide. A mutation was identified in the ALS gene that stops the herbicide from binding to the protein, thus making the plant tolerant to the herbicide. This herbicide tolerance technology is marketed under the trade name ‘Clearfield®’ and ‘Clearfield® Plus’. Until the release of Resilience CL+, few wheat cultivars were present in the high rainfall zones of the PNW that carry the two-gene technology. However, cultivars carrying the single gene technology were successfully grown in the region. Usually, varieties carrying the single gene technology show yield reduction upon the application of standard imazamox rates, especially in the spray overlap areas of the field. The ‘Clearfield® Plus’ technology also allows the use of more aggressive surfactant packages, such as those including methylated seed oil (MSO), which can provide significantly better weed control than a milder surfactant like non-ionic surfactant (NIS). Resilience CL+ is a semi-dwarf soft white winter wheat that is well adapted to the high rainfall non-irrigated wheat production regions of Washington. Resilience CL+ was released as a two-gene Clearfield wheat alternative to cultivars ORCF-102 (PVP 200500337) and SY Ovation (PVP 201100387) that were widely grown in the high precipitation region in PNW at the time of the release. Resilience CL+ has soft kernels and end-use quality assessments showed good cookie diameter as well as superior sponge cake quality, similar to the standard check variety ‘Stephens’.

Technical Abstract: Resilience CL+ (PVP 201800104; PI 686413) is a soft white common winter wheat (SWW, Triticum aestivum L.) cultivar carrying two-gene tolerance to imazamox herbicide, that was developed and released in October 2016 by the Agricultural Research Center of Washington State University. It was tested under the experimental designations KCF9002 and WA008187. Resilience CL+ was developed using a marker-assisted background selection (MABS) and marker-assisted forward breeding approaches involving a cross between a soft white winter wheat cultivar ‘Madsen’ and CL0618 (an Australian hard red spring two-gene Clearfield mutant line). Resilience CL+ carries two mutation alleles (Als1 and Als2) of the acetolactate synthase gene located on the long arm of chromosomes 6D and 6B. Resilience CL+ has high grain-yield potential, intermediate plant height and is well adapted to regions of the inland Pacific Northwest (PNW) with >500 mm of annual precipitation. Resilience CL+ exhibited herbicide tolerance equivalent to ‘AP503 CL2’ and greater than the single-gene Clearfield cultivar ‘ORCF-102’. As compared to the other Clearfield cultivars grown in the PNW, Resilience CL+ has a high level of resistance to stripe rust and foot rot resistance, similar to that of Madsen. Resilience CL+ has soft kernels, excellent milling score, and good end-use quality characteristics. Yield comparison of Resilience CL+ with other popular cultivars demonstrated that it has greater yield than SY Ovation and Madsen but similar to ORCF-102.