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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #398188
Research Project: Improved Plant Genetic Resources and Methodologies for Rangelands, Pastures, and Turf Landscapes in the Semiarid Western U.S.

Location: Forage and Range Research

Title: Registration of L-74X nonshattering basin wildrye x creeping wildrye germplasm

Author
item Larson, Steven
item Jones, Thomas
item Jensen, Kevin

Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2023
Publication Date: 4/28/2023
Citation: Larson, S.R., Jones, T.A., Jensen, K.B. 2023. Registration of L-74X nonshattering basin wildrye x creeping wildrye germplasm. Journal of Plant Registrations. 17(2):397-403. https://doi.org/10.1002/plr2.20293.
DOI: https://doi.org/10.1002/plr2.20293

Interpretive Summary: Basin wildrye is somewhat indeterminate and shatters its seed when ripe. Thus, to avoid shattering losses, growers tend to harvest basin wildrye seed prior to maximal physiological maturity. We hybridized basin wildrye and its close relative, creeping wildrye, which features the non-shattering sh6 allele. Eight generations of recombination and natural selection restored fertility to the interspecific hybrid, and intentional selection led to fixation of the sh6 allele, making L-74X homogeneous for the non-shattering trait. Averaged across two years, shattering genotypes averaged 19.4% greater seed yield per spike 23 days after pollination (DAP), but by 95 DAP non-shattering genotypes averaged 167% greater seed yield per spike. Germination averaged 72.1% and 86.4% at 23 DAP and 95 DAP, respectively, showing an increase with delayed seed harvest. The sh6 allele allows basin wildrye seed growers to delay seed harvest, concomitantly reducing shattering losses and improving physiological seed quality. This should moderate seed prices and improve seedling establishment in challenging semi-arid restoration environments.

Technical Abstract: Like many native grasses, basin wildrye (Leymus cinereus [Scribn. & Merr.] Á. Löve) is somewhat indeterminate and shatters its seed when ripe. To avoid shattering losses, growers tend to harvest basin wildrye seed prior to maximal physiological maturity. To resolve the intersecting problems of floral indeterminacy and seed shattering, USDA-ARS released the L-74X basin wildrye X creeping wildrye (L. triticoides [Buckl.] Pilger) germplasm (Reg. No. _________ , PI No. ________) on August 26, 2021. While L-74X has a narrow genetic base due to a biparental cross in its history, it can be used to introgress the non-shattering recessive sh6 allele of creeping wildrye (2n = 4x = 28) into 4x basin wildrye and closely related 4x Leymus species, hence a germplasm release is appropriate. L-74X originated with hybridization between 4x populations of basin wildrye and creeping wildrye. Eight generations of recombination and natural selection restored fertility to the interspecific hybrid, while intentional selection led to fixation of the sh6 allele. Averaged across two years, shattering genotypes (Sh6/sh6) averaged 19.4% greater (P < 0.05) seed yield per spike 23 days after pollination (DAP), but by 95 DAP non-shattering genotypes (sh6/sh6) averaged 167% greater (P < 0.05) seed yield per spike. Germination averaged 72.1% and 86.4% at 23 DAP and 95 DAP, respectively, showing an increase with delayed seed harvest. The sh6 allele allows basin wildrye seed growers to delay seed harvest, concomitantly reducing shattering losses and improving physiological seed quality. This should moderate seed prices and improve seedling establishment in challenging semi-arid restoration environments.