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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Research Project #436510

Research Project: Rapid Generation Advance through Doubled Haploids and Speed Breeding in Wheat

Location: Wheat Health, Genetics, and Quality Research

Project Number: 2090-21000-033-17-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 28, 2019
End Date: Aug 28, 2022

Objective:
Objective 1. Genetically improve soft white winter and club wheat for environmental resilience, disease resistance, and end-use quality. Subobjective 1A: Develop and release club (Triticum aestivum ssp. compactum) wheat cultivars with resistance to major regional diseases and adaptation to diverse environments in the western U.S. Objective 2. Identify genetic resources and introgress multiple genes for resistance to stripe rust and to soil borne diseases into wheat germplasm. Subobjective 2B: Introgress novel sources of resistance to stripe rust and soil borne disease from landraces into adapted wheat germplasm. Subobjective 2C: Conduct collaborative pre-breeding to introgress disease resistance from multiple germplasm accessions into adapted germplasm.

Approach:
Doubled haploids of wheat will be developed using the Maize hybridization technique. The ARS will supply the cooperator with F1 or BC1 seeds from crosses among wheat germplasm. Briefly, the ARS will emasculate the wheat flower prior to anthesis and pollinate with fresh maize pollen. The cooperator will spray the developing embryo with a dilute growth regulator and bagged to prevent contamination. Fourteen to sixteen days after pollination, the cooperator will excise embryos excised under sterile conditions and place them on MS media until they form roots and germinate. The cooperator will treat young plantlets with colchicine to cause the chromosome numbers to double. The cooperator will vernalize the putative doubled haploids. ARS will then grow them in the WSU plant growth facility. Seed that develops on fertile tillers is a doubled haploid and is returned to the breeding program. For speed breeding, the ARS will develop segregating populations. The cooperator will advance them to the F2 or BC1-F1 generation as follows: The population is germinated in germination boxes and vernalized for 6 weeks at 4oC under a 16-hour daylength. After vernalization, the germination paper is split and the paper with the adhering seedlings is planted into one-gallon pots in potting soil and placed into the greenhouse at 25oC and a 16-hour daylength. The crowding the pots ensures that only a single small head is produced from each plant. The plants are dried down as soon as kernels develop, harvested at physiological maturity and dried. The cycle is repeated for one or two more generations. The ARS and the cooperator will continue to evaluate some environmental parameters such as the quality of the light, the duration of the light, the optimal temperature for plant growth and the use of various plant growth regulators to speed time to flowering to see which are best to use for speed breeding.