Improving Breeding Efficiency of Locally Adapted Cereal Rye Varieties

Improving breeding efficiency of locally-adapted cereal rye varieties Breeding for regionally adapted cereal rye (Secale cereale) varieties can contribute to increased profits and improved sustainability in Kentucky. This proposal will support ongoing breeding of University of Kentucky (UK) open-pollinated varieties (OPVs) through improving efficiency throughout the breeding cycle, from refining advanced breeding lines (late stage), to developing new stocks and tools (early stage). This proposal addresses the KYSGGA goals of reducing winter fallow and developing new small grain varieties. Our objectives are: Obj 1. Breeding for increased seed size and improved agronomic performance. We will select the largest seeded plants within current UK rye populations developed by Dr. Phillips (work funded by KySGGA). By selecting within populations, in addition to among populations, we will increase selection intensity, ideally leading to larger seeded varieties that are preferred by distillers. We will use screens to select for larger seed size after harvest this summer, plant those seeds in Fall 2023, and the evaluate resulting seed size and agronomic traits in Summer 2024. Obj 2. Developing new stocks and tools to breed dwarfing varieties. Tall ryes lead to inconsistent yields and difficulty planting soybeans following rye. We will thus work to breed shorter OPVs by introgression of dwarfing genes. Through literature and record reviews, we will ascertain which dwarfing genes are present in UK rye, other non-proprietary sources of dwarfing genes, and available molecular markers. We will then synthesize this information and germplasm to develop ‘dwarfing gene donor populations’. Germplasm acquisition and marker testing will be done in Fall 2023, and the plants will be cross-pollinated to create the first selection cycle of the dwarf population(s) in Summer 2024. After creating dwarfing populations and a suite of molecular markers this year, they will be used in breeding in following years. Markers and dwarf populations will increase efficiency in deploying dwarfing genes in regionally adapted varieties. Obj 3. Testing approaches for isolation by detecting pollen contamination. The need for isolation distances to maintain rye breeding stocks limits the amount of germplasm that can be screened. We propose testing efficacy of different isolation methods using coleoptile color as an indicator of pollen contamination. Rye coleoptiles are purple (red) or green, where purple is dominant to green. Thus, rye with green coleoptiles can be used as indicators of pollen contamination from rye with purple coleoptiles. Importantly, visual screening can be done shortly after germination. We will identify varieties with uniformly green or purple coleoptiles, and then plant green coleoptile indicators surrounded by purple with different barriers or field configurations. Seeds from the green indicators will be harvest and germinated in Summer 2024 to assess efficacy.