1a.Objectives (from AD-416):
To screen public spinach germplasm for new sources of resistance to downy mildew race 10.
1b.Approach (from AD-416):
The entire USDA spinach germplasm collection will be screened for downy mildew resistance in inoculated greenhouse tests. Documents Trust with California Leafy Greens Research Board. Log 37163.
This project contributes directly to the objective 3 of the parent project, genetic improvement of spinach. This report documents research conducted under a cooperative agreement with California Leafy Greens Research Program. Downy mildew (DM) caused by Peronospora farinose f. sp. Spinaciae is the most important disease for California spinach growers. Along with the rapid increase of spinach consumption and production in recent years, many new downy mildew races have emerged including the latest Races 10, 11, 12, and 13. We have conducted several increases of pathogen isolates and identified their races through differential host tests. Crosses were made among ten cultivars with different DM resistant genes to combine their resistances.
A recurrent selection method was used to increase the level of resistance to leafminers in nine populations of different leaf types. Plants with fewer leafminer stings or mines were selected and transplanted into isolators to produce seeds for further rounds of evaluation and selection. We screened spinach germplasm for resistances to Linuron herbicide, Verticillium wilt, Beet necrotic yellow vein virus, and leafspot diseases, as well as oxalic acid content. Genotypes with resistances to these diseases and low oxalate were identified. Resistant plants in the field were transplanted into isolators to produce seeds for future testing.