1a.Objectives (from AD-416):
The main objective of this project is to evaluate newly derived wheat breeding lines from U.S. wheat breeding programs in south Texas field plantings for resistance to natural infestations of various rust pathogens. Information will be provided to originating programs for use in selection of breeding lines for cultivar release and for development of new experimental lines.
1b.Approach (from AD-416):
80-100 entries from the USDA-ARS-coordinated SRPN and NRPN and 300-400 entries from the RGON will be planted at three locations in Texas, namely Bushland, Castroville, and McGregor. The material will be evaluated for resistance to natural infestations of leaf rust, stripe rust, and stem rust. Other observations will be recorded as appropriate. Information will be transferred to participating U.S. wheat breeding programs via USDA web-based reports. Great Plains wheat breeding programs will be invited to submit lines for evaluation in the Castroville nursery – this has averaged approximately 5,000 lines per year.
Wheat production throughout the entire Great Plains of North America can be adversely affected by wheat leaf, stem, or stripe rusts. Yearly infections, when present, commence in Texas and spores are carried north by the prevailing southerly winds. Selecting resistant materials in south Texas nurseries is a key component of the nation’s efforts to prevent wheat rust epidemics. In 2013, advanced breeding lines from all Great Plains wheat breeding programs were tested in a field trial at Castroville for responses to naturally occurring wheat rust pathogens. The primary sources of the tested materials were the USDA-ARS coordinated regional nursery trials, including the Southern (SRPN) and Northern (NRPN) Regional Nurseries and the Regional Germplasm Observation Nursery. These trials test advanced breeding lines approximately 2-3 years from cultivar release decisions. Approximately 40% of the 2013 SRPN entries and 25% of the NRPN entries were scored as either resistant, or moderately resistant, to natural infections of leaf rust in the south Texas trial. Leaf rust resistant materials also were found in all breeding programs entering lines in the 2013 Regional Germplasm Observation Nursery. This information will be used by breeding programs to select lines for cultivar release, and to identify resistant lines to use in new cycles of breeding to continue the process of introgressing rust resistant genes to the nation’s wheat germplasm base.