Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/1995
Publication Date: N/A
Interpretive Summary: Stripe rust of wheat is especially destructive in the western United States. The disease is controlled mainly by resistant cultivars, especially seedling resistance and high-temperature, adult-plant (HTAP) resistance. Seedling resistance is expressed at all stages of plant growth and is race-specific. Varieties with seedling resistance often become susceptible within a few years after their use, because of the evolution o new virulent races of the rust pathogen. HTAP resistance increases as plants become older at higher temperatures but not at lower temperatures. HTAP resistance is non-race-specific and durable. The winter wheat varieties Stephens and Druchamp have both types of resistance. To study the gene action of HTAP resistance and its interaction with seedling resistance, Stephens and Druchamp were crossed with each other and with Michigan Amber (a susceptible variety) and Paha (a seedling-resistant club wheat). Based on quantitative genetic analyses, expression of dominance for HTAP resistance in Stephens and Druchamp was determined. The additive effect of the genes was most important. Dominance was higher when HTAP resistance was combined with the seedling resistance. The gene interactions contributed significantly to HTAP resistance in Druchamp but not in Stephens. The results also suggested that HTAP resistance is influenced by which variety is the female parent. Information is provided on how HTAP resistance is inherited and how HTAP and seedling resistance can be used in improving resistance to stripe rust.
Technical Abstract: Stephens and Druchamp have both race-specific seedling resistance and non race specific high-temperature, adult-plant (HTAP) resistance to Puccinia striiformis. Reciprocal, diallel crosses were made between Stephens and Druchamp and of Stephens and Druchamp with Paha (a seedling-resistant club wheat) or Michigan Amber (a susceptible wheat). Parents and F1, F2, and backcross progeny were evaluated for resistance in the fields using stripe rust intensity (severity) data transformed to area under disease progress curve (AUDPC). Generation means and variances were used to study gene action and cytoplasmic effects. The results show that HTAP resistances in Stephens and Druchamp are either partially recessive or partially dominant. Based on the joint scaling tests, the additive component for HTAP resistance was significant for both Stephens and Druchamp. When HTAP resistance was effective and seedling resistance was ineffective in the same parent, the dominant component and additive X additive, additive X dominant, and dominant X dominant epistatic interactions contributed significantly to HTAP resistance in Druchamp but not in Stephens. When HTAP and seedling resistances were effective in the same parent, the dominant component and additiveX additive and dominant X dominant interactions were significant in both Stephens and Druchamp and the additive X dominant interaction was significant in Stephens but not in Druchamp. When HTAP resistance was effective in one parent and seedling resistance was effective in the other parent, the dominant component and the additive X additive and dominant X dominant interactions were significant in the Druchamp crosses but not in the Stephens Crosses.