Location: Sunflower and Plant Biology ResearchTitle: Genetic and phenotypic analyses indicate that resistance to flooding stress is uncoupled from performance in cultivated sunflower
|GAO, LEXUAN - UNIVERSITY OF BRITISH COLUMBIA|
|LEE, JOON SEON - UNIVERSITY OF BRITISH COLUMBIA|
|HUBNER, SARIEL - UNIVERSITY OF BRITISH COLUMBIA|
|QU, YAN - UNIVERSITY OF BRITISH COLUMBIA|
|RIESEBERG, LOREN - UNIVERSITY OF BRITISH COLUMBIA|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2019
Publication Date: 5/3/2019
Citation: Gao, L., Lee, J.S., Hubner, S., Hulke, B.S., Qu, Y., Rieseberg, L.H. 2019. Genetic and phenotypic analyses indicate that resistance to flooding stress is uncoupled from performance in cultivated sunflower. New Phytologist. 223((3):1657-1670. https://doi.org/10.1111/nph.15894.
Interpretive Summary: Field crops are often negatively affected by stresses caused by disease, insects, and weather. Among the important weather-related stresses for sunflower is flooding, which is relatively common in the early growing season in the northern plains of the USA. In our work, we developed a controlled flooding experiment in the greenhouse for young sunflower plants, and compared the results to a similar study in a field setting. The results indicated that there were four different types of plants, including one type that was high performing under both normal, control conditions and flooded conditions. In addition, an analysis technique called GWA showed which genes on the sunflower genome were associated with plant performance and flood resistance traits, and showed that most of the flood resistance genes were not tied to genes that resulted in poor plant performance. These results suggest that sunflower breeders should be able to increase flood resistance without much, if any, cost to plant performance in the field.
Technical Abstract: Given the rising risk of extreme weather caused by climate change, enhancement of abiotic stress-resistance in crops is increasingly urgent. But will the development of stress-resistant cultivars come at the cost of yield under ideal conditions? We hypothesize that this need not be inevitable, because resistance alleles with minimal pleiotropic costs may evade artificial selection and be retained in crop germplasm. Genome-wide association (GWA) analyses for variation in plant performance and flooding response were conducted in cultivated sunflower, a globally important oilseed. We observed broad variation in flooding responses among genotypes. Flooding resistance was not strongly correlated with performance in control conditions, suggesting no inherent trade-offs. Consistent with this finding, we identified a subset of loci conferring flooding resistance, but lacking antagonistic effects on growth. Genetic diversity loss at candidate genes underlying these loci was significantly less than for other resistance genes during cultivated sunflower evolution. Despite bottlenecks associated with domestication and improvement, low cost resistance alleles remain within the cultivated sunflower gene pool. Thus, development of cultivars that are both flooding tolerant and highly productive should be straightforward. Results further indicate that estimates of pleiotropic costs from GWA analyses explain, in part, patterns of diversity loss in crop genomes.