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Exploitation of sorghum’s natural diversity through genomic approaches holds promise for meeting global challenges in food and bioenergy production. Initially, we and others have characterized the levels of genetic diversity present within sorghum using both phenotypic and neutral molecular data, to understand how selection and demographic factors have affected and shaped diversity within populations, and to provide a foundation for making informed decisions regarding management and utilization of genetic resources. Currently, we are developing community resources and methodologies to efficiently dissect the genetics of important traits and identify functional allelic variation from the extensive germplasm resources that are available, facilitating sorghum improvement for food, feed and biomass uses.
Past projects (Publications)
- Basic population genetics of sorghum based on patterns of sequence variation (Hamblin et al 2004, 2005, 2006).
- Survey of SSR variation and testing for targets of selection associated with domestication (Casa et al 2005).
- Case study of a putative target of selection (Casa et al 2006).
- Linkage mapping of QTL for panicle architecture (Brown et al 2006).
Ongoing projects
- Development of diverse association mapping panel and RIL populations:
The sorghum genetics and breeding community has assembled a collection of 377 diverse lines, 236 of which are converted landraces (see “About Sorghum”), to be used in association mapping of complex traits. This population has been scored at 47 SSR loci and structure analysis has been done( Casa and Pressoir, in prep.)
- Identification of rapidly evolving genes:
A high substitution rate at a gene may be evidence of positive selection, frequently associated with sexual selection or host-pathogen interactions. A bioinformatics approach has been used to identify genes that show higher than average divergence to other grasses. Some of these genes appear to be involved in disease resistance (Zamora et al in prep).
- Genetic basis of carotenoid content:
Most sorghum varieties have white endosperm, which is low in carotenoid content. Increasing the carotenoid content through exploitation of yellow endosperm sorghums would improve its nutritional quality. Linkage and association methods are being used to study the genetic basis of variation in endosperm carotenoids.
- Genetic basis of fermentable carbohydrate content:
While most sorghum varieties have been selected for grain production, there is also interest in breeding sorghum as a biomass crop for ethanol production. Linkage and association methods are being used to study the genetic basis of variation in fermentable carbohydrate content.
- Association mapping of genes involved in panicle architecture:
Panicle architecture in sorghum is extremely diverse. Candidate gene from maize are being tested for their contribution to variation in sorghum panicle architecture.
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