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Tapping the potential of USDA's sorghum germplasm collection

A wealth of genetic diversity and valuable traits exists in sorghum germplasm collections, particularly those from the species’ center of origin in present day Sudan and Ethiopia.

Sorghum plantsHowever, sorghum is a short-day plant, and much of the USDA’s sorghum germplasm collection flowers too late or is too tall to be exploited for seed production in temperate zone environments.

Building upon the success of the historical TAES-USDA Sorghum Conversion Program, a team of public and private sector scientists launched a renewed effort to “convert” accessions from the USDA’s Sudanese and Ethiopian collections into plants adapted to temperate zones.

This was accomplished by introgressing day-neutral flowering alleles and dwarf-height genes into exotic backgrounds, the team reports in the January 2016 issue of the Journal of Plant Registrations.  

In their approach, the scientists augmented conventional backcrossing with genomic-assisted selection; that is, they used genotyping by sequencing to reduce the number of backcross generations needed to recover the tropical genome in an adapted genetic background.

The greatest hindrance to recovering the exotic genome in a short, early-flowering genotype was linkage drag flanking the introgressed flowering and dwarfing recessive alleles; this was reduced, but not eliminated, by genomic-assisted selection.

The resulting registered material contains germplasm with highly desirable breeding values. it also includes new sources of B lines that may help expand the narrow genetic base observed in female parents of hybrid sorghum breeding programs.

This article originally appeared in the February 2016 issue of CSA News magazine.