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Title: New Seed Dormancy Loci Detected from Weedy Rice-Derived Advanced Populations with Major QTL Alleles Removed from the Background

Author
item HENG, YE - South Dakota State University
item Foley, Michael
item GU, XING-YOU - South Dakota State University

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2010
Publication Date: 10/29/2010
Citation: Heng, Y., Foley, M.E., Gu, X. 2010. New seed dormancy loci detected from weedy rice-derived advanced populations with major QTL alleles removed from the background. Plant Science. 179:612-619.

Interpretive Summary: Seed dormancy is a key characteristic of weedy plants. We developed weedy rice as a model to identify genes (QTL) that regulate seed dormancy. Previously, we identified seven dormancy QTLs derived from a dormant line of weedy rice, which had been crossed and backcrossed to a nondormant breeding line of rice. In this research, we identified and confirmed three additional QTL using advanced populations. Additionally, we conclude that about 80% of the seed dormancy genes are eliminated during domestication and breeding activities.

Technical Abstract: Domestication of cereal crops from wild relatives tended to eliminate seed dormancy. Our objective was to identify all the detectable seed dormancy loci that differentiated between a weedy and a cultivated line of rice to understand the impact of domestication on distribution of dormancy genes. Three additional dormancy quantitative trait loci (QTL) were identified from two BC1F1 plant-derived F2 populations, in which the five previously known QTL-containing segments from the weedy rice donor were substituted by the genome of the recurrent parent. The three new QTL that accounted for 8-11% phenotypic variance in the F2s were confirmed with three BC1F2 plant-derived F3 populations. Counting the seven previously identified QTL, the parental lines differentiate at a total of 10 dormancy loci that vary in dominance from dominant, partially dominant, co-dominant, to recessive types. The weedy and cultivar parents contribute dormancy alleles to eight and two of the 10 loci, respectively. The two loci were newly detected. We concluded that a large proportion (8/10) of seed dormancy genes have been eliminated during domestication. The minor proportion (2/10) of dormancy genes retained in cultivars could be masked by those with a relatively large effect in a primary segregating population.