Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 18, 2005
Publication Date: February 1, 2006
Citation: Gu, X.-Y., Kianian, S. F., Foley, M.E. 2006. Dormancy genes from weedy rice respond divergently to seed development environments. Genetics. 172(2):1199-1211.
Interpretive Summary: Seed dormancy is a key characteristic of weedy plants. In the course of our research to develop weedy rice as a system to map-base clone dormancy quantitative trait loci (QTL), we used marker assisted selection and backcrossing techniques to isolate the QTLs qSD1, qSD7-1, and qSD12 into individual populations to estimate genetic parameters for individual QTLs in a synchronized genetic background under two environmental conditions. Significant genotype by environmental interactions were detected with low temperature tending to enhance dormancy in both environments. This response to temperature is consistent with that found for other cereal grain species.
Genes interacting with seed developmental environments control primary dormancy. To understand how a multigenic system evolved to adapt to the changing environments in weedy rice, we evaluated genetic components of three dormancy QTLs in a synchronized non-dormant genetic background. Two identical populations segregating for qSD1, qSD7-1, and qSD12 were grown in greenhouse and natural conditions differing in temperature, relative humidity, and light intensity during seed development. Low temperatures tended to enhance dormancy in both conditions. However, genotypes responded to the environments divergently so that two populations displayed similar distributions for germination. Additive and/or dominance effects of the three loci explained about 90% of genetic variances and their epistases accounted for the remainder in each environment. The qSD1 and qSD7-1 main effects were increased, while the qSD12 additive effect was decreased by relatively low temperatures. Both gene main and epistatic effects were involved in G-by-E interactions, which in magnitude were greater than environmental main effect. The divergent responses of dormancy genes observed in this simple multigenic system have selective advantages in natural populations adapted to changing environments and hence represent a genetic mechanism stabilizing the dormancy level of weedy rice ripened in different seasons or temperature regimes.