Dormancy Genes From Weedy Rice Respond Divergently to Seed Development Environments

Abstract

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 QTL in a synchronized nondormant genetic background. Two genetically identical populations segregating for qSD1, qSD7-1, and qSD12 were grown under 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 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 3 E interactions, which in magnitude were greater than environmental main effect. The divergent responses of dormancy genes observed in this simple multigenic system presumably 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.

Morphological Characterization of Weedy Rice Populations from Different Regions of Asia

“…Biological characteristics can clarify typical weedy rice types and provide a theoretical basis for its prevention and control. Moreover, related species materials for gene flow studies in the environmental safety assessment of genetically modified rice, and valuable resistance genes should be explored as breeding materials (Lu and Snow, 2005;Gu et al, 2006;Rong et al, 2007). (Table 6).…”

Induction of Dormancy in Arabidopsis Summer Annuals Requires Parallel Regulation of DOG1 and Hormone Metabolism by Low Temperature and CBF Transcription Factors

“…Previous work has shown that lowering seed maturation temperatures induces high levels of dormancy in rapid cycling Arabidopsis ecotypes (Schmuths et al, 2006;Donohue et al, 2008;Chiang et al, 2009) as well as other species (Fenner, 1991;Gu et al, 2006). We confirmed that this was indeed a dormancy phenomenon by stimulating high levels of germination in seeds matured at low temperatures by applying multiple dormancy breaking treatments or by removing coat-imposed dormancy by nicking the seed coat (see Supplemental Figure 1A online) and by showing that embryo and seed coat morphology was normal in seeds developed at 108C (see Supplemental Figures 1B and 1C online).…”

Was Asian Rice (Oryza sativa) Domesticated More Than Once?

“…Secondary dormancy remains an important characteristic in indica varieties, where seeds retain viability during hot, humid conditions between planting seasons. The most detailed studies of dormancy have been conducted with an accession of wild-like weedy rice from Thailand (accession SS18-2) that exhibits hull-imposed dormancy [21][22][23][24][25][26]. The most important dormancy-related QTL in this Thai accession was located on chromosome 12, explaining about 50% of the phenotypic variance [22,24].…”