Jump to Main Content
No effect of transgene and strong wild parent effects on seed dormancy in cropâwild hybrids of rice: implications for transgene persistence in wild populations
- Dong, S.S., Xiao, M.Q., Rong, J., Liao, H., Lu, B.âR., Chen, J.K., Song, Z.P.
- Annals of applied biology 2011 v.159 no.3 pp. 348-357
- Bacillus thuringiensis, Oryza rufipogon, buried seeds, environmental factors, gene pool, genetic background, hybrids, overwintering, seed dormancy, seed germination, soil, transgenes, wild rice
- Soil seed banks act as a gene pool for local plant species and, as such, can buffer local populations, especially those experiencing challenging environmental conditions. Seed dormancy has important implications to dynamics of soil seed banks. Therefore, estimating the seed dormancy of transgenic cropâwild hybrids could shed light on the persistence of transgenes in wildâplant soil seed banks. Individuals from eight populations of wild rice Oryza rufipogon were crossed with those of three insectâresistant transgenic rice lines. Selfed (F2âF4) and backcrossed populations (BC1, BC1F2 and BC1F3) were then made from the hybrids. Seed germination was tested under three treatments: (a) normal; (b) overwintering in soil; and (c) oneâweek heatâshocking. The effects of transgene, wild parent and hybrid generation on hybrid seed germination were examined. No significant effect of insectâresistant transgenes (Bt and CpTI) was detected on the seed dormancy of cropâwild hybrids, while a significant wild parent effect was found. The seeds of advanced generation hybrids have higher germination percentages and lower dormancy than do those of F1 and BC1 generations. The study showed that the dormancy of hybrid seeds was determined mainly by their genetic backgrounds. All hybrid seeds have higher germination percentages and lower dormancy (and, consequently, a poorer overwintering ability), compared with wild seeds, and reduce dormancy would contribute to a fitness disadvantage, compared with wild types. Therefore, such seeds might form part of naturally occurring soil seed banks, through which crop genes would persist in wild populations.