Effect of Transgene and Wild Parents on Seed Dormancy of Crop-wild Rice Hybrids

Soil seed banks are used as gene pools of local plant species, and thus protecting local populations particularly those experiencing challenging environmental populations. Seed dormancy has significant implications in the dynamics of soil seed banks. S.S. Dong of Fudan University in China and a team of scientists estimated the seed dormancy of transgenic crop-wild hybrids to predict the persistence of transgenes in wild-plant soil seed banks.

Eight lines of wild rice Oryza rufipogon were crossed with three insect resistant transgenic lines. The resulting hybrids were selfed and backcrossed to get the population for testing. Seed germination was tested under three different conditions: normal, overwintering in soil, and heat shocking for one week. The effects of transgene, wild parent, and hybrid generation on hybrid seed germination were inspected.

Results showed that insect resistance transgenes (Bt and CpTI) had no effects on the seed dormancy of crop-wild hybrids, but significant wild parent effect was detected. Higher germination percentages and lower dormancy were observed in the seeds of the advanced generation hybrids than those of the earlier generations. Based on the findings, dormancy of hybrid seeds is affected by their genetic backgrounds. All hybrid seeds were found to have higher germination percentages and lower dormancy compared with the wild seeds. The scientists concluded that the hybrid seeds with the transgenes could persist in wild-plant soil seed banks.

Read the abstract at http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.2011.00504.x/abstract.