Fitness estimation through performance comparison of F1 hybrids with their parental species Oryza rufipogon and O. sativa.
OBJECTIVE
Introgression of crop genes into populations of wild relatives has important implications for germplasm conservation as well as for the persistence of novel transgenes in wild populations. Studies of hybrid fitness can be used to evaluate the potential for introgression to occur following episodes of interspecific hybridization.


METHODS
This study estimated relative fitness of interspecific hybrids through performance comparison of F(1) hybrids with their parental species, a cultivated rice (Oryza sativa) Minghui-63 and perennial common wild rice (O. rufipogon) under the cultivation conditions.


RESULTS
Compared with their parents, the hybrids had the lowest values of seedling survival ability, pollen viability and seed production; intermediate values of seed germination, spikelet production and flag leaf areas; and the highest values of plant height, number of tillers and panicles. The hybrids performed poorly at the stage of sexual reproduction, although they had a slightly higher hybrid vigour at the vegetative growth stage and better tillering ability than their wild parent. There were no significant differences in composite fitness across the whole life-history between the hybrids and their wild parental species.


CONCLUSIONS
Rice genes, including transgenes, might persist in wild rice populations through vegetative and sexual reproduction. Further studies are needed to examine whether the extent of gene flow from rice is sufficiently significant to influence genetic diversity in wild populations of O. rufipogon, a species that has become endangered in some regions of south-east Asia.
Song
Zhi Ping
ZP
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Fudan University, Shanghai 200433, China.
Lu
Bao-Rong
BR
Wang
Bin
B
Chen
Jia Kuan
JK
D002470:Cell Survival / Q000235:genetics; D005816:Genetic Complementation Test / Q000379:methods; D006823:Hybrid Vigor / Q000235:genetics*; D006824:Hybridization, Genetic / Q000235:genetics*; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D011058:Pollen / Q000235:genetics / Q000254:growth & development; D012098:Reproduction / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000254:growth & development