Gene Flow in Centers of Diversity: The Case of Rice (Oryza Sativa L.) Dolores A. Ramirez, Ph. D. Dolores A. Ramirez, Ph. D. National Scientist, Philippines and University Professor Emeritus, University of the Philippines, Los Baños
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Definitions of gene flow 5
Consequences of gene flow: a marked change in allele or gene frequency Within a population or species: Introduce or re introduce genes into a population, hence increase genetic variation of that population. Across populations or species or genera : By moving genes around, it can make distant populations genetically similar to one another, hence reducing the chance of speciation. 6 The The less less gene gene flow flow between between two two populations, populations, the the more more likely likely that that the the two two populations populations will will evolve evolve into into two two new new species. species.
Types of gene flow 7
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) Two Centers of Diversity of Cultivated Rice : 1. West Africa for Oryza glaberrima. O. glaberrima remains locally important in some areas in Africa. Has a narrow range of genetic variation 2. Tropical and Sub Tropical Asia for Oryza sativa L. 8
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) 9
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) 10
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) Oryza nivara 11
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) There has been no major reproductive barrier between rice and its wild relatives, hence a continuous gene flow between them. A series of admixes have been observed. 12
Gene Flow in Centers of Origin / Diversity : The Case of Rice (Oryza sativa L.) 13
Sub Populations of Oryza sativa L. O.sativa originated from the Yantze valley, about 9,000 years ago. About 3,900 years ago, two sub populations developed, namely: 14
Sub Populations of Oryza sativa L. 15
Sub Populations of Oryza sativa L. (cont) Based on morphological and molecular characterization, five subpopulations are now recognized: 1. Indica 2. Aus / Boro 3. Tropical Japonica 4. Temperate Japonica 5. Aromatic (Basmati / Sadri) 16
The Gene Pool of Oryza sativa L. The rice gene pool includes about 22 wild relatives in the Genus Oryza and about 50 wild species in related genera of Tribe Oryzeae of the grass family Poaceae. 17
The Gene Pool of Oryza sativa L. Primary Gene Pool :Genome AA which include O. sativa Distribution : Asia O.rufipogon O. nivara 18
The Gene Pool of Oryza sativa L. Primary Gene Pool :Genome AA which include O. longistaminata O. barthii Distribution: Africa 19
The Gene Pool of Oryza sativa L. Primary Gene Pool :Genome AA which include O.glumaepatula Distribution: Latin America 20
The Gene Pool of Oryza sativa L. Primary Gene Pool :Genome AA which include O. meridionalis Distribution : Northern Australia and New Zealand 21
The Gene Pool of Oryza sativa L. Primary Gene Pool :Genome AA which include O.sativa L. f. spontanea weedy rice or red rice, a common weed in rice fields 22
The Gene Pool of Oryza sativa L. All taxa of the genome AA have relatively high sexual compatibility, high pollen and panicle fertility of the hybrids, indicating high survival of inter specific and intra specific hybrids; therefore high probability of gene flow within the genome AA. For Example: O. glumaepatula is the progeny of the cross between O. sativa and O. longistaminata 23
The Gene Pool of Oryza sativa L. 24
The Gene Pool of Oryza sativa L. 25
Gene Flow Studies 26
Gene Flow Studies 27
Gene Flow Studies 28
Gene Flow Studies 29
Gene Flow Studies 30
Gene Flow Mitigation 31
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