Diverged Copies of the Seed Regulatory Opaque-2 Gene by a Segmental Duplication in the Progenitor Genome of Rice, Sorghum, and Maize  

作　　者：Jian-Hong Xu Joachim Messing 

机构地区：[1]Waksman Institute of Microbiology, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854, USA

出　　处：《Molecular Plant》2008年第5期760-769,共10页分子植物（英文版）

摘　　要：Comparative analyses of the sequence of entire genomes have shown that gene duplications, chromosomal segmental duplications, or even whole genome duplications （WGD） have played prominent roles in the evolution of many eukaryotic species. Here, we used the ancient duplication of a well known transcription factor in maize, encoded by the Opaque-2 （O2） locus, to examine the general features of divergences of chromosomal segmental duplications in a lineagespecific manner. We took advantage of contiguous chromosomal sequence information in rice （Oryza sativa, Nipponbare）, sorghum （Sorghum bicolor, Btx623）, and maize （Zea rnays, B73） that were aligned by conserved gene order （synteny）. This analysis showed that the maize 02 locus is contained within a 1.25 million base-pair （Mb） segment on chromosome 7, which was duplicated ≈56 million years ago （mya） before the split of rice and maize 50 mya. The duplicated region on chromosome I is only half the size and contains the maize OHP gene, which does not restore the O2 mutation although it encodes a protein with the same DNA and protein binding properties in endosperm. The segmental duplication is not only found in rice, but also in sorghum, which split from maize 11.9 mya. A detailed analysis of the duplicated regions provided examples for complex rearrangements including deletions, duplications, conversions, inversions, and translocations. Furthermore, the rice and sorghum genomes appeared to be more stable than the maize genome, probably because maize underwent allotetraploidization and then diploidization.Comparative analyses of the sequence of entire genomes have shown that gene duplications, chromosomal segmental duplications, or even whole genome duplications （WGD） have played prominent roles in the evolution of many eukaryotic species. Here, we used the ancient duplication of a well known transcription factor in maize, encoded by the Opaque-2 （O2） locus, to examine the general features of divergences of chromosomal segmental duplications in a lineagespecific manner. We took advantage of contiguous chromosomal sequence information in rice （Oryza sativa, Nipponbare）, sorghum （Sorghum bicolor, Btx623）, and maize （Zea rnays, B73） that were aligned by conserved gene order （synteny）. This analysis showed that the maize 02 locus is contained within a 1.25 million base-pair （Mb） segment on chromosome 7, which was duplicated ≈56 million years ago （mya） before the split of rice and maize 50 mya. The duplicated region on chromosome I is only half the size and contains the maize OHP gene, which does not restore the O2 mutation although it encodes a protein with the same DNA and protein binding properties in endosperm. The segmental duplication is not only found in rice, but also in sorghum, which split from maize 11.9 mya. A detailed analysis of the duplicated regions provided examples for complex rearrangements including deletions, duplications, conversions, inversions, and translocations. Furthermore, the rice and sorghum genomes appeared to be more stable than the maize genome, probably because maize underwent allotetraploidization and then diploidization.

分 类 号：S339.2[农业科学—作物遗传育种] Q78[农业科学—农艺学]