326회 Presence of Phytopathogenic Fungal Microsatellite DNA in Plant Ge…

326회

연사 : 김 남 수 , 강원대학교 농업생명과학대학 식물응용과학부

제목:  Presence of Phytopathogenic Fungal Microsatellite DNA in Plant Genomes and Its Possible Role in Plant Chromosome Organization

Abstract

Although the biological function of satellite DNAs is still very elusive, the classical view of them as "junk DNA" or "selfish DNA" is being changed by several lines of evidence. This seminar will show the presence of phytopathogenic fungal microsatellite sequences in plant genomes as one example of a biological function of the satellite DNAs. We isolated a piece of TC microsatellite DNA from rice blast fungus for the purpose of race identification of the blast fungi. There were 30 bp direct repeat sequences in the flanking regions of the TC microsatellite repeat. This DNA is very abundant in the blast fungal genome. Interestingly, we also isolated DNA fragments, which share almost identical DNA sequences with the blast fungal microsatellite DNA, from several Graminae plant species. These plant TC microsatellites are also present in very high copy number in the corresponding plant genomes. Because several cases were known about horizontal DNA transfer  in other systems, horizontal movement of this satellite DNA between pathogenic fungi and plant species is cautiously proposed. Another interesting phenomenon is the chromosomal organization of this satellite DNA in plant species. We have examined chromosomes of more than 20 plant species with the above fungal satellite DNA as a probe by FISH analysis. Among them, all B genome diploid wheats, Hordeum vulgare, and H. murinum have this DNA in clustered locations in their chromosomes. Hordeum vulgare, cultivated barley, showed FISH signals on all centromeres, but this was not found in others. We know that the centromere is very important for proper chromosome movement during cell division. Why has this satellite DNA been built up only in H. vulgare centromeres, but not in others ? A study of the hybrid between H. vulgare and H. bulbosum will be described using the fungal microsatellite DNA as a probe to differentiate chromosomes and chromosome movement during cell division.