Összehasonlító géntérképezés és szekvenciaszintű összehasonlítás pillangósok és egyéb kétszikűek genomja között = Comparative mapping and sequence analysis of the genomes of legumes and other dicotyledonous plants

A diploid lucerna terkepezese soran azonositottunk egy egyedet, melyben az RPS13 (ribosomal protein S13) genhez homolog lokusz deleciot szenvedett, de nem volt fenotipikus valtozas. Megallapitottuk, hogy a delecio az RPS13 gen egy csonka valtozatat erintette, ezert arra kovetkeztettunk, hogy ez a genkopia egy mRNS molekulan keresztul retrotranszpozicioval epult vissza a genomba, es a gen nem funkcional. Egy M. truncatula levelfejlődesi mutans mutaciojanak allapitottuk meg terkepezesen alapulo genizolalas segitsegevel előszor a terkephelyet a kettes kapcsoltsagi csoporton, majd a fenotipusert felelős mutaciot (egy G->A nukleotid csere, amely glutaminsav->lizin aminosav cserehez vezet). Az erintett genről kiderult, hogy az Arabidopsis thaliana Immutans gennel nagyfoku homologiat mutato, ezert a M. truncatula Immutans homologjanak tekintjuk. Az Immutans gen egy plasztokinon oxigen: oxidoreduktazt kodol, melynek szerepe van a karotenoid bioszintetikus utvonalban es terminalis oxidazkent funkcional a plasztiszokban. Szekvencia homologiak es analizis alapjan elmondhatjuk, hogy a kimutatott aminosavcsere a mutans novenyekben az enzim vasion koteseben resztvevő egyik aminosavat erintette, ami a mutans fenotipushoz vezethetett. Kozel 100 gen osszehasonlito terkepezeseből megallapithattuk, hogy a Medicago truncatula es a borso genomjai nagy mertekben kolinearisak, s az elteresek, mint a kulonboző kromoszomaszam is, par nagyobb genomialis atrendezessel megmagyarazhato. | We have identified a mutant individual during the genetic mapping of the diploid alfalfa, in which a deletion could be demonstrated in one of the locus having sequence homology to the RPS13 gene. This deletion however had no phenotypic effect. It was demonstrated that this allele contained a truncated copy of the RPS13 gene. This truncated gene was absent in the deletion derivative. This copy was the consequence of the reinsertion of a DNA copy of RPS13 mRNA through retrotransposition, consequently, this was not a functional copy. We have identified the map position as well as the nature of the mutation by map based cloning of a mutant gene which originated from a Medicago truncatula mutant displaying leaf variegated phenotype. The mutation was G-A nukleotid transition leading to a glutamate-lysine amino acid changes. The effected gene was homologous to the Arabidopsis thaliana Immutans gene, therefore the gene was considered as the M. truncatula Immutans ortholog. The immutans gene is encoding a plastochinon oxigen:oxidoreductase, which is involved in the carotenoide biosynthesis. From the result it can be concluded that the amino acid change identified was the consequence of the variegated phenotype of the M. truncatula mutant. Almost 100 genes have been mapped in both alfalfa and pea. Comparative mapping revealed that the two genomes are highly syntenic, and that the differences, like the different chromosome numbers too, are the consequences of few large genomic rearrangements.