A szimbiotikus gümő kialakulásában résztvevő két gén azonosítása Medicago truncatula-ból térképezésen alapuló génizolálással. = Isolation of two Medicago truncatula genes involved in the development of the symbiotic nodule by map-based cloning.

A palyazat celja a Sinorhizobium meliloti es a Medicago truncatula kozott letrejovő szimbiotikus nitrogenkotő kapcsolat kialakitasaban resztvevő ket M. truncatula gen (DMI1 es PDL) azonositasa volt. A mutansok szimbiotikus fenotipusa azt valoszinűsitette, hogy a mutaciot szenvedett genek termekei a szimbiotikus gumő kialakulasanak korai szakaszaban, a bakterialis jelmolekula (Nod faktor) altal elinditott szignalutban, illetve a gumő organogenezisben vesznek reszt. A genek azonositasat terkepezesen alapulo genizolalassal vegeztuk el, az izolalt genek azonossagat pedig genetikai komplementacios kiserletekkel igazoltuk. Az DMI1 gen egy olyan feherjet kodol, amely nem mutat hasonlosagot semmilyen eddig ismert novenyi feherjevel, vagy annak alegysegevel. Tartalmaz viszont egy konzervativ doment, amely kisebb mertekű, de az egesz domenre kiterjedő hasonlosagot mutatott bakterialis kalium csatornak TrkA domenjevel, igy a DMI1 feherje feltetelezhetően kation csatornakent, vagy annak alegysegekent műkodik. A PDL gen klonozasa soran azonositottunk egy AP2-tipusu doment tartalmazo ERF tipusu transzkripcios faktort kodolo gent, amely tartalmazott egy mutaciot a pdl mutansban. Egyuttműkodő partnerunkkel bizonyitottuk a gen azonossagat es kimutattuk, hogy a gen szukseges a Nod faktor altal indukalt nodulin gen expressziohoz, es meghataroztuk a Nod factor szignalutban elfoglalt helyet. | The aim of this project was to identify two Medicago truncatula genes, DMI1 and PDL which are required to establish symbiotic nitrogen fixing interaction between Sinorhizobium meliloti and M. truncatula. Based on the mutant phenotype, DMI1 and PDL were proposed to act in the Nod factor signal transduction pathway and revealed that the DMI protein is essential to enable mycorrhizal associations. The DMI1 and PDL genes were identified in cooperation with other laboratories by map-based cloning; that is 'chromosomal walking' starting from the closely linked molecular markers to the mutant genes were carried out. Transformation experiments were performed using the wild type genes to complement the mutant phenotypes genetically. The DMI1 gene encodes a protein with low global similarity to a ligand-gated cation channel domain of archaea. The pdl mutant was allelic to the bit1 mutant that shows a slightly different mutant phenotype and the two genes were renamed as ERN (ERF Required for Nodulation). ERN encodes a protein containing a highly conserved AP2 DNA binding domain. We identified the position of ERN in the Nod factor signal transduction pathway and showed that ERN is necessary for Nod factor?induced gene expression.