Ozet. Arabidopsis thaliana (Arabidopsis)’nin kromozom sayisinin az olmasi, bu bitkinin genetik yapisinin diger bitki turlerine gore daha kolay calisilmasina olanak saglamakta, ayrica diger bitkilerde patojenlere karsi gozlenen ana savunma mekanizmalari bu bitkide de bulunmaktadir. Bu acidan, konukcu bitkilerin patojen saldirilarina karsi savunma mekanizmalarini calisma konusunda Arabidopsis bitkisi ideal bir model sistem olusturmaktadir. Bu derlemenin amaci, patojenlere karsi bitki savunma mekanizmasinin genetigini anlamada Arabidopsis’in bir sablon olarak nasil kullanildigini, bitki ekotiplerinin patojen izolatlarina karsi gosterdigi farkliliklari (duyarlilik ve dayaniklilik) ortaya koyacak inceleme metodlarini aciklamaktadir. Anahtar Kelimeler: Arabidopsis thaliana, Peronospora parasitica, hastaliklara dayaniklilik, mutant bitkiler A Model Plant In Host-Pathogen Interaction: Arabidopsis thaliana Abstract. Because of its small genome, genetic studies are performed easier in Arabidopsis thaliana (Arabidopsis) compared to other plants and it exhibits all of the major kinds of defense responses described in other plants. Thus, Arabidopsis provides to be an ideal model system for studies of host defense responses to pathogen attack. This review details methods to isolate and utilize phytopathogens useful as probes in understanding the genetics of plant defense responses in Arabidopsis. As well, it will be defined how screening systems can be set up to detirmine differential responses (resistance and susceptibility) of Arabidopsis ecotypes to pathogen isolates. Key Words: Arabidopsis thaliana, Peronospora parasitica, disease resistance, mutant plants