Fig. 2. Map-based cloning of TTR1 of Arabidopsis ecotype Est. (A) Schematic representations of the map-based cloning of TTR1. Contigs of three TAC clones and four fosmid clones were first identified and aligned near the DFR and nga129 markers. Subclones (n = 27) were generated from these fosmid clones, and each subclone was transformed into Col-0. Plants of each transgenic line were evaluated for the disease phenotype following TRSV inoculation. (B) Subclone 7-21, containing a single ORF of Est ecotype (TTR1) and a truncated transposable element, made the normally tolerant Col-0 sensitive to TRSV, whereas Col-0 transformed with the pPZP211 binary vector retained its tolerant phenotype. A single ORF TTR1 was reintroduced into the Col-0 background, and the LSN phenotype was confirmed in T₁ plants.