10-35 Fine Map Location of TTR1 in Arabidopsis thaliana that Confers Tolerance to Tobacco Ringspot Virus Infection. The virus accumulated to the same level and at the same rate in both the tolerant ecotype, Columbia, and the sensitive ecotype, Estland. Columbia does not develop symptoms while Estland turns chlorotic and dies following infection.
Genetic studies indicate that tolerance is incompletely dominant over sensitivity.
Infected heterozygotes are intermediate, displaying chlorosis and producing seeds at a reduced level. Because of the incomplete dominance, it is not clear whether tolerance or sensitivity is the active function. Initial mapping of the locus using more than F3 families indicated that the locus is located between markers DFR and nga129 with genetic distances of 5.7 cM and 6.3 cM, respectively. TTR1 was located to the interval between CIC2A12LE and yUP18A5LE, with genetic distances of 0.62 cM and 0.23 cM respectively. A YAC clone, CIC2A12, contains the TTR1 gene.