Figure 2.

Cloning of the mutant tRNA^ala and recapitulation of auxin resistance. A, Mapping data. BAC, Bacterial artificial chromosome; cM, centimorgan, the unit of genetic distance describing the recombination frequency between two loci as 1%/cM. The observed G-to-A transition in the tRNA gene is highlighted. B, Unlike other tRNAs, which have multiple determinants located in the arms and core of the structure, the indicated (*) G3-U70 wobble conserved among tRNA^alas is the only major identity determinant (Hou and Schimmel, 1988; McClain and Foss, 1988). Therefore, we expect the documented phenotypes to occur only with this or other mutated tRNA^alas. C, Recapitulation. The top section is a picture of seedlings (right two, tRNA^ala mutant heterozygotes; center two, wild type; left two, recapitulation lines [text]) immediately after transfer to 0.5× MS vertical plates supplemented with 100 nm 2,4-D; the bottom section shows the same seedlings after 24 h continued growth. D, IAA19 induction. RT-PCR shows that IAA19 expression is induced by IAA (10 μm) in the mutant tRNA^ala lines. UBQ10 expression is not regulated by IAA and is included as a control.