A. Nebenführ, TJ White and T.L. Lomax (2000)
The diageotropica mutation alters auxin induction of a subset of the Aux/IAA gene family in tomato
Plant Molecular Biology 44, 73-84.
The diageotropica (dgt) mutation has been proposed to affect either auxin perception or responsiveness in tomato plants. It has previously been demonstrated that the expression of one member of the Aux/IAA family of auxin-regulated genes is reduced in dgt plants. Here, we report the cloning of ten new members of the tomato Aux/IAA family by PCR amplification based on conserved protein domains. All of the gene family members except one (LeIAA7) are expressed in etiol ated tomato seedlings, although they demonstrate tissue specificity (e.g. increased expression in hypocotyls vs. roots) within the seedling. The wild-type auxin-response characteristics of the expression of these tomato LeIAA genes are similar to those previously described for Aux/IAA family members in Arabidopsis. In dgt seedlings, auxin stimulation of gene expression was reduced in only a subset of LeIAA genes (LeIAA5, 8, 10, and 11), with the greatest reductio n associated with those genes with the strongest response to auxin. The remaining LeIAA genes tested exhibited essentially the same induction levels in response to the hormone in both dgt and wild-type hypocotyls. These results confirm that dgt plants can perceive auxin and suggest that a specific step in early auxin signal transduction is disrupted by the dgt mutation.
Gene Sequences:
The (partial) sequences of LeIAA1-11 can be downloaded from GenBank under the accession numbers AF022012 through AF022022. Simply follow this link and search the nucleotide data base with this search term: "AF022012[ACCN]:AF022022[ACCN]" (copy and paste without the quotation marks).