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Abstract

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 (LelAA7) are expressed in etiolated 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 LelAA 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 LelAA genes (LelAA5, 8, 10, and 11), with the greatest reduction associated with those genes with the strongest wild-type response to auxin. The remaining LelAA 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.

The Tomato (Solanum Lycopersicum cv. Micro-Tom) Natural Genetic Variation Rg1 and the DELLA Mutant Procera Control the Competence Necessary to Form Adventitious Roots and Shoots

“…8B), suggesting that this gene, which is the most highly expressed PIN gene in tomato (Pattison and Catalá, 2012), may be one of the components of the epistatic interaction seen in vitro and ex vitro between dgt and Rg1 (Figs 4–7). On the other hand, the low transcript accumulation of IAA11 in dgtRg1 when compared with Rg1 and MT indicated an epistatic effect of dgt , which presented a low transcript accumulation of this gene, as previously reported (Nebenfuhr et al, 2000). …”

Function of Cyclophilin1 as a long-distance signal molecule in the phloem of tomato plants

“…Sections of rootstock stem were incubated in an IAA solution with or without the addition of CsA. In agreement with earlier findings (Nebenführ et al , 2000; Spiegelman et al , 2015), auxin treatment caused a significant increase in the expression of both IAA10 and IAA11 in homografted VFN8 rootstock stems with minimal effect on expression of these genes in homografted dgt rootstocks (Fig. 7A, C).…”

“…Several physiological studies have established that while the dgt mutant is not impaired in IAA synthesis (Fujino et al , 1988) or uptake (Daniel et al , 1989; Muday et al , 1995), it is unresponsive to auxin (Kelly and Bradford, 1986) and exhibits a partial reduction in polar auxin transport (Ivanchenko et al , 2015). Corresponding to the auxin-insensitive phenotype, the dgt mutation is associated with a reduction in the levels of auxin-responsive transcripts, including small-auxin-up-regulated-RNA ( SAUR ) (Mito and Bennett, 1995), Aux/IAA , and ACC synthase (Nebenführ et al , 2000; Balbi and Lomax, 2003). Recent morphological studies have established that the absence of LRs in dgt mutants is due to an inability to form LR primordia from dividing pericycle cells (Ivanchenko et al , 2006).…”

Current challenges and future potential of tomato breeding using omics approaches

“…IAA9 is a negative auxin response regulator belonging to the Aux/IAA transcription factor gene family (Abel et al 1995, Nebenfuhr et al 2000). Integrated analysis of transcript and metabolite profiling of MicroTom tomato lines downregulated in the expression of the IAA9 gene was applied to investigate underlying molecular events during fruit set (Wang et al 2009).…”