The auxin-resistant diageotropica mutant of tomato responds to gravity via an auxin-mediated pathway

Rice, Margaret S.; Lomax, Terri L.

doi:10.1007/s004250050696

Cited by 30 publications

(29 citation statements)

References 26 publications

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“…demonstrates a pleiotropic phenotype that includes a slow gravitropic response, lack of lateral roots, reduced apical dominance, altered vascular development, and reduced fruit growth (Balbi and Lomax 2003;Coenen and Lomax 1998;Rice and Lomax 2000;Zobel 1973Zobel , 1974. While displaying reduced auxin sensitivity with respect to elongation growth and ethylene production (Kelly and Bradford 1986), the dgt mutant does not exhibit altered levels (Fujino et al 1988) or transport of auxin (Rice and Lomax 2000). Interestingly, the dgt mutation appears to affect the expression of only a subset of auxin-regulated genes in a tissue-and developmental stage-specific manner (Balbi and Lomax 2003;Mito and Bennett 1995;Nebenfuhr et al 2000).…”

Section: Introductionmentioning

confidence: 99%

The diageotropica gene of tomato encodes a cyclophilin: a novel player in auxin signaling

Ivanchenko

White

et al. 2006

Planta

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119

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The single gene, auxin-resistant diageotropica (dgt) mutant of tomato displays a pleiotropic auxin-related phenotype that includes a slow gravitropic response, lack of lateral roots, reduced apical dominance, altered vascular development, and reduced fruit growth. Some auxin responses are unaltered in dgt plants, however, and the levels, metabolism, and transport of auxin appear normal, indicating that the Dgt gene encodes a component of a specific auxin signaling pathway. By combining map-based cloning with comparative microsynteny, we determined that the Dgt gene encodes a cyclophilin (CYP) (LeCYP1; gi:170439) that has not previously been identified as a component of auxin signaling and plant development. Each of the three known dgt alleles contains a unique mutation in the coding sequence of LeCyp1. Alleles dgt(1-1)and dgt(1-2) contain single nucleotide point mutations that generate an amino acid change (G137R) and a stop codon (W128stop), respectively, while dgt(dp) has an amino acid change (W128CDelta129-133) preceding a 15 bp deletion. Complementation of dgt plants with the wild-type LeCyp1 gene restored the wild-type phenotype. Each dgt mutation reduced or nullified the peptidyl-prolyl isomerase activity of the GST-LeCYP1 fusion proteins in vitro. RT-PCR and immunoblot analyses indicated that the dgt mutations do not affect the expression of LeCyp1 mRNA, but the accumulation of LeCYP1 protein is greatly reduced for all three mutant alleles. The CYP inhibitor, cyclosporin A, partially mimics the effects of the dgt mutation in inhibiting auxin-induced adventitious root initiation in tomato hypocotyl sections and reducing the auxin-induced expression of the early auxin response genes, LeIAA10 and 11. These observations confirm that the PPIase activity of the tomato CYP, LeCYP1, encoded by the Dgt gene is important for specific aspects of auxin regulation of plant growth, development, and environmental responses.

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Section: Introductionmentioning

confidence: 99%

The diageotropica gene of tomato encodes a cyclophilin: a novel player in auxin signaling

Ivanchenko

White

et al. 2006

Planta

Self Cite

119

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“…Tomato dgt mutants exhibit a pleiotropic phenotype that includes a slow gravitropic response, lack of lateral roots, reduced apical dominance, shortened internodes, altered vascular development and reduced fertility and fruit growth (Zobel, 1973;Mito and Bennett, 1995;Rice and Lomax, 2000;Balbi and Lomax, 2003;Ivanchenko et al, 2006). Application of auxin to tomato dgt mutants does not stimulate shoot elongation and the effect on root growth inhibition is reduced compared with the wild type (WT).…”

Section: Introductionmentioning

confidence: 99%

The cyclophilin DIAGEOTROPICA has a conserved role in auxin signaling

et al. 2012

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SUMMARYAuxin has a fundamental role throughout the life cycle of land plants. Previous studies showed that the tomato cyclophilin DIAGEOTROPICA (DGT) promotes auxin response, but its specific role in auxin signaling remains unknown. We sequenced candidate genes in auxin-insensitive mutants of Physcomitrella patens and identified mutations in highly conserved regions of the moss ortholog of tomato DGT. As P. patens and tomato diverged from a common ancestor more than 500 million years ago, this result suggests a conserved and central role for DGT in auxin signaling in land plants. In this study we characterize the P. patens dgt (Ppdgt) mutants and show that their response to auxin is altered, affecting the chloronema-to-caulonema transition and the development of rhizoids. To gain an understanding of PpDGT function we tested its interactions with the TIR1/AFB-dependent auxin signaling pathway. We did not observe a clear effect of the Ppdgt mutation on the degradation of Aux/IAA proteins. However, the induction of several auxin-regulated genes was reduced. Genetic analysis revealed that dgt can suppress the phenotype conferred by overexpression of an AFB auxin receptor. Our results indicate that the DGT protein affects auxin-induced transcription and has a conserved function in auxin regulation in land plants.

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“…The dgt lesion is a single-gene mutation resulting in reduced sensitivity of dgt roots to auxin (Muday et al 1995, Rice andLomax 2000). The parental wild type of this mutant, VFN8, developed normal epidermal root cells when grown under control conditions (Table 2 and Fig.…”

Section: Electron Microscopymentioning

confidence: 94%

Acclimative changes in root epidermal cell fate in response to Fe and P deficiency: a specific role for auxin?

Schikora

Schmidt

2001

Protoplasma

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Root hair formation and the development of transfer cells in the rhizodermis was investigated in various existing auxin-related mutants of Arabidopsis thaliana and in the tomato mutant diageotropica. Wild-type Arabidopsis plants showed increased formation of root hairs when the seedlings were cultivated in Fe- or P-free medium. These extranumerary hairs were located in normal positions and in positions normally occupied by nonhair cells, e.g., over periclinal walls of underlying cortical cells. Defects in auxin transport or reduced auxin sensitivity inhibited the formation of root hairs in response to Fe deficiency completely but did only partly affect initiation and elongation of hairs in P-deficient roots. Application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid or the auxin analog 2,4-dichlorophenoxyacetic acid did not rescue the phenotype of the auxin-resistant axr2 mutant under control and Fe-deficient conditions, indicating that functional AXR2 product is required for translating the Fe deficiency signal into the formation of extra hairs. The development of extra hairs in axr2 roots under P-replete conditions was not affected by auxin antagonists, suggesting that this process is independent of auxin signaling. In roots of tomato, growth under Fe-deficient conditions induced the formation of transfer cells in the root epidermis. Transfer cell frequency was enhanced by application of 2,4-dichlorophenoxyacetic acid but was not inhibited by the auxin transport inhibitor N-1-naphthylphthalamic acid. In the diageotropica mutant, which displays reduced sensitivity to auxin, transfer cells appeared to develop in both Fe-sufficient and Fe-deficient roots. Similar to the wild type, no reduction in transfer cell frequency was observed after application of the above auxin transport inhibitor. These data suggest that auxin has no primary function in inducing transfer cell development; the formation of transfer cells, however, appears to be affected by the hormonal balance of the plants.

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The auxin-resistant diageotropica mutant of tomato responds to gravity via an auxin-mediated pathway

Cited by 30 publications

References 26 publications

The diageotropica gene of tomato encodes a cyclophilin: a novel player in auxin signaling

The diageotropica gene of tomato encodes a cyclophilin: a novel player in auxin signaling

The cyclophilin DIAGEOTROPICA has a conserved role in auxin signaling

Acclimative changes in root epidermal cell fate in response to Fe and P deficiency: a specific role for auxin?

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