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An Arabidopsis flavonoid transporter is required for anther dehiscence and pollen development.

Thompson EP, Wilkins C, Demidchik V, Davies JM, Glover BJ - J. Exp. Bot. (2009)

Bottom Line: Mutant analysis demonstrates that the absence of FFT transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences.Root growth, seed development and germination, and pollen development, release and viability are all affected.Thus, as well as adding FFT to the incompletely described flavonoid transport network, it is found that correct reproductive development in Arabidopsis is perturbed when this particular transporter is missing.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK.

ABSTRACT
FLOWER FLAVONOID TRANSPORTER (FFT) encodes a multidrug and toxin efflux family transporter in Arabidopsis thaliana. FFT (AtDTX35) is highly transcribed in floral tissues, the transcript being localized to epidermal guard cells, including those of the anthers, stigma, siliques and nectaries. Mutant analysis demonstrates that the absence of FFT transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences. Root growth, seed development and germination, and pollen development, release and viability are all affected. Spectrometry of mutant versus wild-type flowers shows altered levels of a glycosylated flavonol whereas anthocyanin seems unlikely to be the substrate as previously speculated. Thus, as well as adding FFT to the incompletely described flavonoid transport network, it is found that correct reproductive development in Arabidopsis is perturbed when this particular transporter is missing.

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(a) Col0 versus fft-1 mean ratio of flavonoid (580 nm) and chlorophyll fluorescence (690 nm; Bolhar-Nordenkampf et al., 1989). Inset: example of the anther guard cell fluorescence scanned for analysis as viewed with the confocal microscope. (b) Examples of replicate fluorescence emission spectra from guard cells in Col0 and fft-1 anthers (background subtracted; normalized to 690 nm). (This figure is available in colour at JXB online.)
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fig6: (a) Col0 versus fft-1 mean ratio of flavonoid (580 nm) and chlorophyll fluorescence (690 nm; Bolhar-Nordenkampf et al., 1989). Inset: example of the anther guard cell fluorescence scanned for analysis as viewed with the confocal microscope. (b) Examples of replicate fluorescence emission spectra from guard cells in Col0 and fft-1 anthers (background subtracted; normalized to 690 nm). (This figure is available in colour at JXB online.)

Mentions: Following epifluorescent imaging of the WT and fft-1, it was hypothesized that confocal microscopy would reveal differences in flavonoid content of the plants. Confocal laser scanning microscopy was therefore used essentially to perform fluorescence spectroscopy, and thus indicate any changes to flavonoid levels (a technique previously used by Hideg et al., 2002, and discussed in Pfündel et al., 2006). Since GUS staining had occurred strongly in floral guard cells, inflorescence tissues treated with DPBA were excited with UV light (364 nm) and an emission spectrum was recorded (400–730 nm). Spectra were recorded from anther guard cells in WT or mutant flowers (inset, Fig. 6a) from the same position on an inflorescence (the first open flower below the unopened bud cluster), in which flavonoids should be comparable. A peak of emission from anther guard cells expected to result from flavonoid excitation could be visualized at 500–580 nm in WT tissues (Fig. 6b). Notably, a component of the fluorescence spectrum at ∼520 nm was absent in fft-1 (Fig. 6b), coinciding with the expected peak from flavonol–DPBA secondary fluorescence (Saslowsky and Winkel-Shirley, 2001). To quantify and test statistically the difference in replicate flowers, the well-defined flavonoid fluorescence peak at 580 nm and the peak from chlorophyll fluorescence were used to produce a ratio of flavonoid:chlorophyll emission. The ratios were significantly different between WT and fft-1, suggesting a lower flavonoid content in the mutant [WT, 1.60 (SE, 0.14) versus fft-1, 0.86 (SE, 0.05); t-test P=0.0016, 28 df; Fig. 6a]. Chlorophyll content was confirmed to be the same in WT and fft-1 mutant plants to make certain that levels of that pigment were not responsible for the differences observed, nor for any other aspect of the mutant phenotype (other photosynthetic parameters were also unaffected; see Supplementary Note S7 at JXB online). The products of the reactions of DPBA with flavonoids have not been comprehensively identified, however, so this can only be an indication of a difference in the flavonoid content in fft-1.


An Arabidopsis flavonoid transporter is required for anther dehiscence and pollen development.

Thompson EP, Wilkins C, Demidchik V, Davies JM, Glover BJ - J. Exp. Bot. (2009)

(a) Col0 versus fft-1 mean ratio of flavonoid (580 nm) and chlorophyll fluorescence (690 nm; Bolhar-Nordenkampf et al., 1989). Inset: example of the anther guard cell fluorescence scanned for analysis as viewed with the confocal microscope. (b) Examples of replicate fluorescence emission spectra from guard cells in Col0 and fft-1 anthers (background subtracted; normalized to 690 nm). (This figure is available in colour at JXB online.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2803208&req=5

fig6: (a) Col0 versus fft-1 mean ratio of flavonoid (580 nm) and chlorophyll fluorescence (690 nm; Bolhar-Nordenkampf et al., 1989). Inset: example of the anther guard cell fluorescence scanned for analysis as viewed with the confocal microscope. (b) Examples of replicate fluorescence emission spectra from guard cells in Col0 and fft-1 anthers (background subtracted; normalized to 690 nm). (This figure is available in colour at JXB online.)
Mentions: Following epifluorescent imaging of the WT and fft-1, it was hypothesized that confocal microscopy would reveal differences in flavonoid content of the plants. Confocal laser scanning microscopy was therefore used essentially to perform fluorescence spectroscopy, and thus indicate any changes to flavonoid levels (a technique previously used by Hideg et al., 2002, and discussed in Pfündel et al., 2006). Since GUS staining had occurred strongly in floral guard cells, inflorescence tissues treated with DPBA were excited with UV light (364 nm) and an emission spectrum was recorded (400–730 nm). Spectra were recorded from anther guard cells in WT or mutant flowers (inset, Fig. 6a) from the same position on an inflorescence (the first open flower below the unopened bud cluster), in which flavonoids should be comparable. A peak of emission from anther guard cells expected to result from flavonoid excitation could be visualized at 500–580 nm in WT tissues (Fig. 6b). Notably, a component of the fluorescence spectrum at ∼520 nm was absent in fft-1 (Fig. 6b), coinciding with the expected peak from flavonol–DPBA secondary fluorescence (Saslowsky and Winkel-Shirley, 2001). To quantify and test statistically the difference in replicate flowers, the well-defined flavonoid fluorescence peak at 580 nm and the peak from chlorophyll fluorescence were used to produce a ratio of flavonoid:chlorophyll emission. The ratios were significantly different between WT and fft-1, suggesting a lower flavonoid content in the mutant [WT, 1.60 (SE, 0.14) versus fft-1, 0.86 (SE, 0.05); t-test P=0.0016, 28 df; Fig. 6a]. Chlorophyll content was confirmed to be the same in WT and fft-1 mutant plants to make certain that levels of that pigment were not responsible for the differences observed, nor for any other aspect of the mutant phenotype (other photosynthetic parameters were also unaffected; see Supplementary Note S7 at JXB online). The products of the reactions of DPBA with flavonoids have not been comprehensively identified, however, so this can only be an indication of a difference in the flavonoid content in fft-1.

Bottom Line: Mutant analysis demonstrates that the absence of FFT transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences.Root growth, seed development and germination, and pollen development, release and viability are all affected.Thus, as well as adding FFT to the incompletely described flavonoid transport network, it is found that correct reproductive development in Arabidopsis is perturbed when this particular transporter is missing.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK.

ABSTRACT
FLOWER FLAVONOID TRANSPORTER (FFT) encodes a multidrug and toxin efflux family transporter in Arabidopsis thaliana. FFT (AtDTX35) is highly transcribed in floral tissues, the transcript being localized to epidermal guard cells, including those of the anthers, stigma, siliques and nectaries. Mutant analysis demonstrates that the absence of FFT transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences. Root growth, seed development and germination, and pollen development, release and viability are all affected. Spectrometry of mutant versus wild-type flowers shows altered levels of a glycosylated flavonol whereas anthocyanin seems unlikely to be the substrate as previously speculated. Thus, as well as adding FFT to the incompletely described flavonoid transport network, it is found that correct reproductive development in Arabidopsis is perturbed when this particular transporter is missing.

Show MeSH
Related in: MedlinePlus