Fruit-Surface Flavonoid Accumulation in Tomato Is Controlled by a SlMYB12-Regulated Transcriptional Network
Figure 9
The transgenic amiR-SlMYB12 lines exhibit a y-like phenotype.
(A) Red box indicates the location of the amiR-SlMYB12 target sequence on the SlMYB12 gene, arrows indicate the position of RT–PCR primers, and the sequence alignment on the right demonstrates the specificity of this artificial microRNA. (B) Expression of the amiR-SlMYB12 precursor in samples extracted from leaves of 35S:amiR-SlMYB12-transgenic lines and non-transgenic controls. (C) Fruit of 35S:amiR-SlMYB12-transgenic lines display colorless peel. (D) RT–PCR relative expression analysis of phenylpropanoid/flavonoid-related regulators and structural genes in fruit peel of wt and 35S:amiR-SlMYB12-transgenic lines. Indicated by asterisks are significantly reduced levels analyzed by Student's t-test (n = 3; P<0.05; bars indicate standard errors). (E) PCA of metabolic profiles obtained by UPLC-QTOF-MS analysis carried out on peel samples of wt cv. AC and cv. MT, y mutant and an amiR-SlMYB12-transgenic line at the red stage of fruit development. Analysis was performed with the TMEV program using normalized and log-transformed data. (F) Total ion chromatograms (TICs) of wt (cv. MT) and 35S:amiR-SlMYB12 peels at the red stage of fruit development, acquired in the negative mode using UPLC-QTOF-MS (in relative intensity, 100% corresponds to 6.14×104 counts). The putative identity of the differential compounds is: 1 - quercetin-dihexose-deoxyhexose, 2 - quercetin-hexose-deoxyhexose-pentose, 3 - quercetin-rutinoside (rutin), 4 - phloretin-di-C-hexose, 5 - kaempferol-glucose-rhamnose, 6 - naringenin chalcone, 7 - dicaffeoylquinic acid III, 8 - tricaffeoylquinic acid. Red and blue numbers indicate metabolites that showed elevated or reduced levels in the transgene samples in comparison to those of their corresponding wt, respectively. (G) Relative levels of NarCh in cv. MT and 35S:amiR-SlMYB12, expressed as chromatographic peak areas, calculated for m/z 271.06 Da (n = 5).