Figure 4.

Analysis of transgenic Arabidopsis tt4 mutants. A, Complementation of seed coat color and anthocyanin pigmentation. Seed coats of wild-type plants (Ler) are brown due to tannin deposition. Ler seedlings accumulate anthocyanin in cotyledons and hypocotyls when germinated on Murashige and Skoog medium without nitrogen sources (MS − N). Arabidopsis tt4 mutants produced seeds with yellow color and failed to accumulate anthocyanin under nitrogen deficiency. Note the complementation of tt4 phenotypes in T₁ lines of SbCHS2-expressing plants (tt4 + SbCHS2). On the other hand, SbCHS8 did not restore the tt4 mutations in T₁ transgenic plants (tt4 + SbCHS8). The same phenotypes were observed in the T₂ lines of SbCHS8-expressing plants (data not shown). B, HPLC profiles of transgenic tt4 plants. Acid-hydrolyzed extracts were prepared from T₁ lines and analyzed by HPLC with elution monitoring at A₃₆₀. Note the detection of peaks representing quercetin (Q, 19.0 min) and kaempferol (K, 23.0 min) in Ler and tt4 + SbCHS2 plants.