Fig. 6

Genes associated with flavonoid biosynthesis in sea buckthorn. a Identification of structural flavonoid biosynthesis genes in H. tibetana. b Expression level of genes involved in the flavonoid biosynthesis pathway was detected in four different tissues of H. tibetana. The red colors indicated high expression levels. The blue colors indicated low expression levels. c the total flavonoid content of four different tissues of H. tibetana. d Maximum-likelihood trees of C4H family genes that were constructed using the amino acid sequences with 1000 bootstrap repeats. e Induction process of sea buckthorn hairy roots. CK, empty vector; OE-HtC4H1, overexpression lines (K599-1302-HtC4H1); OE-HtC4H2, overexpression lines (K599-1302-HtC4H2). f Relative expression levels of HtC4H1 and HtC4H2 in normal and transgenic hairy roots determined by qPCR. **p < 0.01, *p < 0.05. g Determination of flavonoids in CK and OE of hairy roots