[Effect of temperature on content of baicalin and expression of key enzyme genes in callus of Scutellaria baicalensis].

The study is aimed to explore the effect of different temperature on the content of baicalin and gene expression in the growth of Scutellaria baicalensis. Four culture temperatures were used to establish the callus culture of S. baicalensis under dark conditions for 40 days and once every 5 days. The growth and baicalin contents were determined. 18S RNA was used as a reference gene to analyze the five key factors in baicalin biosynthesis pathway (PAL), cinnamic acid 4-hydroxylase (C4H), chalcone synthase (CHS), β-glucuronidase (GUS), baicalein-7- O -glucuronosyltransferase (UBGAT) gene expression levels. The results showed that biomass, baicalin content and accumulation increased with the increase of temperature. 25 °C and 30 °C were more suitable for the growth of S. baicalensis. The content and accumulation of baicalin at 25 °C reached the highest level at 30 days, reaching 2.75% and 12.44 mg, respectively. The relative expression levels of C4H, CHS, GUS and UGBAT genes at 15 °C were higher than those at other treatments. The correlation between the relative expression levels of each key enzyme and the content of baicalin was negatively correlated with the increase of incubation temperature. The relative expression levels of PAL, C4H and CHS genes at 25 °C and 30 °C were significantly correlated with the contents of baicalin and reached a highly significant or significant level. Relative low temperature conditions were not conducive to the growth of S. baicalensis and the accumulation of baicalin. The accumulation of baicalin by PAL and C4H in the upstream of the synthetic pathway was significant.