[Significant impact of different induction conditions on metabolic diversity of callus cell lines of Glycyrrhiza sp].

The purpose of this study was to evaluate the impact of callus induction and culture conditions on secondary metabolic diversity of the callus cell lines of traditional Chinese medicinal plant Glycyrrhiza sp. (Glycyrrhiza) by combined chemical analysis and HPLC fingerprint. These callus induction conditions included two Glycyrrhiza species, two types of explants, light and dark conditions, and two combinations of hormones. The evaluation was firstly based on the contents of total flavonoids in the callus by chemical analysis and one way ANOVA. The content of total flavonoids in callus was significantly (P < 0.05) influenced by Glycyrrhiza species, light condition, and the combination of hormones. The callus was further evaluated using diversity factor based on the comparison of HPLC fingerprints of these callus cell lines. Diversity factor varies significantly for calli induced under different conditions, with the highest being at 0.45 under light condition and combination of hormones. These results provide important knowledge for the selection of suitable callus cell lines for the production of pharmacologically important secondary metabolites or bioactive fractions by in vitro culture of Glycyrrhiza sp.

Vertical differentiation of soil organic carbon in mature natural forests in China.

We analyzed the effects of meteorological factors and soil properties on vertical variation of SOC, based on soil organic carbon (SOC) density in different soil layers (0-10, 10-20, 20-30, 30-50, and 50-100 cm) from 131 mature natural forests in different climate zones in China. The results showed that SOC density decreased with increasing soil depth (0-30 cm) in temperate coniferous, temperate deciduous broadleaved, subtropical deciduous broadleaved and subtropical evergreen broadleaved forests. There were significant regional variations of SOC density in 0-100 cm soil layer. SOC density of 0-100 cm soil layer in temperate coniferous forests was higher than temperate deciduous broadleaved forests, and was higher in subtropical evergreen broadleaved forests than subtropical deciduous broadleaved forests. SOC density was significantly positively correlated with soil clay content, mean annual precipitation, and aboveground net primary production, and significantly negatively correlated with soil pH and mean annual temperature. Mean annual precipitation and mean annual temperature influenced input and output of SOC, while soil pH and clay content affected SOC accumulation. Therefore, protecting mature natural coniferous and evergreen broadleaved forests would benefit forest carbon sequestration in China.