@article{zhou_shi_xie_2012, title={Regulation of anthocyanin biosynthesis by nitrogen in TTG1-GL3/TT8-PAP1-programmed red cells of Arabidopsis thaliana}, volume={236}, ISSN={["1432-2048"]}, DOI={10.1007/s00425-012-1674-2}, abstractNote={Nitrogen nutrients can regulate anthocyanin biosynthesis in Arabidopsis thaliana. In this investigation, we report the nitrogen regulation of anthocyanin biosynthesis activated by TTG1-GL3/TT8-PAP1 in red pap1-D cells. To understand the mechanisms of nitrogen regulation, we employed red pap1-D cells and wild-type cells (as a control) to examine the effects of different nitrogen treatments on anthocyanin biosynthesis. In general, the higher concentrations of ammonium and high total nitrogen tested (e.g., 58.8 and 29.8 mM total nitrogen consisting of NH(4)NO(3) and KNO(3)) reduced the levels and molecular diversity of anthocyanins; in contrast, the lower concentrations of ammonium and total nitrogen conditions (e.g., 9.4 mM KNO(3) and the depletion of nitrogen) increased the levels and molecular diversity of anthocyanins. An expression analysis of the main regulatory and pathway genes showed that at conditions of higher concentrations of ammonium and total nitrogen, the expression levels of PAP1 and TT8 decreased, but the expression levels of LBD37, 38 and 39, three negative regulators of anthocyanin biosynthesis, increased. In addition, the expression levels of the main pathway genes decreased. In contrast, at conditions of lower concentrations of ammonium and total nitrogen, the expression levels of PAP1, TT8 and the main pathway genes increased, whereas those of LBD37, 38 and 39 decreased. These results show that nitrogen regulation of anthocyanin biosynthesis in red cells undergoes a mechanism by which nitrogen controls the expression of genes encoding both main components of the TTG1-GL3/TT8-PAP1 complex and negative regulators. Based on these observations, we propose that the regulatory mechanism of nitrogen may occur via two pathways to control the expression of genes encoding positive and negative regulators in red pap1-D cells.}, number={3}, journal={PLANTA}, author={Zhou, Li-Li and Shi, Ming-Zhu and Xie, De-Yu}, year={2012}, month={Sep}, pages={825–837} }
 @article{alejos-gonzalez_qu_zhou_saravitz_shurtleff_xie_2011, title={Characterization of development and artemisinin biosynthesis in self-pollinated Artemisia annua plants}, volume={234}, ISSN={["1432-2048"]}, DOI={10.1007/s00425-011-1430-z}, abstractNote={Artemisia annua L. is the only natural resource that produces artemisinin (Qinghaosu), an endoperoxide sesquiterpene lactone used in the artemisinin-combination therapy of malaria. The cross-hybridization properties of A. annua do not favor studying artemisinin biosynthesis. To overcome this problem, in this study, we report on selection of self-pollinated A. annua plants and characterize their development and artemisinin biosynthesis. Self-pollinated F2 plants selected were grown under optimized growth conditions, consisting of long day (16 h of light) and short day (9 h of light) exposures in a phytotron. The life cycles of these plants were approximately 3 months long, and final heights of 30-35 cm were achieved. The leaves on the main stems exhibited obvious morphological changes, from indented single leaves to odd, pinnately compound leaves. Leaves and flowers formed glandular and T-shaped trichomes on their surfaces. The glandular trichome densities increased from the bottom to the top leaves. High performance liquid chromatography-mass spectrometry-based metabolic profiling analyses showed that leaves, flowers, and young seedlings of F2 plants produced artemisinin. In leaves, the levels of artemisinin increased from the bottom to the top of the plants, showing a positive correlation to the density increase of glandular trichomes. RT-PCR analysis showed that progeny of self-pollinated plants expressed the amorpha-4, 11-diene synthase (ADS) and cytochrome P450 monooxygenase 71 AV1 (CYP71AV1) genes, which are involved in artemisinin biosynthesis in leaves and flowers. The use of self-pollinated A. annua plants will be a valuable approach to the study of artemisinin biosynthesis.}, number={4}, journal={PLANTA}, author={Alejos-Gonzalez, Fatima and Qu, Guosheng and Zhou, Li-Li and Saravitz, Carole H. and Shurtleff, Janet L. and Xie, De-Yu}, year={2011}, month={Oct}, pages={685–697} }
 @article{feng_qu_zhou_xie_xiang_2009, title={Shoot regeneration of dwarf dogwood (Cornus canadensis L.) and morphological characterization of the regenerated plants}, volume={97}, ISSN={["1573-5044"]}, DOI={10.1007/s11240-009-9495-0}, number={1}, journal={PLANT CELL TISSUE AND ORGAN CULTURE}, author={Feng, Chun-Miao and Qu, Rongda and Zhou, Li-Li and Xie, De-Yu and Xiang, Qiu-Yun}, year={2009}, month={Apr}, pages={27–37} }
 @article{zhou_zeng_shi_xie_2008, title={Development of tobacco callus cultures over expressing Arabidopsis PAP1/MYB75 transcription factor and characterization of anthocyanin biosynthesis}, volume={229}, ISSN={0032-0935 1432-2048}, url={http://dx.doi.org/10.1007/s00425-008-0809-y}, DOI={10.1007/s00425-008-0809-y}, abstractNote={The Arabidopsis PAP1 gene (At1g56650) encodes the MYB75 transcription factor, which has been demonstrated to essentially regulate the biosynthesis of anthocyanins. Our previous study showed that ectopic expression of the PAP1 gene led to high pigmentation of anthocyanins in all tissues of transgenic tobacco plants. In order to understand the mechanisms of how PAP1 regulates anthocyanin biosynthesis and what can regulate the function of PAP1, we have established PAP1 transgenic tobacco callus cultures. Phenotypically different calli including anthocyanin-producing red and anthocyanin-free white calli lines were differentially induced from the same genotype of PAP1 transgenic plants. RT-PCR analysis showed that the expression of the PAP1 transgene was similar in the two types of calli, indicating that the transgenic red and white calli had differential responses to the regulation of PAP1. The growth of transgenic red calli followed a "sigmoid-like" curve in a 25-day callus culture period, during which the time course obviously impacted the profiles and the average levels of anthocyanins even though the expression of the PAP1 transgene was constitutive. A HPLC-UV-ESI-mass spectrum-based profiling characterized nine anthocyanin molecules (e.g., 595, 579 and 609 m/z) in the transgenic red calli over the course of the culture period. Cyanidin, pelargonidin, and peonidin were the major anthocyanidins identified by HPLC-mass spectrum analysis. We have demonstrated that dark, nitrogen nutrients, and auxin apparently affect the anthocyanin profiles in PAP1 transgenic callus cultures; and suggest that these cell cultures are an appropriate system to study the regulatory function of PAP1 on the anthocyanin biosynthesis at post-transcriptional level in vivo.}, number={1}, journal={Planta}, publisher={Springer Science and Business Media LLC}, author={Zhou, Li-Li and Zeng, Hai-Nian and Shi, Ming-Zhu and Xie, De-Yu}, year={2008}, month={Sep}, pages={37–51} }