Promoter variations in DBR2-like affect artemisinin production in different chemotypes of Artemisia annua

Artemisia annua is the only known plant source of the potent antimalarial artemisinin,which occurs as the low-and high-artemisinin producing(LAP and HAP)chemotypes.Nevertheless,the different mechanisms of artemisinin producing between these two chemotypes were still not fully understood.Here,we performed a comprehensive analysis of genome resequencing,metabolome,and transcriptome data to systematically compare the difference in the LAP chemotype JL and HAP chemotype HAN.Metabolites analysis revealed that 72.18%of sesquiterpenes was highly accumulated in HAN compared to JL.Integrated omics analysis found a DBR2-Like(DBR2L)gene may be involved in artemisinin biosynthesis.DBR2L was highly homologous with DBR2,belonged to ORR3 family,and had the DBR2 activity of catalyzing artemisinic aldehyde to dihydroartemisinic aldehyde.Genome resequencing and promoter cloning revealed that complicated variations existed in DBR2L promoters among different varieties of A.annua and were clustered into three variation types.The promoter activity of diverse variant types showed obvious differences.Furthermore,the core region(-625 to 0)of the DBR2L promoter was identified and candidate transcription factors involved in DBR2L regulation were screened.Thus,the result indicates that DBR2L is another key enzyme involved in artemisinin biosynthesis.The promoter variation in DBR2L affects its expression level,and thereby may result in the different yield of artemisinin in varieties of A.annua.It provides a novel insight into the mechanism of artemisinin-producing difference in LAP and HAP chemotypes of A.annua,and will assist in a high yield of artemisinin in A.annua.

Implications for photonic applications of diatom growth and frustule nanostructure changes in response to different light wavelengths

Diatoms are unicellular algae enclosed in intricate bio-silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano-scale structures of the frustule for utilization of diatoms in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an important role in mediating light for these biological functions, as well as being central for its nano-technological applications. In this study we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light （red, yellow, green and blue） at 300μmol photons m-2-s-1 resulted in a statistically significant change in nanostructure compared to white light. Green light at 100 μmol photon m-2.s-1 led to a significant decrease in mean frustule diameter and mean foramen diameter. Numerical simulations confirmed that the morphological changes obtained were sufficient to induce clear differences in the photonics properties of the frustule. The wavelength had no effect on the growth rate at high light intensity （300 μmol photons m-2.s-1）. However, at 100 μmol photons m-2.s-1, yellow, red-orange and green light resulted in significantly lower maximum growth rates than the other wavelengths. This response of the frustule structure to different light treatment indicates the possibility of a light-based frustule nanostructure manipulation method, which is simple and environmentally friendly.