Plastome characteristics and species identification of Chinese medicinal wintergreens (Gaultheria, Ericaceae).

Wintergreen oil is a folk medicine widely used in foods, pesticides, cosmetics and drugs. In China, nine out of 47 species within Gaultheria (Ericaceae) are traditionally used as Chinese medicinal wintergreens; however, phylogenetic approaches currently used to discriminating these species remain unsatisfactory. In this study, we sequenced and characterized plastomes from nine Chinese wintergreen species and identified candidate DNA barcoding regions for Gaultheria. Each Gaultheria plastome contained 110 unique genes (76 protein-coding, 30 tRNA, and four rRNA genes). Duplication of trnfM, rps14, and rpl23 genes were detected, while all plastomes lacked ycf1 and ycf2 genes. Gaultheria plastomes shared substantially contracted SSC regions that contained only the ndhF gene. Moreover, plastomes of Gaultheria leucocarpa var. yunnanensis contained an inversion in the LSC region and an IR expansion to cover the ndhF gene. Multiple rearrangement events apparently occurred between the Gaultheria plastomes and those from several previously reported families in Ericales. Our phylogenetic reconstruction using 42 plastomes revealed well-supported relationships within all nine Gaultheria species. Additionally, seven mutational hotspot regions were identified as potential DNA barcodes for Chinese medicinal wintergreens. Our study is the first to generate complete plastomes and describe the structural variations of the complicated genus Gaultheria. In addition, our findings provide important resources for identification of Chinese medicinal wintergreens.

Characterization of the Complete Chloroplast Genome of Gaultheria nummularioides D.Don 1825 (Ericaceae).

Gaultheria nummularioides D.Don 1825 (Ericaceae) is a traditional Chinese medicinal plant used to treat rheumatoid arthritis. The complete chloroplast genome of G. nummularioides has been sequenced and assembled. The genome is 176,207 bp in total with one large single copy (LSC: 107,726 bp), one small single copy (SSC: 3,389 bp), and two inverted repeat regions (IRa and IRb; each 32,546 bp). The chloroplast genome encoded a total of 110 unique genes; the GC content of these genes is 36.6%. The results based on phylogenetic analysis of the complete chloroplast genome suggests that G. nummularioides diverged later than G. praticola, the sister relationship between G. nummularioides and the clade comprising G. fragrantissima Wall. 1820 and G. hookeri C.B. Clarke 1882 was strongly supported. This study provides additional information on the genetic diversity of G. nummularioides, its closely related taxa, and further exploration of chloroplast genomes in the Ericaceae family.

Characterization of the complete plastid genome of Gaultheria griffithiana (Ericaceae).

Gaultheria griffithiana is an evergreen shrub in the family Ericaceae. It is used as a source of the Chinese traditional medicine, Tougucao, with distribution of the junction of eastern Himalaya and Hengduan Mountain. The chloroplast genome of G. griffithiana is 175,649 bp in length with 135 genes, including eight rRNA genes, 39 tRNA genes, and 85 protein-coding genes. Phylogenetic analysis has converged on the placement of G. griffithiana as sister to G. praticola, G. nummularioides, and G. hookeri within the Leucothoides clade of Gaultheria in this study.

The complete chloroplast genome of Gaultheria fragrantissima Wall. (Ericaceae) from Yunnan, China, an aromatic medicinal plant in the wintergreens.

Gaultheria fragrantissima (Ericaceae) is an aromatic medicinal plant with high concentrations of the secondarymetabolite methyl salicylate (oil of wintergreen). In this study, the complete chloroplast genomeof G. fragrantissima was sequenced. The complete plastome is 176,196 bp in length, and the GCcontent is 36.6%. The plastome comprises 110 unique genes (76 protein-coding, 30 tRNA and 4 rRNA).Phylogenetic analysis fully supported a sister relationship between G. fragrantissima and G. hookeriwithin the Leucothoides clade of Gaultheria. This chloroplast genome will serve as a valuable referencefor future taxonomic and phylogenetic research.

Adaptation in the Dorsal Belt and Core Regions of the Auditory Cortex in the Awake Rat.

The rat auditory cortex is divided anatomically into several areas, but little is known about the functional differences in information processing among these areas. Three tonotopically organized core fields, namely, the primary (A1), anterior (AAF), and ventral (VAF) auditory fields, as well as one non-tonotopically organized belt field, the dorsal belt (DB), were identified based on their response properties. Compared to neurons in A1, AAF and VAF, units in the DB exhibited little or no response to pure tones but strong responses to white noise. The few DB neurons responded to pure tones with thresholds greater than 60 dB SPL, which was significantly higher than the thresholds of neurons in the core regions. In response to white noise, units in DB showed significantly longer latency and lower peak response, as well as longer response duration, than those in the core regions. Responses to repeated white noise were also examined. In contrast to neurons in A1, AAF and VAF, DB neurons could not follow repeated stimulation at a 300 ms inter-stimulus interval (ISI) and showed a significant steeper ISI tuning curve slope when the ISI was increased from 300 ms to 4.8 s. These results indicate that the DB processes auditory information on broader spectral and longer temporal scales than the core regions, reflecting a distinct role in the hierarchical cortical pathway.

ABORTED GAMETOPHYTE 1 is required for gametogenesis in Arabidopsis.

In flowering plants, the male and female gametogenesis is a crucial step of sexual reproduction. Although many genes have been identified as being involved in the gametogenesis process, the genetic mechanisms underlying gametogenesis remains poorly understood. We reported here characterization of the gene, ABORTED GAMETOPHYTE 1 (AOG1) that is newly identified as essential for gametogenesis in Arabidopsis thaliana. AOG1 is expressed predominantly in reproductive tissues including the developing pollen grains and ovules. The AOG1 protein shares no significant amino acid sequence similarity with other documented proteins and is located mainly in nuclei of the cells. Mutation in AOG1 caused degeneration of pollen at the uninucleate microspore stage and severe defect in embryo sacs, leading to a significant reduction in male and female fertility. Furthermore, the molecular analyses showed that the aog1 mutant significantly affected the expression of several genes, which are required for gametogenesis. Our results suggest that AOG1 plays important roles in gametogenesis at the stage prior to pollen mitosis I (PMI) in Arabidopsis, possibly through collaboration with other genes.