Lycium chinense Mill, an important Chinese herbal medicine, is widely used as a dietary supplement and food. Here the chloroplast (CP) genome of L. chinense was sequenced and analyzed, revealing a size of 155,756 bp and with a 37.8% GC content. The L. chinense CP genome comprises a large single copy region (LSC) of 86,595 bp and a small single copy region (SSC) of 18,209 bp, and two inverted repeat regions (IRa and IRb) of 25,476 bp separated by the single copy regions. The genome encodes 114 genes, 16 of which are duplicated. Most of the 85 protein-coding genes (CDS) had standard ATG start codons, while 3 genes including rps12, psbL and ndhD had abnormal start codons (ACT and ACG). In addition, a strong A/T bias was found in the majority of simple sequence repeats (SSRs) detected in the CP genome. Analysis of the phylogenetic relationships among 16 species revealed that L. chinense is a sister taxon to Lycium barbarum. Overall, the complete sequence and annotation of the L. chinense CP genome provides valuable genetic information to facilitate precise understanding of the taxonomy, species and phylogenetic evolution of the Solanaceae family.

In the last decade, several studies have relied on a small number of plastid genomes to deduce deep phylogenetic relationships in the species-rich Myrtaceae. Nevertheless, the plastome of Rhodomyrtus tomentosa, an important representative plant of the Rhodomyrtus (DC.) genera, has not yet been reported yet. Here, we sequenced and analyzed the complete chloroplast (CP) genome of R. tomentosa, which is a 156,129-bp-long circular molecule with 37.1% GC content. This CP genome displays a typical quadripartite structure with two inverted repeats (IRa and IRb), of 25,824 bp each, that are separated by a small single copy region (SSC, 18,183 bp) and one large single copy region (LSC, 86,298 bp). The CP genome encodes 129 genes, including 84 protein-coding genes, 37 tRNA genes, eight rRNA genes and three pseudogenes (ycf1, rps19, ndhF). A considerable number of protein-coding genes have a universal ATG start codon, except for psbL and ndhD. Premature termination codons (PTCs) were found in one protein-coding gene, namely atpE, which is rarely reported in the CP genome of plants. Phylogenetic analysis revealed that R. tomentosa has a sister relationship with Eugenia uniflora and Psidium guajava. In conclusion, this study identified unique characteristics of the R. tomentosa CP genome providing valuable information for further investigations on species identification and the phylogenetic evolution between R. tomentosa and related species.

Background: Helicteres angustifolia has long been used in Chinese traditional medicine. It has multiple pharmacological benefits, including anti-inflammatory, anti-viral and anti-tumor effects. Its main active chemicals include betulinic acid, oleanolic acid, helicteric acid, helicterilic acid, and other triterpenoid saponins. It is worth noting that some acylated triterpenoids, such as helicteric acid and helicterilic acid, are characteristic components of Helicteres and are relatively rare among other plants. However, reliance on natural plants as the only sources of these is not enough to meet the market requirement. Therefore, the engineering of its metabolic pathway is of high research value for enhancing the production of secondary metabolites. Unfortunately, there are few studies on the biosynthetic pathways of triterpenoids in H. angustifolia, hindering its further investigation. Results: Here, the RNAs of different groups treated by metabolic stimulation were sequenced with an Illumina high-throughput sequencing platform, resulting in 121 gigabases of data. A total of 424,824 unigenes were obtained after the trimming and assembly of the raw data, and 22,430 unigenes were determined to be differentially expressed. In addition, three oxidosqualene cyclases (OSCs) and four Cytochrome P450 (CYP450s) were screened, of which one OSC (HaOSC1) and one CYP450 (HaCYPi3) achieved functional verification, suggesting that they could catalyze the production of lupeol and oleanolic acid, respectively. Conclusion: In general, the transcriptomic data of H. angustifolia was first reported and analyzed to study functional genes. Three OSCs, four CYP450s and three acyltransferases were screened out as candidate genes to perform further functional verification, which demonstrated that HaOSC1 and HaCYPi3 encode for lupeol synthase and β-amyrin oxidase, which produce corresponding products of lupeol and oleanolic acid, respectively. Their successful identification revealed pivotal steps in the biosynthesis of acylated triterpenoids precursors, which laid a foundation for further study on acylated triterpenoids. Overall, these results shed light on the regulation of acylated triterpenoids biosynthesis.