The complete chloroplast genome and phylogenetic analysis of Jacobaea maritima (Asteraceae).

Jacobaea maritima is an important horticulture plant in the genus Jacobaea. Here, we assembled the complete chloroplast genome of J. maritima. The chloroplast genome was 153,857 bp in length, with a pair of inverted repeat regions (IRs) (27,936 bp) separated by a large single-copy region (LSC) (82,771 bp) and a small single-copy region (SSC) (15,214 bp). The complete chloroplast genome contained 112 unique genes, including 79 protein-coding genes, 29 tRNA genes, and 4 rRNA genes. The phylogenetic analysis showed Jacobaea was more closely related to Senecio, Crassocephalum and Gynura. The chloroplast genome of J. maritima can provide data to support future phylogenetic studies of Jacobaea.

The complete chloroplast genome of Angelonia angustifolia Benth. (Plantaginaceae), an ornamental and medicinal plant.

In this study, we assembled and characterized the complete chloroplast (cp) genome of Angelonia angustifolia Benth., 1846, a herbaceous and perennial plant, native to Latin America. It is an ornamental and medicinal plant that showed bright prospects for application. The cp genome of A. angustifolia has a typical conserved quadripartite structure of 154,316 bp in total length. The genome includes a large single-copy (LSC) region (84,110 bp), a small single-copy (SSC) region (15,950 bp), and a pair of inverted repeat (IR) regions (27,128 bp). The cp genome contains 130 genes comprising 85 protein-coding, 37 tRNA, and 8 rRNA genes. Phylogenetic analysis indicates that A. angustifolia is closely related to Bacopa monnieri, Scoparia dulcis, and Limnophila sessiliflora in the Plantaginaceae. Taken together, the complete cp genomes of A. angustifolia provided significant insights and important information for molecular biology, evolution, and taxonomy in the genus Angelonia.

Complete chloroplast genome sequence of a bulbous flowering plant, Allium triquetrum Linnaeus, 1753 (Amaryllidaceae).

Allium triquetrum (Linnaeus, 1753) is a bulbous flowering plant of the genus Allium (Amaryllidaceae), native to the Mediterranean basin, and is now widespread and invasive in different parts of the world via ornamental horticultural trade. However, to date, the genomic study of A. triquetrum has lagged, which impedes the development of appropriate utilization and management practices for this species. Here, we report the complete chloroplast genome sequence of A. triquetrum. The chloroplast genome size of A. triquetrum was 153,298 bp, consisting of a pair of inverted repeat regions (26,547 bp), separated by a large single-copy (82,875 bp) region and a small single-copy (17,329 bp) region. Genome annotation predicted 133 genes, including 87 protein-coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic analysis based on 60 whole chloroplast genome sequences of Allium species suggested that A. triquetrum and A. moly are sister to each other along with the clade of A. fasciculatum, A. hookeri, and A. macranthum.

The complete chloroplast genome of Osteospermum ecklonis (DC.) Norl. (Asteraceae: Asterodae: Calenduleae), an ornamental plant.

Osteospermum ecklonis (DC.) Norl. 1838 is a herbaceous and perennial plant native to South Africa. It is an ornamental plant that shows great commercial potential. In the present study, the complete chloroplast (cp) genome was 151,295 bp in total length, and 127 genes were identified, including 85 protein-coding, 34 tRNA, and eight rRNA genes. The cp genome includes a large single-copy (LSC) region of 83,293 bp, a small single-copy (SSC) region of 18,012 bp, and a pair of inverted repeats (IRs) regions of 24,995 bp. The phylogenetic relationship of O. ecklonis revealed by cp genome provides a foundation for future studies of the phylogeny in the Asteraceae.

The complete chloroplast genome of Mediterranean shrub Teucrium fruticans L. (Lamiaceae; Subfam. Lamioideae).

Teucrium fruticans L. is a shrub in Lamiaceae that is native to Mediterranean countries where it is used in medicine ornamental gardens. Here, we report the complete chloroplast genome of T. fruticans which is 150,808 bp in length, with a pair of inverted repeat regions (IRs) (25,597 bp) separated by a large single-copy area (LSC) (82,634 bp) and a small single-copy area (SSC) (16,912 bp). The completed chloroplast genome of T. fruticans comprises 130 unique genes, including 86 protein-coding genes, 36 tRNA genes, and eight rRNA genes. The results of the phylogenetic analysis significantly supported the grouping of T. fruticans with nine Teucrium species. The complete chloroplast genome of T. fruticans can provide a powerful tool to accelerate breeding, biotechnological and phylogenetic study.

Integrated Proteomic and Metabolomic Analyses Provide Insights Into Acquisition of Embryogenic Ability in Agapanthus praecox.

Somatic embryogenesis (SE) is an ideal model for plant cell totipotency. Transition from somatic cells to embryogenic cells is the key to SE. The poor frequency of embryogenic callus (EC) induction has limited the application of SE in many plants, such as Agapanthus praecox. We performed large-scale, quantitative proteomic and metabolomic analyses with different callus differentiation directions (SE and organogenesis) and stages (initial SE and repetitive SE) to better understand the morphological, physiological, and molecular characteristics of the acquisition of embryogenic ability in A. praecox. Integrated proteomic and metabolomic analyses suggested that callus differentiation direction was potentially regulated by pathways related to carbohydrate and energy metabolism (fatty acid metabolism, pyruvate metabolism, glycolysis/gluconeogenesis, pentose and glucuronate interconversions, starch and sucrose metabolism, galactose metabolism, carbon fixation pathways in prokaryotes, carbohydrate digestion and absorption, and fructose and mannose metabolism), chromatin accessibility and DNA methylation, reactive oxygen species responses and resistance (ascorbate and aldarate metabolism), and plant hormonal signaling. As a validation, we found that carbon source combination and plant hormone regulation in the culture medium significantly affected the acquisition of embryogenic ability, thereby inducing EC. Interestingly, plant hormonal signaling-related genes showed different expression patterns significantly when callus cultured with different carbon sources. Thus, our results suggested that energy supply and hormone signal transduction seemed to cooperatively contribute to the activation of embryogenic ability. Altogether, this study revealed valuable information regarding the molecular and biochemical changes that occurred during EC induction and provided valuable foundation for comprehensive understanding of the mechanisms associated with SE and organogenesis in A. praecox.

Ethylene-regulated immature fruit abscission is associated with higher expression of CoACO genes in Camellia oleifera.

Immature fruit abscission is a key limiting factor in Camellia oleifera Abel. (C. oleifera) yield. Ethylene is considered to be an important phytohormone in regulating fruit abscission. However, the molecular mechanism of ethylene in regulating fruit abscission in C. oleifera has not yet been studied. Here, we found that the 1-aminocyclopropane-1-carboxylic acid (ACC) content was significantly increased in the abscission zones (AZs) of abnormal fruits (AF) which were about to abscise when compared with normal fruits (NF) in C. oleifera 'Huashuo'. Furthermore, exogenous ethephon treatment stimulated fruit abscission. The cumulative rates of fruit abscission in ethephon-treated fruits (ETH-F) on the 4th (35.0%), 8th (48.7%) and 16th (57.7%) days after treatment (DAT) were significantly higher than the control. The ACC content and 1-aminocyclopropane-1-carboxylate oxidase (ACO) activity in AZs of ETH-F were also significantly increased when compared with NF on the 4th and 8th DAT. CoACO1 and CoACO2 were isolated in C. oleifera for the first time. The expressions of CoACO1 and CoACO2 were considerably upregulated in AZs of AF and ETH-F. This study suggested that ethylene played an important role in immature fruit abscission of C. oleifera and the two CoACOs were the critical genes involved in ethylene's regulatory role.

The complete chloroplast genome of Agrimonia pilosa var. nepalensis (D. Don) Nakai.

Agrimonia pilosa var. nepalensis (D. Don) Nakai is an herbaceous species of Rosaceae distributed in China. It has ornamental and ecological values. Lack of genetic background seriously hinders its further research and utilization. To provide genetic information for further study of it, complete chloroplast (cp) genome was characterized in this study. The genome is a circular molecule of 155,147 bp in length with overall GC content of 36.9%, which contains 85 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. It contains a typical tetrad structure, including a large single copy, a small single copy, and two inverted repeat regions. Phylogenetic analysis revealed that A. pilosa var. nepalensis and A. pilosa are closely related. Result of this study could provide genetic information for further research of A. pilosa var. nepalensis.

Full-Length Transcriptome from Camellia oleifera Seed Provides Insight into the Transcript Variants Involved in Oil Biosynthesis.

Camellia oleifera Abel., belonging to the genus Camellia of Theaceae, has been widely used as a cooking oil, lubricant, and in cosmetics. Because of complicated polyploidization and large genomes, reference genome information is still lacking. Systematic characterization of gene models based on transcriptome data is a fast and economical approach for C. oleifera. Pacific Biosciences single-molecule long-read isoform sequencing (Iso-Seq) and Illumina RNA-Seq combined with gas chromatography were performed for exploration of oil biosynthesis, accumulation, and comprehensive transcriptome analysis in C. oleifera seeds at five different developmental stages. We report the first full-length transcriptome data set of C. oleifera seeds comprising 40,143 deredundant high-quality isoforms. Among these isoforms, 37,982 were functionally annotated, and 271 (2.43%) belonged to fatty acid metabolism. A total of 8,344 full-length unique transcript models were obtained, and 8,151 (97.69%) of them produced more than two isoforms, suggesting a high degree of transcriptome complexity in C. oleifera seeds. A total of 783 alternative splicing (AS) events were identified, among which the retained intron was the most abundant. We also obtained 1,910 long noncoding RNAs (lncRNAs) and found that AS events occurred in these lncRNAs. Potential transcript variants of genes involved in oil biosynthesis were also investigated. After performing weighted correlation network analysis, we found seven "gene modules" and hub genes for each module showing a significant association with oil content. The series test of clusters classified these modules into four significant profiles based on gene expression patterns. Protein-protein interaction network analysis showed that upregulated WRI1 interacted with 17 genes encoding the enzymes playing key roles in oil synthesis. MYB and ZIP transcriptional factors also showed significant interactions with key genes involved in oil synthesis. Collectively, our data advance the knowledge of RNA isoform diversity in seeds at different developmental stages and provide a rich resource for functional studies on oil synthesis in C. oleifera.