The chromosome-level genome assembly of Cananga odorata provides insights into its evolution and terpenoid biosynthesis.

Cananga odorata is known as a natural perfume tree of the Annonaceae family in Magnoliales. However, its phylogenetic position and the molecular mechanisms involved in the biosynthesis of the floral volatile organic compounds (VOCs) remain unclear. Here, by combining a variety of sequencing platforms, we present a telomere-to-telomere (T2T) genome of C. odorata with 735.83 Mb, which represents the highest integrity and assembly quality of genome in magnoliid plants reported to date. Phylogenetic analysis based on multiple datasets and approaches showed that C. odorata, as a member of magnoliids, is sister to eudicots, after their divergence from monocots. Metabolomic of VOCs in the essential oil and flowers scent showed that sesquiterpenes, especially ß-caryophyllene, were the major compounds. Two CoTPS21 homologues derived from tandem duplication events were highly expressed during flower development and were identified as the key sesquiterpene synthases for the production of ß-caryophyllene. In addition, CoSPL3 and CoSPL9 were considered as potential transcription factors for activating the expression of CoTPS21 homologues. Our results shed light on the molecular mechanisms underlying the biosynthesis of the unique floral fragrance in C. odorata and provide new insights into the phylogenetic position of magnoliids.

An integrated high-resolution mapping shows congruent biodiversity patterns of Fagales and Pinales.

The documentation of biodiversity distribution through species range identification is crucial for macroecology, biogeography, conservation, and restoration. However, for plants, species range maps remain scarce and often inaccurate. We present a novel approach to map species ranges at a global scale, integrating polygon mapping and species distribution modelling (SDM). We develop a polygon mapping algorithm by considering distances and nestedness of occurrences. We further apply an SDM approach considering multiple modelling algorithms, complexity levels, and pseudo-absence selections to map the species at a high spatial resolution and intersect it with the generated polygons. We use this approach to construct range maps for all 1957 species of Fagales and Pinales with data compilated from multiple sources. We construct high-resolution global species richness maps of these important plant clades, and document diversity hotspots for both clades in southern and south-western China, Central America, and Borneo. We validate the approach with two representative genera, Quercus and Pinus, using previously published coarser range maps, and find good agreement. By efficiently producing high-resolution range maps, our mapping approach offers a new tool in the field of macroecology for studying global species distribution patterns and supporting ongoing conservation efforts.

Castanopsiscorallocarpus (Fagaceae), a new species from Royal Belum (Perak) in Peninsular Malaysia.

A new species from the Fagaceae family, Castanopsiscorallocarpus Tan & Strijk, is described from Royal Belum State Park in Peninsular Malaysia. Here, we provide technical illustrations, colour images and a description of its conservation status and the collecting locality, in addition to a comparative analysis with other species in the region. The solitary nut of C.corallocarpus has a morphologically unique cupule, lined with rows of thick coral-like spines not seen in other Castanopsis species.

Lithocarpustapanuliensis (Fagaceae), a new stone oak from northern Sumatra and its role as an important resource for critically endangered orangutans.

A new species of stone oak, Lithocarpustapanuliensis Harapan, W.H.Tan, Nurainas & Strijk from South Tapanuli, North Sumatra, Indonesia is described. We provide colour photographs, a distribution map and a new IUCN conservation status assessment for inclusion on the global Red List. The unique cupule morphology, particularly the shape, placement and distinctness of the cupule protuberances, are distinctive from other Lithocarpus species in the region. Ecological interactions (e.g. consumption and nesting) with Tapanuli orangutans were recorded in the field.

Genomics of the critically endangered monotypic genus Sinopora: the plastome of S. hongkongensis (Lauraceae).

Sinopora hongkongensis is a critically endangered endemic tree species restricted to Hong Kong. Here we report its plastome sequence. The S. hongkongensis plastome was 158,612 bp in length, with a large single-copy (LSC) region of 89,405 bp and a small single-copy (SSC) region of 18,205 bp, separated by two inverted repeat (IR) regions of 25,498 bp. It contained 126 genes, including 89 coding genes, 29 tRNA genes, and 8 rRNA genes. The overall GC content was 39.0%, and 43.0%, 37.7%, and 34.0%, in the IRs, LSC, and SSC regions, respectively. A phylogenetic analysis combining a subset of Lauraceae plastomes with closely related outgroup families confirms the placement of S. hongkongensis in Lauraceae and explores relationships with other genera in the family.

Plastome of Quercus xanthoclada and comparison of genomic diversity amongst selected Quercus species using genome skimming.

The genus Quercus L. contains several of the most economically important species for timber production in the Northern Hemisphere. It was one of the first genera described, but genetic diversity at a global scale within and amongst oak species remains unclear, despite numerous regional or species-specific assessments. To evaluate global plastid diversity in oaks, we sequenced the complete chloroplast of Quercus xanthoclada and compared its sequence with those available from other main taxonomic groups in Quercus. We quantify genomic divergence amongst oaks and performed a sliding window analysis to detect the most variable regions amongst members of the various clades, as well as divergent regions occurring in specific pairs of species. We identified private and shared SNPs amongst oaks species and sections and stress the need for a large global assessment of genetic diversity in this economically and ecologically important genus.

Exploring evolution and diversity of Chinese Dipterocarpaceae using next-generation sequencing.

Tropical forests, a key-category of land ecosystems, are faced with the world's highest levels of habitat conversion and associated biodiversity loss. In tropical Asia, Dipterocarpaceae are one of the economically and ecologically most important tree families, but their genomic diversity and evolution remain understudied, hampered by a lack of available genetic resources. Southern China represents the northern limit for Dipterocarpaceae, and thus changes in habitat ecology, community composition and adaptability to climatic conditions are of particular interest in this group. Phylogenomics is a tool for exploring both biodiversity and evolutionary relationships through space and time using plastome, nuclear and mitochondrial genome. We generated full plastome and Nuclear Ribosomal Cistron (NRC) data for Chinese Dipterocarpaceae species as a first step to improve our understanding of their ecology and evolutionary relationships. We generated the plastome of Dipterocarpus turbinatus, the species with the widest distribution using it as a baseline for comparisons with other taxa. Results showed low level of genomic diversity among analysed range-edge species, and different evolutionary history of the incongruent NRC and plastome data. Genomic resources provided in this study will serve as a starting point for future studies on conservation and sustainable use of these dominant forest taxa, phylogenomics and evolutionary studies.

The first complete chloroplast genome of a major mangrove species Sonneratia alba Sm. and its implications on conservation efforts.

Sonneratia alba Sm. is one of the most widely distributed mangrove species worldwide. In this study, the whole chloroplast genome of S. alba was assembled for the first time not only in Sonneratia, but also for a member of the mangrove plant community. The total chloroplast genome was 153,061 bp in length, with a large single copy (LSC) region of 87,226 bp and a small single copy (SSC) region of 18,033 bp, separated by two inverted repeats (IRs) regions of 23,901 bp. The overall GC content was 37.3%, and 43.1%, 35.4%, and 31.1% in the IRs, LSC, and SSC regions, respectively. It contained 106 genes, including 79 coding genes, 24 tRNA genes, and four rRNA genes. A phylogenetic analysis confirmed that S. alba was clustered with Trapa maximowiczii within the family Lythraceae.

A taxonomic study of Quercus langbianensis complex based on morphology and DNA barcodes of classic and next generation sequences.

The taxonomy of Quercus langbianensis and its relatives in Vietnam and Cambodia have been revised based on evidence obtained from field observations, morphological comparison of herbarium specimens and molecular analyses using both classic and next generation DNA markers. Based on Bayesian inference using rbcL, matK and ITS regions and Neighbour-joining tree using genome-wide sequences amplified with multiplexed inter-simple sequence repeat (ISSR) primers (MIG-seq), the authors recognised ten species in the complex in Vietnam and Cambodia, three of which are newly described in this paper: Q. baolamensissp. nov., Q. bidoupensissp. nov. and Q. honbaensissp. nov. These new species are all phenotypically similar to Q. langbianensiss. str. in having lanceolate to oblanceolate leaf shape, upper 4-5/6-serrated leaf margin, acute or acuminate leaf apex and bracts of cupule arranged in 5-9 rings but distinguished both morphologically and phylogenetically. In molecular phylogenetic reconstructions, Q. bidoupensis is not close to any other species. In the Bayesian tree, Q. honbaensis is sister to both Q. blaoensis and Q. camusiae that are found in the same locality but morphologically distinct and those three species are sister to Q. langbianensiss. str., while Quercus baolamensis is not sister to Q. langbianensiss. str. in both the Bayesian tree and MIG-seq tree. In addition, Q. cambodiensis and Q. baniensis previously reduced to Q. langbianensiss. lat. have been recognised as distinct species. Six species were in need of lectotypification and that is undertaken herein.

The chloroplast genome sequence of Michelia alba (Magnoliaceae), an ornamental tree species.

Magnoliaceae are both economically and ornamentally important trees. Despite extensive studies in this family, the taxonomy of Michelia L. remains unclear, as well as the taxonomical status of Michelia alba. Herein, we report the complete chloroplast genome of M. alba DC. The chloroplast genome was 159,789 bp in length, with a large single-copy (LSC) region of 87,951 bp and a small single-copy (SSC) region of 18,798 bp, separated by two inverted repeat (IRs) regions of 26,570 bp. It contained 156 genes, including 83 coding genes, 68 tRNA genes, and 8 rRNA genes. The overall GC content was 39.3%, and 43.2%, 38.0%, 34.3%, in the IRs, LSC, and SSC regions, respectively. A phylogenetic analysis showed that M. alba is closely related to M. odora, with the genus Michelia nested inside Magnolia.

The first complete chloroplast sequence of a major tropical timber tree in the Meranti family: Vatica odorata (Dipterocarpaceae).

Dipterocarpaceae are one of the economically most important native tree families for timber production in tropical Asia. We report the complete chloroplast genome of Vatica odorata (Griff.) Symington, the first in the family Dipterocarpaceae. The chloroplast genome was 151,465 bp in length, with a large single-copy (LSC) region of 83,538 bp and a small single-copy (SSC) region of 20,095 bp, separated by two inverted repeat (IRs) regions of 23,916 bp. It contained 126 genes, including 90 coding genes, 30 tRNA genes, and 8 rRNA genes. The overall GC content was 37.2%, and 43.1%, 35.2%, and 33.3% in the IRs, LSC and SSC regions, respectively. A phylogenetic tree showed Vatica accumulated more variation when compared with Tilia, and that internal relationships in Malvales need to be reassessed.

Comparison of intraspecific, interspecific and intergeneric chloroplast diversity in Cycads.

Cycads are among the most threatened plant species. Increasing the availability of genomic information by adding whole chloroplast data is a fundamental step in supporting phylogenetic studies and conservation efforts. Here, we assemble a dataset encompassing three taxonomic levels in cycads, including ten genera, three species in the genus Cycas and two individuals of C. debaoensis. Repeated sequences, SSRs and variations of the chloroplast were analyzed at the intraspecific, interspecific and intergeneric scale, and using our sequence data, we reconstruct a phylogenomic tree for cycads. The chloroplast was 162,094 bp in length, with 133 genes annotated, including 87 protein-coding, 37 tRNA and 8 rRNA genes. We found 7 repeated sequences and 39 SSRs. Seven loci showed promising levels of variations for application in DNA-barcoding. The chloroplast phylogeny confirmed the division of Cycadales in two suborders, each of them being monophyletic, revealing a contradiction with the current family circumscription and its evolution. Finally, 10 intraspecific SNPs were found. Our results showed that despite the extremely restricted distribution range of C. debaoensis, using complete chloroplast data is useful not only in intraspecific studies, but also to improve our understanding of cycad evolution and in defining conservation strategies for this emblematic group.