ABSTRACT
Trees of Engelhardia are important components of subtropical and tropical forests in South-eastern Asia with great ecological and economic values. However, phylogenetic relationships within Engelhardioideae (Juglandaceae) remains obscure. In this study, we report the first complete chloroplast genome sequences of Engelhardia sensu stricto, Engelhardia hainanensis Chen, a rare species endemic in southern China. Its complete chloroplast genome is 161,574 bp in length, with a typical quadripartite structure that includes a large single-copy region of 91,158 bp, a small single-copy region of 18,790 bp, and its GC content is 35.8%. A total of 128 genes were identified, including 83 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Furthermore, a phylogenetic tree of Juglandaceae was constructed based the complete chloroplast genome sequence, which strongly support the three-subfamily classification system in Juglandaceae, and E. hainanensis was resolved sister to two Alfaropsis species. This study provides valuable genomic information for the species identification and phylogenetic study of Juglandaceae.
ABSTRACT
Characterizing genetic diversity and structure and identifying conservation units are both crucial for the conservation and management of threatened species. The development of high-throughput sequencing technology provides exciting opportunities for conservation genetics. Here, we employed the powerful SuperGBS method to identify 33, 758 high-quality single-nucleotide polymorphisms (SNP) from 134 individuals of a critically endangered montane shrub endemic to North China, Lonicera oblata. A low level of genetic diversity and a high degree of genetic differentiation among populations were observed based on the SNP data. Both principal component and phylogenetic analyses detected seven clusters, which correspond exactly to the seven geographic populations. Under the optimal K = 7, Admixture suggested the combination of the two small and geographically neighboring populations in the Taihang Mountains, Dongling Mountains, and Lijiazhuang, while the division of the big population of Jiankou Great Wall in the Yan Mountains into two clusters. High population genetic diversity and a large number of private alleles were detected in the four large populations, while low diversity and non-private alleles were observed for the remaining three small populations, implying the importance of these large populations as conservation units in priority. Demographic history inference suggested two drastic contractions of population size events that occurred after the Middle Pleistocene Transition and the Last Glacial Maximum, respectively. Combining our previous ecological niche modeling results with the present genomic data, there was a possible presence of glacial refugia in the Taihang and Yan Mountains, North China. This study provides valuable data for the conservation and management of L. oblata and broadens the understanding of the high biodiversity in the Taihang and Yan Mountains.
ABSTRACT
BACKGROUND: Plants in cliff habitats may evolve specific reproductive strategies to cope with harsh environments, and unraveling these reproductive characteristics can improve our understanding of survival strategies and lithophyte evolution. This understanding is especially important for efforts to protect rare and endemic plants. Here, we investigated the reproductive biology of Lonicera oblata, an endangered lithophytic shrub that is scattered in highly fragmented and isolated cliff habitats of the Taihang and Yan mountains in North China. RESULTS: Flowers of L. oblata are herkogamous and protandrous, characteristics that can prevent autogamy at the single-flower level, and insects are necessary for pollination. The outcrossing index, pollen/ovule ratio, and the results of hand pollination were measured and all revealed a mixed mating system for L. oblata, that combines cross-fertilization and partial self-fertilization. The floral traits of L. oblata of zygomorphic and brightly yellowish corolla, heavy fragrance, and rich nectar, suggest an entomophilous pollination system. Sweat bees were observed as the most effective pollinators but their visiting frequencies were not high. Pollen limitation may limit the reproductive success of L. oblata. CONCLUSIONS: We determined the reproductive characteristics of L. oblata, a critically endangered species endemic to cliffs in North China, providing insight into its endangerment and suggesting conservation strategies. L. oblata has highly pollinator-dependent self-fertilization as part of a mixed mating system. Floral features such as low-flowering synchrony, asynchronous anthers dehiscence, and high duration of stigma receptivity, improve pollination efficiency in the case of low pollinator service. Our work provides reference information to understand the survival strategies and conservation of L. oblata and other lithophytes.
Subject(s)
Flowers/physiology , Insecta , Lonicera/growth & development , Animals , Body Size , China , Conservation of Natural Resources/methods , Ecosystem , Endangered Species , Flowers/anatomy & histology , Lonicera/physiology , Plant Nectar , Pollen/physiology , PollinationABSTRACT
The genus Lonicera (Caprifoliaceae) is of great economical significance. It has been taxonomically studied frequently in history, while phylogenetic relationships intra the genus are still obscure. Here, we reported the first species complete chloroplast genome sequence in the section Isoxylosteum, Lonicera angustifolia var. myrtillus. It is 156,222 bp in length, comprising a large single-copy (LSC) region of 89,838 bp, a small single-copy (SSC) region of 19,211 bp, and a pair of inverted repeats (IRs) of 23,509 bp. In L. angustifolia var. myrtillus chloroplast genome, a total of 114 functional genes were identified, with an overall GC content of 38.4%. The phylogenetic relationships of Lonicera based on maximum-likelihood (ML) showed that L. angustifolia var. myrtillus is most closely related to L. nervosa in section Isika. Our study contributes to the molecular phylogenetic studies of Lonicera and Caprifoliaceae.
ABSTRACT
Lonicera oblata, a critically endangered species endemic to North China with about 30 wild individuals, has long been ignored for conservation since its publication because of little attention on its living situation. In this study, we characterized the complete chloroplast (cp) genome of L. oblata. The cp genome was 155,481 bp in length, included a large single-copy (LSC) region of 89,139 bp, a small single-copy (SSC) region of 18,676 bp, and two inverted repeat (IR) regions of 23,833 bp each. The genome contains 130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic position of L. oblata was also investigated based on cp genome phylogeny of Lonicera representatives. This study is valuable for molecular phylogenetic study and conservation of Lonicera and related taxa.
ABSTRACT
Symphoricarpos orbiculatus is an important landscape and ornamental plant. In this study, we report the complete chloroplast genome sequences of S. orbiculatus. The complete chloroplast genome of S. orbiculatus was 156,044 bp in length. The genome has a typical quadripartite structure, including a large single-copy (LSC) region of 88,756 bp, a small single-copy (SSC) region of 19,130 bp, and two inverted repeat (IR) regions of 24,079 bp each. Overall, the GC content was 38.4%. In the genome, it was identified to comprise130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. This study provides valuable information for molecular phylogenetic study of Caprifoliaceae and is significant for variety development of Symphoricarpos.
