Comparative genomics and phylogenetic analysis of chloroplast genomes of Asian Caryodaphnopsis taxa (Lauraceae).

The genus Caryodaphnopsis, a member of the Lauraceae family, is characterized by seeds that are rich in oil, as well as highly exploitable fruits and wood. The Asian taxa within this genus exhibit complex morphological variations, posing challenges to their accurate classification and impeding their effective use and development as a resource. In this study, we sequenced the chloroplast genomes of 31 individuals representing nine Asian taxa within the Caryodaphnopsis genus. Our primary objectives were to reveal structural variations in these chloroplast genomes through comparative analyses and to infer the species' phylogenetic relationships. Our findings revealed that all chloroplast genomes had a tetrad structure, ranged in length from 148,828 to 154,946 bp, and harbored 128-131 genes. Notably, contraction of the IR region led to the absence of some genes in eight taxa. A comprehensive analysis identified 1267 long repetitive sequences and 2176 SSRs, 286 SNPs, and 135 indels across the 31 chloroplast genomes. The Ka/Ks ratio analysis indicated potential positive selection on the matK, rpl22, and rpoC2 genes. Furthermore, we identified six variable regions as promising barcode regions. Phylogenetic analysis grouped the nine Asian taxa into six branches, with C. henryi forming the basal group from which three distinct complexes emerged. This study contributes significantly to the current understanding of the evolutionary dynamics and phylogenetic relationships within the genus Caryodaphnopsis. Furthermore, the identified molecular markers hold potential for molecular barcoding applications in population genetics, providing valuable tools for future research and conservation efforts within this diverse genus.

The complete chloroplast genome of Bauhinia racemosa Lam. (Fabaceae): a versatile tropical medicinal plant.

Bauhinia racemosa Lam. (1783), a versatile medicinal plant, belongs to the family Fabaceae (subfamily Cercidoideae). In this study, we analyzed the complete chloroplast genome to facilitate its use in genetic research. The complete chloroplast genome of B. racemosa was found to be 155,501 bp long, including two inverted repeat (IR) regions of 25,446 bp, which are separated by a small single-copy (SSC) region of 18,295 bp and a large single-copy (LSC) region of 86,314 bp. The overall GC content is 36.4%. The genome of B. racemosa contains 129 genes, including 83 protein-coding genes, 37 tRNAs, 8 rRNAs, and 1 pseudogene (rps19). Phylogenetic analysis suggests that B. racemosa forms a monophyletic clade with the other four Bauhinia species (B. brachycarpa, B. purpurea, B. blakeana and B. variegata var. variegata).

Trade-offs between xylem hydraulic efficiency and mechanical strength in Chinese evergreen and deciduous savanna species.

Evergreen and deciduous species coexist in tropical dry forests and savannas, but differ in physiological mechanisms and life-history strategies. Hydraulic conductivity and mechanical support are two major functions of the xylems of woody plant species related to plant growth and survival. In this study, we measured sapwood-specific hydraulic conductivity (Ks), leaf-specific hydraulic conductivity (KL), modulus of rupture (MOR) and elasticity (MOE), xylem anatomical traits and fiber contents in the xylems of 20 woody species with contrasting leaf phenology (evergreen vs deciduous) in a Chinese savanna. Our results showed that deciduous species had significantly higher Ks and KL but lower MOR and MOE than evergreen species. Evergreen species experienced more negative seasonal minimum water potential (Pmin) than deciduous species during the dry season. Furthermore, we found trade-offs between xylem hydraulic efficiency and mechanical strength across species and within the evergreen and deciduous groups, and these trade-offs were modulated by structural and chemical traits. Both Ks and KL were significantly related to hydraulic weighted vessel diameter (Dh) across all species and within the deciduous group. Both MOR and MOE were significantly related to wood density, neutral detergent fiber and acid detergent fiber across species and within evergreen and deciduous groups. Our findings demonstrated that Chinese evergreen and deciduous savanna species diverged in xylem hydraulic and mechanical functions, reflecting conservative and acquisitive life-history strategies for evergreen and deciduous species, respectively. This study provides new information with which to understand the hydraulic and biomechanical properties and ecological strategies of savanna species in long-term dry-hot environments.

The complete plastome sequence of Illigera grandiflora.

Illigera grandiflora, a kind of traditional medicinal liana, belongs to the Illigera Blume of the Hernandiaceae. In this study, we reported the characteristics of complete plastome for I. grandiflora. Its total plastome was 156,138 bp in length, comprising a large single-copy region(LSC) of 84,931 bp, a small single-copy region (SSC) of 18,544 bp, and a pair of inverted repeat (IR) regions of 26,549 bp. The overall GC content was 39.16% (LSC, 37.77%; SSC, 33.89%; IR, 43.21%). The plastome encoded 134 genes, including 83 protein-coding genes, 42 transfer RNA genes, and 10 ribosomal RNA genes. The relationships in our phylogeny showed that the two Illigera species are located in the same clade, with Hernandia nymphaeifolia being the next sister group, followed by Wilkiea huegeliana.

The complete chloroplast genome sequence of Illigera celebica.

Illigera celebica is an evergreen woody vine that belongs to genus Illigera Bl in the family Hernandiaceae and has medicinal value. The complete chloroplast genome of I. celebica was sequenced to determine its phylogenetic location with respect to the other species under the Laurales. Its whole chloroplast genome is 156,123 bp in length, and comprises a large single-copy region (LSC, 84,913 bp), a small single-copy region (SSC,18,775 bp), and a pair of inverted repeats (IRs, 26,217 bp). The overall GC content is 39.2% (LSC, 37.8%; SSC, 33.9%; IR, 43.4%). Maximum likelihood phylogenetic analysise (TVM + F + R2 model) was conducted using 15 complete chloroplast genomes of Laurales, and the results confirmed that Hernandia nymphaeifolia and Wilkiea huegeliana were located in the same lineage.