Trapa L., an annual floating-leaved herb, is widely distributed in the old world and has important edible and medicinal values. However, the taxonomy and phylogeny of Trapa are unclear. Here, we reported the complete chloroplast genome of a wild species with small nuts, T. incisa. The complete chloroplast genome size of T. incisa was 155, 453 bp, consisting of two inverted repeat (IR) regions (24, 388 bp), one large single copy (LSC) region (88, 398 bp) and one small single copy (SSC) region (18, 279 bp). A total of 129 genes were annotated, including 83 protein-coding genes, 38 tRNA genes and 8 rRNA genes. Among them, 19 genes were duplicated (6 protein-coding genes, 9 tRNA genes and 4 rRNA genes). The phylogenomic analysis suggested a close relationship between T. incisa and T. maximowiczii.

Trapa (Lythraceae) is an economically important aquatic genus used for food and medicine, with wide distribution in Asia, Africa, and Europe. Identification of species, genetic studies and utilization of Trapa are limited by lack of molecular data. Herein, we report the complete chloroplast (cp) genome sequence of a wild species, Trapa kozhevnikoviorum Pshenn. The cp genome size of T. kozhevnikoviorum is 155,545 bp, consisting of a pair of inverted repeat regions (IRa/IRb) of length 24,388 bp, separated by the small single copy (SSC) region of 18,275 bp and a large single copy (LSC) region of 88,494 bp. A total of 113 unique genes, including 79 protein-coding, 30 tRNA, and four rRNA were annotated. Phylogenetic analysis based on 15 whole cp genomes of Lythraceae species supported the monophyletic clustering of Trapa. A cladal relationship among T. kozhevnikoviorum, T. bicornis, and T. natans was revealed.

Myricaria wardii Marquand 1929, endemic to the Tibet Plateau, is a perennial shrub with important medicinal and ecological values. In this study, the complete chloroplast (cp) genome of M. wardii was assembled, and the phylogenetic tree was reconstructed to evaluate the phylogenetic location of the species. The results showed that the cp genome size of the M. wardii was 155,299 bp, which contained a pair of inverted repeat (IR) regions (26,150 bp), a large single copy (LSC) region (84,715 bp), and a small single copy (SSC) region (18,284 bp). The total GC content of the cp genome was 36.30%. A total of 128 genes were annotated, consisting of 83 protein-coding genes, 37 tRNA genes and 8 rRNA genes. The phylogenetic analysis showed that M. wardii was closely related to M. prostrata. This study provides useful information for the conservation of this species and the phylogenetic analysis of Tamaricaceae.

Trapa L. is floating-leaved aquatic plants with important economic and ecological values. However, species identification and phylogenetic relationship are still unresolved for Trapa . In this study, complete chloroplast genomes of 13 Trapa species/taxa were sequenced and annotated. Combined with released sequences of the other two species, comparative analysis of cp genomes was first performed on the 15 Trapa species/taxa. The 15 cp genomes exhibited quadripartite structures with medium size of 155, 453-155, 559 bp. IR/SC junctions were conservative with no obvious change found. Long repetitive repeats and SSRs were mostly detected in the intergenic and LSC regions, providing useful plastid markers for species and relationship identification. Three phylogenetic analyses (MP, ML and BI) consistently showed two clusters within Trapa , including large- and small-seed species/taxa, respectively. This study provided the baseline information for phylogeography of Trapa , which would facilitate the management and utilization of genetic resources of the genus.

Submerged macrophyte and periphyton are main primary producers which strongly interact with each other in clear water shallow lakes. In this study, the effects of genetic variation of the macrophyte species on periphyton biomass were studied in five submerged species. A two-year mesocosm study was conducted with four levels of genetic diversity (1, 4, 8 and 16 genotypes) for each submerged macrophyte, including 1600 individuals and 320 boxes in 20 mesocosms. Of the five submerged species, only Vallisneria spinulosa showed a positive correlation between its levels of genotype richness and the periphyton biomass. The correlation between genetic distance of genotypes and periphyton biomass was tested, which varied with the difference of seasons and species. In summary, we found that in freshwater mesocosms, the genetic diversity of submerged macrophytes may play a role in regulating the periphyton biomass, but the interaction between genetic diversity of macrophytes and periphyton biomass was not straightforward. This study will provide new insights into the interaction dynamics between the two primary producers in shallow lakes.