Gynostemma BL., belonging to the family Cucurbitaceae, is a genus containing 17 creeping herbaceous species mainly distributed in East Asia. It can be divided into two subgenera based on different fruit morphology. Herein, we report eight complete chloroplast genome sequences of the genus Gynostemma, which were obtained by Illumina paired-end sequencing, assembly, and annotation. The length of the eight complete cp genomes ranged from 157,576 bp (G. pentaphyllum) to 158,273 bp (G. laxiflorum). Each encoded 133 genes, including 87 protein-coding genes, 37 tRNA genes, eight rRNA genes, and one pseudogene. The four types of repeated sequences had been discovered and indicated that the repeated structure for species in the Subgen. Triostellum was greater than that for species in the Subgen. Gynostemma. The percentage of variation of the eight cp genomes in different regions were calculated, which demonstrated that the coding and inverted repeats regions were highly conserved. Phylogenetic analysis based on Bayesian inference and maximum likelihood methods strongly supported the phylogenetic position of the genus Gynostemma as a member of family Cucurbitaceae. The phylogenetic relationships among the eight species were clearly resolved using the complete cp genome sequences in this study. It will also provide potential molecular markers and candidate DNA barcodes for future studies and enrich the valuable complete cp genome resources of Cucurbitaceae.

Dipteronia (order Sapindales) is an endangered genus endemic to China and has two living species, D.sinensis and D. dyeriana. The plants are closely related to the genus Acer, which is also classified in the order Sapindales. Evolutionary studies on Dipteronia have been hindered by the paucity of information on their genomes and plastids. Here, we used next generation sequencing to characterize the transcriptomes and complete chloroplast genomes of both Dipteronia species. A comparison of the transcriptomes of both species identified a total of 7814 orthologs. Estimation of selection pressures using Ka/Ks ratios showed that only 30 of 5435 orthologous pairs had a ratio significantly >1, i.e., showing positive selection. However, 4041 orthologs had a Ka/Ks < 0.5 (p < 0.05), suggesting that most genes had likely undergone purifying selection. Based on orthologous unigenes, 314 single copy nuclear genes (SCNGs) were identified. Through a combination of de novo and reference guided assembly, plastid genomes were obtained; that of D. sinensis was 157,080 bp and that of D. dyeriana was 157,071 bp. Both plastid genomes encoded 87 protein coding genes, 40 tRNAs, and 8 rRNAs; no significant differences were detected in the size, gene content, and organization of the two plastomes. We used the whole chloroplast genomes to determine the phylogeny of D. sinensis and D. dyeriana and confirmed that the two species were highly divergent. Overall, our study provides comprehensive transcriptomic and chloroplast genomic resources, which will be valuable for future evolutionary studies of Dipteronia.

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