Paulownia species are important ecological, economic and ornamental species, but their phylogenetic relationship remains unclear, which seriously affects the development and utilization of these important resources. The complete chloroplast genomes of six Paulownia species were assembled by next-generation sequencing data. By adding two known Paulownia chloroplast genomes to these six assembled genomes, we performed the comparative analysis and phylogenetic tree reconstruction of Paulownia. The results indicated that the chloroplast genomes of Paulownia species ranged in size from 154,107 to 154,694 bp. These chloroplast genomes contained 117 unique functional genes, including 80 protein-coding genes, four rRNA genes, and 33 tRNA genes. Twelve hotspot regions, five protein-coding genes and seven noncoding regions, were identified in the chloroplast genomes that showed high levels of sequence variation. Additionally, positive selection was observed in three genes, rps2, rbcL and ndhG. The maximum likelihood (ML) and Bayesian (BI) analysis strongly supported the monophyletic origin of Paulownia species, which clustered into two major clades: One clade included P. coreana, P. tomentosa and P. kawakamii, while the other clade comprised the 5 other species including P. fargesii and P. australis. This study provides useful genetic information for phylogenetic reconstruction, taxonomic discrepancies, and studying species evolution and phylogeography in Paulownia.

The plastid genomes (plastomes) of angiosperms are typically highly conserved, with extreme reconfiguration being uncommon, although reports of such events have emerged in some lineages. In this study, we conducted a comprehensive comparison of the complete plastomes from twenty-two species, covering seventeen genera from three subfamilies (Fumarioideae, Hypecooideae, and Papaveroideae) of Papaveraceae. Our results revealed a high level of variability in the plastid genome size of Papaveraceae, ranging from 151,864 bp to 219,144 bp in length, which might be triggered by the expansion of the IR region and a large number of repeat sequences. Moreover, we detected numerous large-scale rearrangements, primarily occurring in the plastomes of Fumarioideae and Hypecooideae. Frequent gene loss or pseudogenization were also observed for ndhs, accD, clpP, infA, rpl2, rpl20, rpl32, rps16, and several tRNA genes, particularly in Fumarioideae and Hypecooideae, which might be associated with the structural variation in their plastomes. Furthermore, we found that the plastomes of Fumarioideae exhibited a higher GC content and more repeat sequences than those of Papaveroideae. Our results showed that Papaveroideae generally displayed a relatively conserved plastome, with the exception of Eomecon chionantha, while Fumarioideae and Hypecooideae typically harbored highly reconfigurable plastomes, showing high variability in the genome size, gene content, and gene order. This study provides insights into the plastome evolution of Papaveraceae and may contribute to the development of effective molecular markers.

Styphnolobium japonicum is a significant resource of ornamental and medicinal plants. In this study, we employed high-throughput sequencing to assemble nine chloroplast genomes of S. japonicum. We compared and reconstructed the phylogenetic relationships of these genomes, along with three publicly available chloroplast genomes. Our results showed that the length of the 12 S. japonicum chloroplast genomes ranged from 158,613 bp to 158,837 bp, all containing 129 unique functional genes. The genetic diversity within S. japonicum chloroplast genomes was relatively low, with π = 0.00029, Theta-W = 0.00028, and an indel frequency of 0.62 indels/1 kb. Among the four regions, the SSC region exhibited the highest genetic diversity and indel frequency, while the IR region had the lowest. Non-coding regions displayed greater genetic variation compared to coding regions, with a few highly variable regions identified. The phylogenetic tree constructed revealed that the major cultivars of S. japonicum originated from two genetic ‘sources. S. japonicum ‘JinhuaiJ2’ had an independent origin and showed close relatedness to S. japonicum var. violacea, S. japonicum var. japonicum, and S. japonicum f. oligophylla. On the other hand, other major cultivars shared a common genetic origin and were closely related to S. japonicum f. pendula. This study highlights the variability of chloroplast genomes within S. japonicum and provides insights into the genetic origins of major cultivars and their relationships with different varieties and forma.

Premise of the study: Phytolacca acinosa (Phytolaccaceae) is a traditional Chinese herb with multiple medicinal uses and is an important pigment source. Due to excessive human harvesting, the population numbers and sizes have decreased dramatically.Methods and Results: Using an enriched genomic library, we developed and characterized 15 microsatellite primers for P. acinosa, 13 of which were polymorphic. The number of alleles varied from two to seven. The observed heterozygosity and expected heterozygosity per locus ranged from 0.267 to 1.000 and 0.331 to 0.743, respectively. All of the primers that were developed were also successfully applied in P. americana.Conclusions: These markers should be useful in probing the genetic diversity, genetic structure, and mating systems of P. acinosa, which could provide information about protecting and sustainably harvesting this species.

Iris lactea var. chinensis is a well-regarded ornamental plant in the genus Iris (family Iridaceae). In this report, we present the complete chloroplast (cp) genome sequence of I. lactea var. chinensis for the first time. The complete cp genome of I. lactea var. chinensis was assembled using high-throughput sequencing, and phylogenetic analysis was undertaken based on a dataset of coding regions. The cp genome of I. lactea var. chinensis measures 152,409 bp in length, with regions having two inverted copies (IR 26,026 bp), and separated by the large single copy (LSC 82,256 bp) and small single copy (SSC 18,101 bp) regions. The cp genome encodes 133 unique genes, including 87 different protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Based on a dataset of 69 chloroplast coding regions, the maximum-likelihood (ML) phylogenetic tree analysis indicated that Iris lactea var. chinensis clusters closely with Iris sanguinea. Thus, the complete chloroplast genome presented in this report may provide valuable genetic information not only for the future exploitation and utilization of this plant resource but also for further research investigating its relationship with other Iris species.

Corydalis DC. is the largest and most diverse genus of Papaveraceae, which has undergone rapid diversification. Corydalis is notable for its diverse benzylisoquinoline alkaloids (BIAs). However, limited genomic resources hinder the understanding of its evolution and BIA diversity. Here, we report a high-quality genome of Corydalis sheareri and provide a comparative analysis of Corydalis genomes. Genome survey shows that the genome of C. sheareri might be an autotetraploid. De novo assembly yields a single homolog genome of 282 Mb, with a contig N50 of 11.39 Mb. Repetitive DNA accounts for 44.47% of the genome, and a total of 26,287 protein-coding genes are predicted. When comparing this genome with the previously reported diploid genome of C. tomentella, large-scale structural variations are detected, which might have dramatic effects on the evolution of Corydalis. Furthermore, a total of 172 candidate genes involved in benzylisoquinoline alkaloids (BIAs) biosynthesis are identified in the genome of C. sheareri. Duplication and phylogenetic analyses indicate that tandem duplications play a prominent role in the evolution of the BIA biosynthesis genes, and might be associated with the BIA diversity in Corydalis.Our study provides more insights into the genome evolution and secondary metabolites diversity of Corydalis, and will accelerate genomic and evolutionary radiation study of species-rich plant genera.