A taxonomic study of twelve wild forage species of Fabaceae

Deciphering the Plastomic Code of Chinese Hog-Peanut (Amphicarpaea edgeworthii Benth., Leguminosae): Comparative Genomics and Evolutionary Insights within the Phaseoleae Tribe

The classification and phylogenetic relationships within the Phaseoleae tribe (Leguminosae) have consistently posed challenges to botanists. This study addresses these taxonomic intricacies, with a specific focus on the Glycininae subtribe, by conducting a comprehensive analysis of the highly conserved plastome in Amphicarpaea edgeworthii Benth., a critical species within this subtribe. Through meticulous genomic sequencing, we identified a plastome size of 148,650 bp, composed of 128 genes, including 84 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Comparative genomic analysis across seven Glycininae species illuminated a universally conserved circular and quadripartite structure, with nine genes exhibiting notable nucleotide diversity, signifying a remarkable genomic variability. Phylogenetic reconstruction of 35 Phaseoleae species underscores the affinity of Amphicarpaea with Glycine, placing Apios as a sister lineage to all other Phaseoleae species, excluding Clitorinae and Diocleinae subtribes. Intriguingly, Apios, Butea, Erythrina, and Spatholobus, traditionally clumped together in the Erythrininae subtribe, display paraphyletic divergence, thereby contesting their taxonomic coherence. The pronounced structural differences in the quadripartite boundary genes among taxa with unresolved subtribal affiliations demand a reevaluation of Erythrininae's taxonomic classification, potentially refining the phylogenetic contours of the tribe.

Chromosome-scale genomes of five Hongmu species in Leguminosae

The Legume family (Leguminosae or Fabaceae), is one of the largest and economically important flowering plants. Heartwood, the core of a tree trunk or branch, is a valuable and renewable resource employed for centuries in constructing sturdy and sustainable structures. Hongmu refers to a category of precious timber trees in China, encompassing 29 woody species, primarily from the legume genus. Due to the lack of genome data, detailed studies on their economic and ecological importance are limited. Therefore, this study generates chromosome-scale assemblies of five Hongmu species in Leguminosae: Pterocarpus santalinus, Pterocarpus macrocarpus, Dalbergia cochinchinensis, Dalbergia cultrata, and Senna siamea, using a combination of short-reads, long-read nanopore, and Hi-C data. We obtained 623.86 Mb, 634.58 Mb, 700.60 Mb, 645.98 Mb, and 437.29 Mb of pseudochromosome level assemblies with the scaffold N50 lengths of 63.1 Mb, 63.7 Mb, 70.4 Mb, 61.1 Mb and 32.2 Mb for P. santalinus, P. macrocarpus, D. cochinchinensis, D. cultrata and S. siamea, respectively. These genome data will serve as a valuable resource for studying crucial traits, like wood quality, disease resistance, and environmental adaptation in Hongmu.

Numerical analyses of seed morphology and its taxonomic significance in the genus Oxytropis DC. (Fabaceae) from northwestern China

The lack of diagnostic taxonomic characteristics in some species complexes leave the species delimitation of Oxytropis DC. unresolved. Seed morphological features have proved to be useful diagnostic and taxonomic characteristics in Fabaceae. However, there are few systematic studies on the seed characteristics of Oxytropis. Here, we used scanning electron and stereoscopic microscopy to investigate the seed characteristics of 35 samples obtained from 21 Oxytropis species from northwest China. Our examination showed two main types of hilum positions, terminal and central, and five different types of seed shapes: prolonged semielliptic, reniform, prolonged reniform, quadratic, and cardiform. Seven different sculpturing patterns were identified: scaled, regulated, lophate with stellated testa cells, simple reticulate, rough, compound reticulate, and lophate with rounded testa cells. The seeds ranged from 1.27 to 2.57 mm in length and from 1.18 to 2.02 mm in width, and the length-to-width ratio ranged from 0.89 to 1.55 mm. The seed shape was constant within species and was useful for species delimitation within the genus Oxytropis when combined with other macroscopic traits. In contrast, the sculpturing patterns were highly variable at the species level and could not be used for species identification. Results of the cluster analysis and principal component analysis (PCA) indicated that the seed traits of Oxytropis species are useful for taxa identification at the species level, but have low taxonomic value at the section level.