Distributions, ex situ conservation priorities, and genetic resource potential of crop wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas]

Crop wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas] have the potential to contribute to breeding objectives for this important root crop. Uncertainty in regard to species boundaries and their phylogenetic relationships, the limited availability of germplasm with which to perform crosses, and the difficulty of introgression of genes from wild species has constrained their utilization. Here, we compile geographic occurrence data on relevant sweetpotato wild relatives and produce potential distribution models for the species. We then assess the comprehensiveness of ex situ germplasm collections, contextualize these results with research and breeding priorities, and use ecogeographic information to identify species with the potential to contribute desirable agronomic traits. The fourteen species that are considered the closest wild relatives of sweetpotato generally occur from the central United States to Argentina, with richness concentrated in Mesoamerica and in the extreme Southeastern United States. Currently designated species differ among themselves and in comparison to the crop in their adaptations to temperature, precipitation, and edaphic characteristics and most species also show considerable intraspecific variation. With 79% of species identified as high priority for further collecting, we find that these crop genetic resources are highly under-represented in ex situ conservation systems and thus their availability to breeders and researchers is inadequate. We prioritize taxa and specific geographic locations for further collecting in order to improve the completeness of germplasm collections. In concert with enhanced conservation of sweetpotato wild relatives, further taxonomic research, characterization and evaluation of germplasm, and improving the techniques to overcome barriers to introgression with wild species are needed in order to mobilize these genetic resources for crop breeding

Discovery and characterization of sweetpotato’s closest tetraploid

The origin of sweetpotato, a hexaploid species, is poorly understood, partly because the identity of its tetraploid progenitor remains unknown. In this study, we identify, describe and characterize a new species of Ipomoea that is sweetpotato's closest tetraploid relative known to date and probably a direct descendant of its tetraploid progenitor. We integrate morphological, phylogenetic, and genomic analyses of herbarium and germplasm accessions of the hexaploid sweetpotato, its closest known diploid relative Ipomoea trifida, and various tetraploid plants closely related to them from across the American continent. We identify wild autotetraploid plants from Ecuador that are morphologically distinct from Ipomoea batatas and I. trifida, but monophyletic and sister to I. batatas in phylogenetic analysis of nuclear data. We describe this new species as Ipomoea aequatoriensis T. Wells & P. Munoz sp. nov., distinguish it from hybrid tetraploid material collected in Mexico; and show that it likely played a direct role in the origin of sweetpotato's hexaploid genome. This discovery transforms our understanding of sweetpotato's origin

Richness and distribution of salvia subg. Calosphace (lamiaceae)

Premise of research. Salvia is one of the most species-rich genera in the world. Its outstanding diversity and subcosmopolitan distribution have prevented the preparation of a modern comprehensive monograph and re-evaluation of its classification. As phylogenetic efforts advance to untangle the evolutionary relationships of Salvia, the need for a solid taxonomic footing is increasingly imperative. Accordingly, we present an updated checklist of the species richness and distribution of Salvia subg. Calosphace, which constitutes more than half of the diversity of the genus. Methodology. A preliminary checklist of the species of Salvia subg. Calosphace was compiled through examination of the literature and online databases; this was revised and discussed by the authors in order to retrieve a consensus list. The distribution of each species by country or territory as well as by biome was also recorded from the sources consulted; affinities in composition were visualized with the unweighted pair group method with arithmetic mean based on a dissimilarity matrix (Sørensen’s index). Pivotal results. Salvia subg. Calosphace comprises 580 species; 30 were qualified as unresolved and require further analysis. The countries with the highest species richness are Mexico (295 spp.), Peru (77 spp.), Colombia (60 spp.), Brazil (58 spp.), Guatemala (49 spp.), and Ecuador (41 spp.). The affinity in species composition between countries and between biomes is explained mainly by geographical proximity. Conclusions. The updated list of the species of Salvia subg. Calosphace will help to guide sampling for phylogenetic analyses, enabling the achievement of a more stable and solid phylogenetic hypothesis. At the same time, it is a potentially important tool for underpinning discussions toward a new sectional classification of the lineage

A taxonomic monograph of Ipomoea integrated across phylogenetic scales.

Taxonomic monographs have the potential to make a unique contribution to the understanding of global biodiversity. However, such studies, now rare, are often considered too daunting to undertake within a realistic time frame, especially as the world’s collections have doubled in size in recent times. Here, we report a global-scale monographic study of morning glories (Ipomoea) that integrated DNA barcodes and high-throughput sequencing with the morphological study of herbarium specimens. Our approach overhauled the taxonomy of this megadiverse group, described 63 new species and uncovered significant increases in net diversification rates comparable to the most iconic evolutionary radiations in the plant kingdom. Finally, we show that more than 60 species of Ipomoea, including sweet potato, independently evolved storage roots in pre-human times, indicating that the storage root is not solely a product of human domestication but a trait that predisposed the species for cultivation. This study demonstrates how the world’s natural history collections can contribute to global challenges in the Anthropocene