Phylogenetic relationships among low-ploidy species ofPoausing chloroplast sequences

Abstract

Species of the genus Poa are taxonomically and genetically difficult to delineate owing to high and variable polyploidy, aneuploidy, and challenging breeding systems. Approximately 5% of the proposed species in Poa are considered to include or comprise diploids, but very few of those diploids are represented in seed collections. Recent phylogenetic studies of Poa have included some diploid species to elucidate Poa genome relationships. In this study, we build upon that foundation of diploid Poa relationships with additional confirmed diploid species and accessions, and with additional chloroplast sequences. We also include samples of P. pratensis and P. arachnifera to hone in on possible ancestral genomes in these two agronomic and highly polyploidy species. Relative to most species of Poa, Poa section Dioicopoa (P. ligularis, P. iridifolia, and P. arachnifera) contained relatively large chromosomes. Phylogenies were constructed using the TLF gene region and five additional chloroplast genes, and the placement of new species and accessions fit within chloroplast lineages previously reported better than by taxonomic subgenera and sections. Low-ploidy species in the P chloroplast lineage, such as P. iberica and P. remota, grouped closest to P. pratensis.

Long-term survival and successful conservation? Low genetic diversity but no evidence for reduced reproductive success at the north-westernmost range edge of Poa badensis (Poaceae) in Central Europe

“…P . badensis is predominantly described as a diploid species (Müntzing and Nygren 1955 ; Joshi et al 2017 ). Nevertheless, the following chromosome numbers have been reported without precise information about the geographical origin: 2n = 14, 28, 42 (Oberdorfer 2001 ) and 2n = 14, 18, 21, 28 (Conert 2000 ; including odd numbers).…”

Poa jubata (Poaceae), a rare Balkan species, first record for the Italian flora

“…As far as karyology is concerned, Poa jubata shows a diploid chromosome complement with 2n = 14, not common among Poa species, which are usually high and variably polyploid (Joshi et al 2017). Actually, this diploid complement seems shared by only a few species, such as P. infirma, also annual, as well as the perennial P. supina Schrad.…”

Molecular Markers Improve Breeding Efficiency in Apomictic Poa Pratensis L.

“…Chromosome staining and counting were done as per Joshi et al [17]: briefly, healthy root tips were collected 2-3 h after sunrise and fixed in cold 2 mM 8-hydroxyquinoline for 4 h. Samples were then transferred to an aceto-orcein solution for 48 h, squashed on a glass slide containing 1 drop of 45% acetic acid, and examined under a light microscope at 1000× resolution.…”

“…Eventually, these sequence libraries will provide sufficient information to allow development of validated molecular markers for high-quality genotyping in Kentucky bluegrass breeding. Additionally, sequencing within related Poa species has provided an ability to re-examine lower ploidy Poa genomes similar to Kentucky bluegrass [17], possibly pinpointing ancestral diploid Poa genomes present in P. pratensis and allowing breeders to determine which genome(s) provide value added characteristics.…”