The genus Poa comprises approximately 500 species that occur throughout the world, including the widely grown Kentucky bluegrass (P. pratensis L.). Hybridization and polyploidization have played a prominent role in the evolution of this complex genus, but limited information is available regarding genome relationships in Poa. Thus, we amplified, cloned, and compared the DNA sequences of 2 nuclear genes (CDO504 and thioredoxin-like protein) and 2 chloroplast genome loci (ndhF and trnT-trnF) from 22 Poa species. Four distinct classes of sequences corresponding to 4 putative homoeologous loci from each nuclear gene were found within polyploid P. pratensis. Nuclear sequences from 15 other Poa species were found to group with at least 1 P. pratensis homoeolog, whereas 6 species displayed sequences not present in P. pratensis. The nuclear genome phylogenies presented here show the first evidence of diverse and related genomes in the genus Poa.

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Greater ABL was associated with higher ACPA, consistent with findings at articular sites. ACPA targeting could provide novel insight into important linkages between RA and periodontitis.

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BackgroundKentucky bluegrass (Poa pratensis L.) is a prominent turfgrass in the cool-season regions, but it is sensitive to salt stress. Previously, a relatively salt tolerant Kentucky bluegrass accession was identified that maintained green colour under consistent salt applications. In this study, a transcriptome study between the tolerant (PI 372742) accession and a salt susceptible (PI 368233) accession was conducted, under control and salt treatments, and in shoot and root tissues.ResultsSample replicates grouped tightly by tissue and treatment, and fewer differentially expressed transcripts were detected in the tolerant PI 372742 samples compared to the susceptible PI 368233 samples, and in root tissues compared to shoot tissues. A de novo assembly resulted in 388,764 transcripts, with 36,587 detected as differentially expressed. Approximately 75 % of transcripts had homology based annotations, with several differences in GO terms enriched between the PI 368233 and PI 372742 samples. Gene expression profiling identified salt-responsive gene families that were consistently down-regulated in PI 372742 and unlikely to contribute to salt tolerance in Kentucky bluegrass. Gene expression profiling also identified sets of transcripts relating to transcription factors, ion and water transport genes, and oxidation-reduction process genes with likely roles in salt tolerance.ConclusionsThe transcript assembly represents the first such assembly in the highly polyploidy, facultative apomictic Kentucky bluegrass. The transcripts identified provide genetic information on how this plant responds to and tolerates salt stress in both shoot and root tissues, and can be used for further genetic testing and introgression.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2379-x) contains supplementary material, which is available to authorized users.

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Poa is a complex genus taxonomically and genetically. As a result, relatively little information exists for this economically important genus with regards to reproductive mode and variability in chromosome number. We examined apomixis frequency and ploidy levels in 83 Poa accessions representing 33 species from the National Plant Germplasm System using flow cytometric techniques. In reproductive mode analysis, we analyzed at least three preparations of 50 seeds each from the accessions. In ploidy level analysis, at least three plants of each accession were analyzed. Sixty percent of the species had at least one apomictic or facultative apomictic accession; 40% were sexual. Thirty‐three percent of the species had no sexual accessions. Autonomous apomixis was newly identified in P. bactriana and P. bulbosa in addition to it being previously reported in P. nervosa. Poa annua and P. trivialis were identified as obligate sexual, and P. nervosa as obligate apomictic. Two of four P. palustris accessions exhibited facultative apomixis. Ploidy levels among sexually reproducing Poa accessions ranged from 2n = 2x = 14 to 2n = 12x = 84, with most accessions between 2n = 3x = 21 to 2n = 8x = 56. Among apomictic accessions, ploidy levels ranged from 2n = 3x = 21 to 2n = 10x = 70, with most between 2n = 4x = 28 and 2n = 10x = 70. These results emphasize the wide variability in Poa, both among and within species.