Insights into cryptic speciation of quillworts in China

Cryptic species are commonly misidentified because of high morphological similarities to other species.One group of plants that may harbor large numbers of cryptic species is the quillworts(Isoetes spp.),an ancient aquatic plant lineage.Although over 350 species of Isoetes have been reported globally,only ten species have been recorded in China.The aim of this study is to better understand Isoetes species diversity in China.For this purpose,we systematically explored the phylogeny and evolution of Isoetes using complete chloroplast genome(plastome)data,spore morphology,chromosome number,genetic structure,and haplotypes of almost all Chinese Isoetes populations.We identified three ploidy levels of Isoetes in Chinaddiploid(2n=22),tetraploid(2n=44),and hexaploid(2n=66).We also found four megaspore and microspore ornamentation types in diploids,six in tetraploids,and three in hexaploids.Phylogenetic analyses confirmed that I.hypsophila as the ancestral group of the genus and revealed that Isoetes diploids,tetraploids,and hexaploids do not form monophyletic clades.Most individual species possess a single genetic structure;however,several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data.All 36 samples shared 22 haplotypes.Divergence time analysis showed that I.hypsophila diverged in the early Eocene(~48.05 Ma),and most other Isoetes species diverged 3-20 Ma.Additionally,different species of Isoetes were found to inhabit different water systems and environments along the Yangtze River.These findings provide new insights into the relationships among Isoetes species in China,where highly similar morphologic populations may harbor many cryptic species.

Astragalus polysaccharide attenuates rat experimental colitis by inducing regulatory T cells in intestinal Peyer's patches

AIM: To explore probable mechanism underlying the therapeutic effect of Astragalus polysaccharide(APS) against experimental colitis.METHODS: Thirty-two Sprague-Dawley rats were randomly divided into four groups. Colitis was induced with 2, 4, 6-trinitrobenzene sulfonic acid(TNBS). The rats with colitis were treated with 400 mg/kg of APS for 7 d. The therapeutic effect was evaluated by colonic weight, weight index of the colon, colonic length, and macroscopic and histological scores. The levels of regulatory T(Treg) cells in Peyer's patches were measured by flow cytometry, and cytokines in colonic tissue homogenates were analyzed using enzyme-linked immunosorbent assay. The expression of related orphan receptor-gt(ROR-gt), IL-23 and STAT-5a was measured by Western blot.RESULTS: After 7-d treatment with APS, the weight index of the colon, colonic weight, macroscopical and histological scores were decreased, while the colonic length was increased compared with the model group. The expression of interleukin(IL)-2, IL-6, IL-17, IL-23 and ROR-gt in the colonic tissues was down-regulated, but Treg cells in Peyer's patches, TGF-β and STAT5 a in the colonic tissues were up-regulated.CONCLUSION: APS effectively ameliorates TNBSinduced experimental colitis in rats, probably through restoring the number of Treg cells, and inhibiting IL-17 levels in Peyer's patches.