Saussurea talungensis (Asteraceae), a new species from Humla, Nepal Himalayas.
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ABSTRACT:
SUBMITTER: Rana HK
PROVIDER: S-EPMC8065016 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The present paper deals with meiotic studies in 15 species belonging to 6 genera of the tribe Cichorieae from various localities of Western Himalayas. The chromosome number has been reported for the first time in Hieracium crocatum (2n = 10) and Lactuca lessertiana (2n = 2x = 16). Further, intraspecific variability has been reported for the first time in H. umbellatum (2n = 2x = 10 and 2n = 6x = 54), Tragopogon dubius (2n = 2x = 14 and 2n = 4x = 28), and T. gracilis (2n = 2x = 14). The chromosome report of 2n = 2x = 10 in Youngia tenuifolia is made for the first time in India. Maximum numbers of the populations show laggards, chromosome stickiness, and cytomixis from early prophase to telophase-II, leading to the formation of aneuploid cells or meiocytes with double chromosome number. Such meiotic abnormalities produce unreduced pollen grains and the reduced pollen viability.
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Project description:BackgroundSaussurea DC. is one of the largest and most morphologically heterogeneous genera in Asteraceae. The relationships within Saussurea have been poorly resolved, probably due an early, rapid radiation. To examine plastome evolution and resolve backbone relationships within Saussurea, we sequenced the complete plastomes of 17 species representing all four subgenera.ResultsAll Saussurea plastomes shared the gene content and structure of most Asteraceae plastomes. Molecular evolutionary analysis showed most of the plastid protein-coding genes have been under purifying selection. Phylogenomic analyses of 20 Saussurea plastomes that alternatively included nucleotide or amino acid sequences of all protein-coding genes, vs. the nucleotide sequence of the entire plastome, supported the monophyly of Saussurea and identified three clades within it. Three of the four traditional subgenera were recovered as paraphyletic. Seven plastome regions were identified as containing the highest nucleotide variability.ConclusionsOur analyses reveal both the structural conservatism and power of the plastome for resolving relationships in congeneric taxa. It is very likely that differences in topology among data sets is due primarily to differences in numbers of parsimony-informative characters. Our study demonstrates that the current taxonomy of Saussurea is likely based at least partly on convergent morphological character states. Greater taxon sampling will be necessary to explore character evolution and biogeography in the genus. Our results here provide helpful insight into which loci will provide the most phylogenetic signal in Saussurea and Cardueae.
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Project description:In this study, Saussurea bogedaensis Yu-J. Wang & Jie Chen, a new species from Bogeda Mountain in the eastern part of the Tianshan Mountains, is described and discussed based on evidence in terms of both morphological and genetic data. S. bogedaensis is morphologically similar to S. involucrata, which is distributed in the western part of the Tianshan Mountains, and it is well known because of its beauty, rarity, and medicinal value. The new species is also similar to S. orgaadayi, which is distributed in the nearby Altai Mountains. Our genetic data support the close relationships among these three species. According to their allopathic distributions, we suggest that these three species are derived from the same ancestor but that they differentiated after reaching their current range. In addition, we propose that the new species might serve as an alternative to S. involucrata in medicine due to their very high similarity. However, this species appears to be rare because we only found six mature individuals in the field despite extensive investigations.
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Project description:A species in the family Asteraceae, Saussurea bogedaensis, was newly described from Bogeda Mountain in Xinjiang, China and is a critically endangered species in China. Morphological and genetic characteristics confirm the presence of this species in Mongolia, as it was found in Baitag Bogd Mountain (in the Dzungarian Gobi). In addition, the distribution and conservation status of S. bogedaensis are provided.
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Project description:PremiseNuclear microsatellite markers were developed for Saussurea polylepis (Asteraceae), a vulnerable species with very limited distribution in a few southwestern continental islands of the Korean peninsula, in order to facilitate future population genetic studies.Methods and resultsBased on the Illumina sequence data, a total of 21 microsatellite primer pairs were designed and tested for their suitability. Nineteen of these primers, with two to 11 alleles per locus, were polymorphic in three natural populations of S. polylepis. The levels of expected and observed heterozygosity ranged from 0.000 to 0.842 and 0.000 to 0.933, respectively. Sixteen of these simple sequence repeat (SSR) markers were successfully cross-amplified in five congeneric species, namely S. gracilis, S. grandifolia, and S. tanakae for all 21 loci, and S. maximowiczii and S. pulchella for 18 loci.ConclusionsThe SSR markers developed here will be useful for future population genetic studies on S. polylepis and related species.
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Project description:Deconstructing ribosomal DNA: from the sequence to the chromosome across the Tree-of-Life (rDNA-LIFE)
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Project description:Understanding how species adapt to extreme environments is an extension of the main goals of evolutionary biology. While alpine plants are an ideal system for investigating the genetic basis of high-altitude adaptation, genomic resources in these species are still limited. In the present study, we generated reference-level transcriptomic data of five Saussurea species through high-throughput sequencing and de novo assembly. Three of them are located in the highland of the Qinghai-Tibet Plateau (QTP), and the other two are close relatives distributed in the lowland. A series of comparative and evolutionary genomics analyses were conducted to explore the genetic signatures of adaptive evolution to high-altitude environments. Estimation of divergence time using single-copy orthologs revealed that Saussurea species diversified during the Miocene, a period with extensive tectonic movement and climatic fluctuation on the QTP. We characterized gene families specific to the alpine species, including genes involved in oxidoreductase activity, pectin catabolic process, lipid transport, and polysaccharide metabolic process, which may play important roles in defense of hypoxia and freezing temperatures of the QTP. Furthermore, in a phylogenetic context with the branch model, we identified hundreds of genes with signatures of positive selection. These genes are involved in DNA repair, membrane transport, response to UV-B and hypoxia, and reproductive processes, as well as some metabolic processes associated with nutrient intake, potentially responsible for Saussurea adaptation to the harsh environments of high altitude. Overall, our study provides valuable genomic resources for alpine species and gained helpful insights into the genomic basis of plants adapting to extreme environments.
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Project description:BackgroundSaussurea is one of the most species-rich genera in the Cardueae, Asteraceae. There are approximately 40 Saussurea species distributed in Korea, with nearly 40% of them endemics. Infrageneric relationships remain uncertain due to insufficient resolutions and low statistical support. In this study, we sequenced the plastid genomes of five Korean endemic Saussurea (S. albifolia, S. calcicola, S. diamantica, S. grandicapitula, and S. seoulensis), and comparative analyses including two other endemics (S. chabyoungsanica and S. polylepis) were conducted.ResultsThe plastomes of Korean endemics were highly conserved in gene content, order, and numbers. Exceptionally, S. diamantica had mitochondrial DNA sequences including two tRNAs in SSC region. There were no significant differences of the type and numbers of SSRs among the seven Korean endemics except in S. seoulensis. Nine mutation hotspots with high nucleotide diversity value (Pi > 0.0033) were identified, and phylogenetic analysis suggested that those Korean endemic species most likely evolved several times from diverse lineages within the genus. Moreover, molecular dating estimated that the Korean endemic species diverged since the late Miocene.ConclusionsThis study provides insight into understanding the plastome evolution and evolutionary relationships of highly complex species of Saussurea in Korean peninsula.
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Project description:Hieracium sinoaestivum Sennikov sp. nov. is described as new to science and illustrated. This presumably apomictic species is solely known from two old collections made in a single locality in the Shanxi Province of China. It belongs to the hybridogenous group Hieracium sect. Aestiva (Hieracium sect. Prenanthoidea × Hieracium sect. Umbellata) and is most similar to Hieracium veresczaginii from southern Siberia. The new species occurs at low altitudes in the forest belt of Lülian Mts. and belongs to taiga forest elements.
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