Three new, early diverging Carex (Cariceae, Cyperaceae) lineages from East and Southeast Asia with important evolutionary and biogeographic implications

Carexqingyuanensis (Cyperaceae), a new species from Guangdong, China

Carexqingyuanensis, a new species of Cyperaceae from Guangdong Province, China, is described and illustrated. The new species is morphologically similar to Carexpeliosanthifolia F. T. Wang & Tang ex P. C. Li, but it can be distinguished by the racemose inflorescence branches appearing single (rarely binate or ternate) (vs. binate or ternate), one (rarely two or three) (vs. 1-3) spiked, male part of linear-cylindrical spikes much longer than the female part (vs. just male part short-cylindrical and slightly longer than female part), style base thickened (vs. not thickened) and perigynium horizontally patent with a short (vs. long and excurved) beak. Phylogenetic analysis, based on the two nuclear DNA regions (ETS 1f and ITS) and three chloroplast DNA regions (matK, ndhF and rps16), suggests that the new species belongs to sect. Siderostictaes.s. of subg. Siderosticta and shows a closer phylogenetic relationship to Carexscaposa C. B. Clarke.

Carex borealifujianica (Cyperaceae), a new species of the core Carex clade from Fujian, southeastern China

A new species, Carex borealifujianica Y.F. Lu & X.F. Jin (Cyperaceae, sect. Occlusae of core Carex clade) is described and illustrated from northern Fujian, China. In addition to morphological comparisons with its relatives, comparative micromorphology of utricles and achenes of seven species in Carex sect. Occlusae was examined. Micromorphology of utricles and achenes revealed the similarity of Carex borealifujianica and C. ligulata. Morphologically, this new species is similar to Carex ligulata in having lateral spikes remote and densely flowered, as well as utricles densely hispidulous, but differs in having 2 or 3 narrowly clavate staminate spikes, leaves 2.5–5 mm wide with sheaths sparsely pilose, and achenes emarginate at the apex. The phylogenetic analysis from two nuclear DNA regions (ETS and ITS) and two chloroplast DNA regions (matK and trnL-F) of 68 taxa resolved C. borealifujianica as a distinct species.

 Carexmalipoensis (Cyperaceae), a new species from southeast Yunnan, China

Carexmalipoensis, a new species from southeast Yunnan, China, is here described and illustrated. It is morphologically similar to C.trichophylla in sect. Euprepes, but differs from it by its longer inflorescences and peduncles, pendulous spikes, hispidulous female glumes, densely hispidulous utricles, and longer nutlets.

Lipidomic metabolism associated with acetic acid priming-induced salt tolerance in Carex rigescens

Acetic acid priming may mitigate salt stress to plants by modulating lipid metabolism. Carex rigescens is a stress-tolerant turfgrass species with a widespread distribution in north China. The objective of this study was to figure out whether modification of lipid profiles, including the contents, compositions and saturation levels of leaf lipids, may contribute to acetic acid modulated salt tolerance in C. rigescens. Plants of C. rigescens were primed with or without acetic acid (30 mM) and subsequently exposed to salt stress (300 mM NaCl) for 15 days. Salt stress affected the physiological performance of C. rigescens, while acetic acid-primed plants showed significantly lower malondialdehyde content, proline content, and electrolyte leakage than non-primed plants under salt stress. Acetic acid priming enhanced the contents of phospholipids and glycolipids involved in membrane stabilization and stress signaling (phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, digalactosyl diacylglycerol, monogalactosyl diacylglycerol, and sulfoquinovosyldiacylglycerol), reduced the content of toxic lipid intermediates (free fatty acids) during subsequent exposure to salt stress. Furthermore, expression levels of genes involved in lipid metabolism such as CK and PLDα changed due to acetic acid priming. These results demonstrated that acetic acid priming could enhance salt tolerance of C. rigescens by regulating lipid metabolism. The lipids could be used as biomarkers to select for salt-tolerant grass germplasm.

Comparative time-course transcriptome analysis in contrasting Carex rigescens genotypes in response to high environmental salinity

Soil salinization is one of most crucial environmental problems around the world and negatively affects plant growth and production. Carex rigescens is a turfgrass with favorable stress tolerance and great application prospect in salinity soil remediation and utilization; however, the molecular mechanisms behind its salt stress response are unknown. We performed a time-course transcriptome analysis between salt tolerant 'Huanghua' (HH) and salt sensitive 'Beijing' (BJ) genotypes. Physiological changes within 24 h were observed, with the HH genotype exhibiting increased salt tolerance compared to BJ. 5764 and 10752 differentially expressed genes were approved by transcriptome in BJ and HH genotype, respectively, and dynamic analysis showed a discrepant profile between two genotypes. In the BJ genotype, genes related to carbohydrate metabolism and stress response were more active and ABA signal transduction pathway might play a more important role in salt stress tolerance than in HH genotype. In the HH genotype, unique increases in the regulatory network of transcription factors, hormone signal transduction, and oxidation-reduction processes were observed. Moreover, trehalose and pectin biosynthesis and chitin catabolic related genes were specifically involved in the HH genotype, which may have contributed to salt tolerance. Moreover, some candidate genes like mannan endo-1,4-beta-mannosidase and EG45-like domain-containing protein are highlighted for future research about salt stress resistance in C. rigescens and other plant species. Our study revealed unique salt adaptation and resistance characteristics of two C. rigescens genotypes and these findings could help to enrich the currently available knowledge and clarify the detailed salt stress regulatory mechanisms in C. rigescens and other plants.

Overexpression of CrCOMT from Carex rigescens increases salt stress and modulates melatonin synthesis in Arabidopsis thaliana

CrCOMT, a COMT gene in Carex rigescens, was verified to enhance salt stress tolerance in transgenic Arabidopsis. High salinity severely restricts plant growth and development while melatonin can alleviate salt damage. Caffeic acid O-methyltransferase (COMT) plays an important role in regulating plant growth, development, and stress responses. COMT could also participate in melatonin biosynthesis. The objective of this study was to identify CrCOMT from Carex rigescens (Franch.) V. Krecz, a stress-tolerant grass species with a widespread distribution in north China, and to determine its physiological functions and regulatory mechanisms that impart tolerance to salt stress. The results showed that the transcription of CrCOMT exhibited different expression patterns under salt, drought, and ABA treatments. Transgenic Arabidopsis with the overexpression of CrCOMT exhibited improved growth and physiological performance under salt stress, such as higher lateral root numbers, proline level, and chlorophyll content, than in the wild type (WT). Overexpression of CrCOMT also increased dehydration tolerance in Arabidopsis. The transcription of salt response genes was more highly activated in transgenic plants than in the WT under salt stress conditions. In addition, the melatonin content in transgenic plants was higher than that in the WT after stress treatment. Taken together, our results indicated that CrCOMT may positively regulate stress responses and melatonin synthesis under salt stress.

The rediscovery of the rare Vietnamese endemic Eriophorum scabriculme redefines generic limits in the Scirpo-Caricoid Clade (Cyperaceae)

For those familiar with boreal bogs and wet tundra, species of Eriophorum (“the cotton grasses”) will undoubtedly represent some of the most striking and memorable taxa they have encountered. This small genus of 20 Holarctic sedge species (Cyperaceae) is remarkable because its inflorescences produce large, brilliantly white to rusty-red cottony masses when its flowers develop a perianth of highly elongated bristles after anthesis. In this study, we document the rediscovery of Eriophorum scabriculme, a narrow Vietnamese endemic known from only two collections made approximately 7 km apart near Sa Pa in Lào Cai Province over 75 years ago. Using plastid DNA sequences (matK, ndhF), embryology, and morphology, we test whether E. scabriculme is aligned within the Scirpo-Caricoid Clade (genus Khaosokia and tribes Cariceae, Dulichieae, Scirpeae, and Sumatroscirpeae) or the Ficinia Clade (Cypereae), and we determine whether its unique character combinations (≥10 elongated bristles, reduced sheathing basal leaves, 1–4 spikelets) could be evidence for a new genus or simply mark it as an unusual species within currently recognised genera. In addition, we document the discovery of seven new populations, and we extend its range westward to Lai Châu Province and southward in Lào Cai Province by more than 47 km. Our results demonstrate that Eriophorum scabriculme is best treated in the genus Trichophorum, thus re-circumscribing both genera and their limits with Scirpus s.str. In addition, we emend the description of Trichophorum scabriculme (Beetle) J.R.Starr, Lév.-Bourret & B.A. Ford, provide the first pictures and accurate illustration of the species, and assess its conservation status in Vietnam (VU, Vulnerable). Our study corroborates the fact that in such a diverse and taxonomically difficult family like the sedges, conspicuous characters like highly elongated bristles may be useful for dividing diversity, but they are no guarantee that the groups they mark are natural.

Timing and ecological priority shaped the diversification of sedges in the Himalayas

BACKGROUND

Diversification patterns in the Himalayas have been important to our understanding of global biodiversity. Despite recent broad-scale studies, the most diverse angiosperm genus of the temperate zone-Carex L. (Cyperaceae), with ca. 2100 species worldwide-has not yet been studied in the Himalayas, which contains 189 Carex species. Here the timing and phylogenetic pattern of lineage and ecological diversification were inferred in this ecologically significant genus. We particularly investigated whether priority, adaptation to ecological conditions, or both explain the highly successful radiation of the Kobresia clade (ca. 60 species, of which around 40 are present in the Himalayas) of Himalayan Carex.

METHODS

Phylogenetic relationships were inferred using maximum likelihood analysis of two nuclear ribosomal DNA (nrDNA) regions (ITS and ETS) and one plastid gene (matK); the resulting tree was time-calibrated using penalized likelihood and a fossil calibration at the root of the tree. Biogeographical reconstruction for estimation of historical events and ancestral ranges was performed using the dispersal-extinction-cladogenesis (DEC) model, and reciprocal effects between biogeography and diversification were inferred using the geographic state speciation and extinction (GeoSSE) model. Climatic envelopes for all species for which mapped specimen data available were estimated using climatic data from WORLDCLIM, and climatic niche evolution was inferred using a combination of Ornstein-Uhlenbeck models of shifting adaptive optima and maximum likelihood inference of ancestral character states under a Brownian motion model.

RESULTS

The Himalayan Carex flora represents three of the five major Carex clades, each represented by multiple origins within the Himalayas. The oldest Carex radiation in the region, dating to ca. 20 Ma, near the time of Himalayan orogeny, gave rise to the now abundant Kobresia clade via long-distance dispersal from the Nearctic. The Himalayan Carex flora comprises a heterogeneous sample of diversifications drawn from throughout the cosmopolitan, but mostly temperate, Carex radiation. Most radiations are relatively recent, but the widespread and diverse Himalayan Kobresia radiation arose at the early Miocene. The timing and predominance of Kobresia in high-elevation Himalayan meadows suggests that Kobresia may have excluded other Carex lineages: the success of Kobresia in the Himalayas, in other words, appears to be a consequence largely of priority, competitive exclusion and historical contingency.

Selection and validation of reference genes for target gene analysis with quantitative real-time PCR in the leaves and roots of Carex rigescens under abiotic stress

Carex rigescens is an ornamental turfgrass in northern China which has a relatively low maintenance cost and robust tolerance to many adverse environmental conditions, so it could be considered a new material for researching into plant stress resistance. However, suitable reference genes are vacant for obtaining reliable results in quantitative real-time PCR (qRT-PCR) analysis of C. rigescens in adversity research. In this study, we tested the expression stability of nine potential reference genes in leaves and roots under five different abiotic stress conditions, including cold, salt, heat, osmotic and cadmium (Cd). We then selected the best reference genes according to the analysis results calculated by three algorithmic programs (geNorm, NormFinder and BestKeeper) and used the RankAggreg package to merge the outputted data. The results showed that combinations of at least two reference genes should be used for reliable normalization except in heat-treated root samples, which require three reference genes. eIF-4α, GADPH, SAND and PEPKR1 and their combination were found to be the most stably expressed reference genes, while SAM, TUA-α and UPL7 were the three least stable reference genes among most of experimental samples. In addition, five stress-induced genes (Cu-Zn SOD, P5CS, LEA, GST, and APX) were chosen to verify the stability of the selected reference genes in various tissues and under various stress conditions. The results of this study will provide an important fundamental basis both for gene expression verification for transcriptomic and proteomic analyses and for gene expression analysis for future gene function research in C. rigescens.

Why are there so many sedges? Sumatroscirpeae, a missing piece in the evolutionary puzzle of the giant genus Carex (Cyperaceae)

For over a century, the origins and mechanisms underlying the diversification of the enormous temperate genus Carex (>2100 species; Cariceae, Cyperaceae) have remained largely speculative. Characteristics such as its diverse ecology, varied biogeography, and intriguing cytology have made Carex a powerful model for studying plant evolution, but its uncertain sister-group relationships hinder its use in studies that depend on accurate ancestral state estimates and biogeographic inferences. To identify the sister to Carex, we estimated the phylogeny of all genera in the Cariceae-Dulichieae-Scirpeae clade (CDS) using three plastid and two nuclear ribosomal markers. Ancestral state reconstructions of key characters were made, and a time-calibrated tree estimated. Carex is strongly supported as sister to the rare East Asian Sumatroscirpus, sole genus of a new tribe, Sumatroscirpeae trib. nov. Believed to be unique to Carex, the perigynium (prophyllar bract enclosing a flower) is in fact a synapomorphy shared with this small tribe (∼4 species) that appeared 36 Mya. We thus suggest the initial key innovation in the remarkable diversification of Carex is not the perigynium, but could be the release of mechanical constraints on perigynia through spikelet truncation, resulting in novel adaptive morphologies. Monoecy, chromosomal change, and rapid inflorescence development enabling phenological isolation may also be involved. The tiny tribe Sumatroscirpeae will provide unprecedented insights into the inflorescence homology, evolution, diversification, and biogeographic history of its sister-group Carex, one of the world's most diverse plant lineages.

Saproamanita, a new name for both Lepidella E.-J. Gilbert and Aspidella E.-J. Gilbert (Amaniteae, Amanitaceae)

The genus Amanita has been divided into two monophyletic taxa, Amanita, an ectomycorrhizal genus, and Aspidella, a saprotrophic genus. The controversies and histories about recognition of the two genera based on trophic status are discussed. The name Aspidella E.-J. Gilbert is shown to be illegitimate and a later homonym of Aspidella E. Billings, a well-known generic name for an enigmatic fossil sometimes classified as a fungus or alga. The name Saproamanita is coined to replace Aspidella E.-J. Gilbert for the saprotrophic Amanitas, and a selection of previously molecularly analyzed species and closely classified grassland species are transferred to it along with selected similar taxa. The type illustration for the type species, S. vittadinii, is explained and a subgeneric classification accepting Amanita subgen. Amanitina and subgen. Amanita is proposed. Validation of the family name, Amanitaceae E.-J. Gilbert dating from 1940, rather than by Pouzar in 1983 is explained.