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MOLECULAR AND MORPHOLOGICAL EVIDENCE SUPPORTS THE INCLUSION OF DEINOSTIGMA INTO METAPETROCOSMEA (GESNERIACEAE)1,2
No full textMetapetrocosnrea W. T. Wang and Deinostigma W. T. Wang & Z. Y. Li were originally monotypic with M. peltata (Merr. & Chun) W T. Wang and D. poilanei (Pellegr.) W. T. Wang & Z. Y. Li, respectively. Recent molecular phylogenetic research expanded Deinostigma to include several species previously transferred from Chirita. D. Don to Primulina Hance. However, the relationship between Metapetrocosmea and Deinostigma has not been well addressed. In the present study, the type species of Metapetrocosmea and Deinostignut were sampled together with related taxa, and the systematic relationships were reexamined using the nuclear ribosomal internal and external transcribed spacer regions (ITS and ETS) and four chloroplast regions (rpL32-trnL, rpsI6, trnH-psbA, trriL-F). Phylogenetic analyses demonstrate that M. peltata is embedded in the species of Deinostigma and sister to D. poilanei. All of these species form a highly supported branch, i.e., Metaperrocosmea-Deiruzstigma Glade, which is sister to Oreoclutris Bend'. Morphological analyses show that species in the Mehipetrocosmea-Deinostigma Glade share a series of morphological traits, i.e., alternate leaves, arcuate filaments, densely lanate anthers with the hair surface covered with granular or vermiform appendages, bilobed stigma that vary from dorsal to ventral and almost equal in size to a dorsal-ventral oblique lamella with the dorsal one sterile, hooked hairs and T-shaped glandular hairs occurring on the whole plant, and riblike seed surfaces. Both molecular and morphological evidence strongly suggest that the Metapetrocasmea-Deinostigma Glade is monophyletic and should be combined into a single genus, i.e., Metapetrocosmea W. T. Wang. Therefore, we present a taxonomic treatment for this group
Substantial non-growing season carbon dioxide loss across Tibetan alpine permafrost region
No full textOne of the major uncertainties for projecting permafrost carbon (C)-climate feedback is a poor representation of the non-growing season carbon dioxide (CO2) emissions under a changing climate. Here, combining in situ field observations, regional synthesis and a random forest model, we assessed contemporary and future soil respired CO2 (i.e., soil respiration, R-s) across the Tibetan alpine permafrost region, which has received much less attention compared with the Arctic permafrost domain. We estimated the regional mean R-s of 229.8, 72.9 and 302.7 g C m(-2) year(-1) during growing season, non-growing season and the entire year, respectively; corresponding to the contemporary losses of 296.9, 94.3 and 391.2 Tg C year(-1) from this high-altitude permafrost-affected area. The non-growing season R-s accounted for a quarter of the annual soil CO2 efflux. Different from the prevailing view that temperature is the most limiting factor for cold-period CO2 release in Arctic permafrost ecosystems, precipitation determined the spatial pattern of non-growing season R-s on the Tibetan Plateau. Using the key predictors, model extrapolation demonstrated additional losses of 38.8 and 74.5 Tg C from the non-growing season for a moderate mitigation scenario and a business-as-usual emissions scenario, respectively. These results provide a baseline for non-growing season CO2 emissions from high-altitude permafrost areas and help for accurate projection of permafrost C-climate feedback
Tallo: A global tree allometry and crown architecture database
No full textData capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: . To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle
Greater soil microbial biomass loss at low frequency of N addition in an Inner Mongolia grassland
No full textSoil microbial biomass is critical for biogeochemical cycling and serves as precursor for carbon (C) sequestration. The anthropogenic nitrogen (N) input has profoundly changed the pool of soil microbial biomass. However, traditional N deposition simulation experiments have been exclusively conducted through infrequent N addition, which may have caused biased effects on soil microbial biomass compared with those under the natural and continuous N deposition. Convincing data are still scarce about how the different N addition frequencies affect soil microbial biomass. By independently manipulating the frequencies (2 times vs. 12 times N addition yr(-1)) and the rates (0-50 g N m(-2) yr(-1)) of N addition, our study aimed to examine the response of soil microbial biomass C (MBC) to different N addition frequencies with increasing N addition rates. Soil MBC gradually decreased with increasing N addition rates under both N addition frequencies, while the soil MBC decreased more at low frequency of N addition, suggesting that traditional studies have possibly overestimated the effects of N deposition on soil microbial biomass. The greater soil microbial biomass loss with low N frequency resulted from the intensified soil acidification, higher soil inorganic N, stronger soil C and N imbalance, less net primary production allocated to belowground and lower fungi to bacteria ratio. To reliably predict the effects of atmospheric N deposition on soil microbial functioning and C cycling of grassland ecosystems in future studies, it is necessary to employ both the dosage and the frequency of N addition
Circadian clock in plants: Linking timing to fitness
No full textEndogenous circadian clock integrates cyclic signals of environment and daily and seasonal behaviors of organisms to achieve spatiotemporal synchronization, which greatly improves genetic diversity and fitness of species. This review addresses recent studies on the plant circadian system in the field of chronobiology, covering topics on molecular mechanisms, internal and external Zeitgebers, and hierarchical regulation of physiological outputs. The architecture of the circadian clock involves the autoregulatory transcriptional feedback loops, post-translational modifications of core oscillators, and epigenetic modifications of DNA and histones. Here, light, temperature, humidity, and internal elemental nutrients are summarized to illustrate the sensitivity of the circadian clock to timing cues. In addition, the circadian clock runs cell-autonomously, driving independent circadian rhythms in various tissues. The core oscillators responds to each other with biochemical factors including calcium ions, mineral nutrients, photosynthetic products, and hormones. We describe clock components sequentially expressed during a 24-h day that regulate rhythmic growth, aging, immune response, and resistance to biotic and abiotic stresses. Notably, more data have suggested the circadian clock links chrono-culture to key agronomic traits in crops
Phylogenomic and morphological evidence reveal a new species of spider lily, Lycoris longifolia (Amaryllidaceae) from China
No full textLycoris longifolia, a new species from China, was described and illustrated here. Our phylogenomic evi-dence based on whole plastomes strongly supported the separate phylogenetic position of this new species, and morphologically it could also be distinguished by its long leaves with a distinct purplish-red midrib on the abaxial surface
Effects of stocking rate on the interannual patterns of ecosystem biomass and soil nitrogen mineralization in a meadow steppe of northeast China
No full textBackground and aims Understanding the effects of livestock grazing on the ecosystem biomass and soil nitrogen processes of grassland ecosystems is critical to improving knowledge on the mechanisms underlying grassland degradation and accurately assessing the influence of grazing management on grassland functions. Methods We examined the interannual patterns of ecosystem biomass and soil nitrogen mineralization in response to cattle grazing in a Chinese meadow steppe. The soil core incubation method was employed for soil N transfer estimation, whilst the fumigation extraction method, a modified Baermann funnel method and harvest method were used for various measurements of ecosystem biomass parameters. Results We found that cattle grazing caused consistent significant increases in soil temperature, irrespective of the stocking rate and year, whereas significant effects on soil moisture and edaphic properties were observed only in individual years and/or at specific stocking rates. Consistent positive effects at moderate stocking rates were observed for aboveground net primary production and soil nematode biomass in all study years. The across stocking rate pattern of N mineralization in response to cattle stocking appeared to be year-specific, although negative effects were found in most cases. In contrast, the interannual pattern of N mineralization was determined principally by the interannual patterns in precipitation and soil moisture and was much less affected by cattle grazing. Conclusions Soil N mineralization in this meadow steppe was affected by cattle grazing via two major mechanisms, i.e., its effects on the aboveground net primary production (ANPP) and thus the quantity of plant litter input into the soil and its effects on soil temperature and moisture. Overall, our study spanned the longest consecutive years with the broadest range of stocking rates thus far of its kind, which revealed for the first time that the soil nitrogen mineralization pattern with respect to stocking rate was year-specific. Our findings have important implications for adaptive management and sustainable utilization of Chinese grasslands
High association strengths are linked to phenotypic similarity, including plumage color and patterns, of participants in mixed-species bird flocks of southwestern China
No full textParticipants in mixed-species bird flocks (MSFs) have been shown to associate with species that are similar in body size, diet, and evolutionary history, suggesting that facilitation structures these assemblages. In addition, several studies have suggested that species in MSFs resemble each other in their plumage, but this question has not been systematically investigated for any MSF system. During the nonbreeding season of 2020 and 2021, we sampled 585 MSFs on 14 transects in 2 habitats of Tongbiguang Nature Reserve in western Yunnan Province, China. We performed social network analysis and the Multiple Regression Quadratic Assignment Procedure to evaluate the effect of 4 species traits (body size, overall plumage color, distinctive plumage patterns, and diet) and evolutionary history on species association strength at the whole-MSF and within-MSF levels. All 41 significant relationships showed that species with stronger associations were more similar in their various traits. Body size had the strongest effect on association strength, followed by phylogeny, plumage patterns, and plumage color; diet had the weakest effect. Our results are consistent with the hypotheses that the benefits of associating with phenotypically similar species outweigh the potential costs of interspecific competition, and that trait matching can occur in plumage characteristics, albeit more weakly than in other traits. Several explanations exist as to why similarities in plumage may occur in MSFs, including that they could reduce predators' ability to target phenotypically odd individuals. Whether trait matching in plumage occurs through assortative processes in ecological time or is influenced by co-evolution requires further study
Genomic basis of the giga-chromosomes and giga-genome of tree peony Paeonia ostii
No full textTree peony (Paeonia ostii) is an economically important ornamental plant native to China. It is also notable for its seed oil, which is abundant in unsaturated fatty acids such as alpha-linolenic acid (ALA). Here, we report chromosome-level genome assembly (12.28 Gb) of P. ostii. In contrast to monocots with giant genomes, tree peony does not appear to have undergone lineage-specific whole-genome duplication. Instead, explosive LTR expansion in the intergenic regions within a short period (similar to two million years) may have contributed to the formation of its giga-genome. In addition, expansion of five types of histone encoding genes may have helped maintain the giga-chromosomes. Further, we conduct genome-wide association studies (GWAS) on 448 accessions and show expansion and high expression of several genes in the key nodes of fatty acid biosynthetic pathway, including SAD, FAD2 and FAD3, may function in high level of ALAs synthesis in tree peony seeds. Moreover, by comparing with cultivated tree peony (P. suffruticosa), we show that ectopic expression of class A gene AP1 and reduced expression of class C gene AG may contribute to the formation of petaloid stamens. Genomic resources reported in this study will be valuable for studying chromosome/genome evolution and tree peony breeding
Conversion between duplicated genes generated by polyploidization contributes to the divergence of poplar and willow
No full textBackground Gene conversion has an important effect on duplicate genes produced by polyploidization. Poplar (Populus trichocarpa) and willow (Salix brachista) are leading models and excellent green plants in the Salicaceae. Although much attention has been paid to the evolution of duplicated genes in poplar and willow, the role of conversion between duplicates generated from polyploidization remains poorly understood. Results Here, through genomic synteny analyses, we identified duplicate genes generated by the Salicaceae common tetraploidization (SCT) in the poplar and willow genomes. We estimated that at least 0.58% and 0.25% of poplar and willow duplicates were affected by whole-gene conversion after the poplar-willow divergence, with more (5.73% and 2.66%) affected by partial-gene conversion. Moreover, we found that the converted duplicated genes were unevenly distributed on each chromosome in the two genomes, and the well-preserved homoeologous chromosome regions may facilitate the conversion of duplicates. Notably, we found that conversion maintained the similarity of duplicates, likely contributing to the conservation of certain sequences, but is essentially accelerated the rate of evolution and increased species divergence. In addition, we found that converted duplicates tended to have more similar expression patterns than nonconverted duplicates. We found that genes associated with multigene families were preferentially converted. We also found that the genes encoding conserved structural domains associated with specific traits exhibited a high frequency of conversion. Conclusions Extensive conversion between duplicate genes generated from the SCT contributes to the diversification of the family Salicaceae and has had long-lasting effects on those genes with important biological functions