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Coordination of economics spectra in leaf, stem and root within the genus Artemisia along a large environmental gradient in China
No full textAim: The plant economics spectrum provides a fundamental framework for under- standing functional trait variation along environmental gradients. However, it is un- clear whether there is a general whole -plant economics spectrum across organs at the finer taxonomic scale (e.g. within genera), and if there is, which factors affect the trait coordination of the different organs. Here, we examined whether resource eco- nomics spectra of different organs (i.e. leaf, stem and root) can be integrated at the whole -plant level within a single genus, and how environment, intraspecific variation and taxonomic scale shape the whole -plant spectrum.Location: China.Time period: 2018. Major taxa studied: Artemisia.Methods: We sampled 1,022 individuals of 62 Artemisia species in central and eastern China to test trait coordination patterns from organ to whole -plant level. From the resource economics spectrum perspective, 15 traits were chosen to represent the trade -off between structural and nutrient investments, including organs' C, N, P and dry matter content, specific leaf area, specific stem length and specific root length. Results: Pairwise trait correlations and the trade -off patterns along the resource eco- nomic axis were consistent at both organ and whole -plant levels. Environmental gra- dients did not strongly affect the correlations among leaf, stem and root economics spectra, that is, the intraspecific variation weakened but did not mask this coordina- tion. Taxonomic scale did not affect the degree of trait coordination as the genus -wide whole -plant economics spectrum also emerged within each of the three subgenera.Main conclusions: Our results support the hypothesis that the coordination of eco- nomics spectra across organs forms a whole -plant economics spectrum represent- ing a fast- slow' resource management strategy, which is robust to recent evolution (genotypic variation, even for species within a single genus) and present -day environ- mental variation. Further studies should elucidate in which circumstances or phyloge- netic branches the coordinated pattern found for Artemisia is representative of other widely distributed genera
Interspecific and intraspecific trait variability differentially affect community-weighted trait responses to and recovery from long-term drought
No full text1. Plant traits are useful proxies of plant strategies and can influence community and ecosystem responses to climate extremes, such as severe drought. Few studies, however, have investigated both the immediate and lagged effects of drought on community-weighted mean (CWM) plant traits, with even less re- search on the relative roles of interspecific vs. intraspecific trait variability in such responses. 2. We experimentally reduced growing season precipitation by 66% in two cold semi arid grassland sites in northern China for four consecutive years to explore the drought resistance of CWM traits as well as their recovery 2 years follow- ing the drought. In addition, we isolated the effects of both interspecific and intraspecific trait variability on shifts in CWM traits. 3. At both sites, we observed significant effects of drought on interspecific and intraspecific trait variability which, in some cases, led to significant changes in CWM traits. For example, drought led to reduced CWM plant height and leaf phosphorous content, but increased leaf carbon content at both sites, with re- sponses primarily due to intraspecific trait shifts. Surprisingly, these CWM traits recovered completely 2 years after the extreme drought. Intraspecific trait vari- ability influenced CWM traits via both positive and negative covariation with interspecific trait variability during drought and recovery phases. 4. These findings highlight the important role of interspecific and intraspecific trait variability in driving the response and recovery of CWM traits following ex- treme, prolonged drought
Integration of hotspot identification, gap analysis, and niche modeling supports the conservation of Chinese threatened higher plants
No full textA significant fraction of higher plants in China are threatened due to dramatic landscape transformation and increasing climate change. However, the conservation effectiveness of threatened higher plants (THPs) and their response to climate change are still underexplored to date. Based on the latest list of THPs in China, we obtained 102 593 occurrence records with latitude and longitude for 3858 THPs. By integrating the distribution patterns of three biodiversity indexes (i.e., species richness, species complementarity, and weighted endemism) and 10 plant categories, we identified hotspots for THPs and calculated the conservation effectiveness of nature reserves. We then selected 1959 THPs to project the shift of species richness and range sizes under climate change (representative concentration pathway [RCP] 2.6 and RCP 8.5). In total, 16 hotspot areas covering 7.38% of Chinese land area and containing 91.73% of THPs were identified. Current nature reserves protected 35.05% of hotspots, 73.07% of all THPs, and 56.64% of narrow-ranged species. By the 2070s, the species richness of THPs were predicted to decrease in Southeast and Central China, and 42.42% (RCP 2.6) and 51.40% (RCP 8.5) of the 1959 THPs would confront habitat contraction. Future conservation efforts should focus on the conservation gaps and carry out targeted conservation for THPs with narrow distribution range. In order to cope with climate change, the hotspots with relatively low species loss can serve as important areas to contain current species diversity and the areas with high species gain offer opportunities for ex-situ conservation of THPs
The determiner of photosynthetic acclimation induced by biochemical limitation under elevated CO2 in japonica rice
No full textPhotosynthetic acclimation to prolonged elevated CO2 could be attributed to the two limited biochemical capacity, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation and ribulose-1,5-bisphosphate (RuBP) regeneration, however, which one is the primary driver is unclear. To quantify photosynthetic acclimation induced by biochemical limitation, we investigated photosynthetic characteristics and leaf nitrogen allocation to photosynthetic apparatus (Rubisco, bioenergetics, and light-harvesting complex) in a japonica rice grown in open-top chambers at ambient CO2 and ambient CO2+200 mu mol mol- 1 (e [CO2]). Results showed that photosynthesis was stimulated under e [CO2], but concomitantly, photosynthetic acclimation obviously occurred across the whole growth stages. The content of leaf nitrogen allocation to Rubisco and biogenetics was reduced by e [CO2], while not in light-harvesting complex. Unlike the content, there was little effects of CO2 enrichment on the percentage of nitrogen allocation to photosynthetic components. Additionally, leaf nitrogen did not reallocate within photosynthetic apparatus until the imbalance of sink-source under e [CO2]. The contribution of biochemical limitations, including Rubisco carboxylation and RuBP regeneration, to photosynthetic acclimation averaged 36.2% and 63.8% over the growing seasons, respectively. This study suggests that acclimation of photosynthesis is mainly driven by RuBP regeneration limitation and highlights the importance of RuBP regeneration relative to Rubisco carboxylation in the future CO2 enrichment
Bioinformatics analysis and function prediction of NBS-LRR gene family in Broussonetia papyrifera
No full textMost of the currently available disease resistance (R) genes have NBS (nucleotide-binding site) and LRR (leucine-rich-repeat) domain which belongs to the NBS-LRR gene family. The whole genome sequencing of Broussonetia papyrifera provides an important bioinformatics database for the study of the NBS-LRR gene family. In this study, 328 NBS-LRR family genes were identified and classified in B. papyrifera according to different classification schemes, where there are 92 N types, 47 CN type, 54 CNL type, 29 NL types, 55 TN type, and 51 TNL type. Subsequently, we conducted bioinformatics analysis of the NBS-LRR gene family. Classification, motif analysis of protein sequences, and phylogenetic tree studies of the NBS-LRR genes in B. papyrifera provide important basis for the functional study of NBS-LRR family genes. Additionally, we performed structural analysis of the chromosomal location, physicochemical properties, and sequences identified by genetic characterization. In addition, through the analysis of GO enrichment, it was found that NBS-LRR genes were involved in defense responses and were significantly enriched in biological stimulation, immune response, and abiotic stress. In addition, we found that Bp06g0955 was the most sensitive to low temperature and encoded the RPM1 protein by analyzing the low temperature transcriptome data of B. papyrifera. Quantitative results of gene expression after 48 h of Fusarium infection showed that Bp01g3293 increased 14 times after infection, which encodes RPM1 protein. The potential of NBS-LRR gene responsive to biotic and abiotic stresses can be exploited to improve the resistance of B. papyrifera
Enhanced foliar 15N enrichment with increasing nitrogen addition rates: Role of plant species and nitrogen compounds
No full textDetermining the abundance of N isotope (delta N-15) in natural environments is a simple but powerful method for providing integrated information on the N cycling dynamics and status in an ecosystem under exogenous N inputs. However, whether the input of different N compounds could differently impact plant growth and their N-15 signatures remains unclear. Here, the response of N-15 signatures and growth of three dominant plants (Leymus chinensis, Carex duriuscula, and Thermopsis lanceolata) to the addition of three N compounds (NH4HCO3, urea, and NH4NO3) at multiple N addition rates were assessed in a meadow steppe in Inner Mongolia. The three plants showed different initial foliar delta N-15 values because of differences in their N acquisition strategies. Particularly, T. lanceolata (N-2-fixing species) showed significantly lower N-15 signatures than L. chinensis (associated with arbuscular mycorrhizal fungi [AMF]) and C. duriuscula (associated with AMF). Moreover, the foliar delta N-15 of all three species increased with increasing N addition rates, with a sharp increase above an N addition rate of similar to 10 g N m(-2) year(-1). Foliar delta N-15 values were significantly higher when NH4HCO3 and urea were added than when NH4NO3 was added, suggesting that adding weakly acidifying N compounds could result in a more open N cycle. Overall, our results imply that assessing the N transformation processes in the context of increasing global N deposition necessitates the consideration of N deposition rates, forms of the deposited N compounds, and N utilization strategies of the co-existing plant species in the ecosystem
Long-term mowing reinforces connections between soil microbial and plant communities in a temperate steppe
No full textPurpose Mowing is an important management practice in the Inner Mongolia grassland and can significantly regulate plant and soil microbial communities. However, impact of long-term mowing on soil microbiota has been rarely evaluated in grassland ecosystems, and the effects of plant community on belowground microbiota under mowing were mainly focused on plant alpha-diversity, while the role of plant beta-diversity is largely unknown. Methods We examined the soil bacterial, fungal and protistan communities under the influence of a 17-year mowing treatment in a natural grassland of Inner Mongolia, and studied the relationship between the soil microbial communities and plant/soil parameters, and the correlations between beta-diversity of the soil microbial and plant communities. We also constructed co-occurrence networks to investigate the legacy of mowing on the interactions between plant community and the three microbial groups (bacteria, fungi, protists). Results We found that long-term mowing had significant effects on the community structures of plants and the three microbial groups. The microbial community structures mainly correlated to the plant parameters including aboveground biomass, plant litter, root carbon-to-nitrogen ratio, and plant Shannon index rather than to soil properties. Moreover, beta-diversity of the soil microbial communities was significantly regulated by plant community beta-diversity. Furthermore, mowing enhanced plant-microbe interactions in the networks under long-term mowing. Conclusions Long-term mowing significantly alters plant and soil microbial community compositions and can reinforce their connections. The induced shifts of plant community attributes by long-term mowing rather than soil properties may be more effective factors in shaping soil microbial communities in grasslands
Reorganization of three-dimensional chromatin architecture in Medicago truncatula under phosphorus deficiency
No full textEmerging evidence reveals that the three-dimensional (3D) chromatin architecture plays a key regulatory role in various biological processes of plants. However, information on the 3D chromatin architecture of the legume model plant Medicago truncatula and its potential roles in the regulation of response to mineral nutrient deficiency are very limited. Using high-resolution chromosome conformation capture sequencing, we identified the 3D genome structure of M. truncatula in terms of A/B compartments, topologically associated domains (TADs) and chromatin loops. The gene density, expressional level, and active histone modification were higher in A compartments than in B compartments. Moreover, we analysed the 3D chromatin architecture reorganization in response to phosphorus (P) deficiency. The intra-chromosomal cis-interaction proportion was increased by P deficiency, and a total of 748 A/B compartment switch regions were detected. In these regions, density changes in H3K4me3 and H3K27ac modifications were associated with expression of P deficiency-responsive genes involved in root system architecture and hormonal responses. Furthermore, these genes enhanced P uptake and mobilization by increasing root surface area and strengthening signal transduction under P deficiency. These findings advance our understanding of the potential roles of 3D chromatin architecture in responses of plants in general, and in particular in M. truncatula, to P deficiency. Reorganization of the 3D chromatin architecture is associated with transcriptional regulation to enhance phosphorus uptake and mobilization in Medicago truncatulaunder phosphorus deficiency
5300-Year-old soil carbon is less primed than young soil organic matter
No full textSoils harbor more than three times as much carbon (C) as the atmosphere, a large fraction of which (stable organic matter) serves as the most important global C reservoir due to its long residence time. Litter and root inputs bring fresh organic matter (FOM) into the soil and accelerate the turnover of stable C pools, and this phenomenon is termed the priming effect (PE). Compared with knowledge about labile soil C pools, very little is known about the vulnerability of stable C to priming. Using two soils that substantially differed in age (500 and 5300 years before present) and in the degree of chemical recalcitrance and physical protection of soil organic matter (SOM), we showed that leaf litter amendment primed 264% more organic C from the young SOM than from the old soil with very stable C. Hierarchical partitioning analysis confirmed that SOM stability, reflected mainly by available C and aggregate protection of SOM, is the most important predictor of leaf litter-induced PE. The addition of complex FOM (i.e., leaf litter) caused a higher bacterial oligotroph/copiotroph (K-/r-strategists) ratio, leading to a PE that was 583% and 126% greater than when simple FOM (i.e., glucose) was added to the young and old soils, respectively. This implies that the PE intensity depends on the chemical similarity between the primer (here FOM) and SOM. Nitrogen (N) mining existed when N and simple FOM were added (i.e., Glucose+N), and N addition raised the leaf litter-induced PE in the old soil that had low N availability, which was well explained by the microbial stoichiometry. In conclusion, the PE induced by FOM inputs strongly decreases with increasing SOM stability. However, the contribution of stable SOM to CO2 efflux cannot be disregarded due to its huge pool size
Linalool: A ubiquitous floral volatile mediating the communication between plants and insects
No full textTerpenoids, one of the most important plant volatiles, mediate the communication between plants and pollinators, herbivores as well as pathogens. Recently, researchers have shown intensive interest in the complicated interactions. Linalool, an acyclic monoterpene, is one of the common flavor-related volatiles across the plant kingdom. In this review, we summarized the biosynthesis and transcriptional regulation of terpenoids, and then focused on the biological function of linalool in plant-insect interactions. We found that flowers emitting linalool as the dominant volatile appeal to broad assemblages of pollinators, while some pollinators typically have strong preferences for these flowers as well. Hereinto, moths and bees are the main pollinators of linalool-dominant flowers. Additionally, linalool produced by plants could defend against insect pests and pathogens. It is noteworthy that the two enantiomers of linalool have distinct functions. (S)-(+)-linalool mainly attracts pollinators, while (R)-(-)-linalool seems to act as insect repellents. Further research on the biofunctional diversity and genetic mechanisms of linalool enantiomers will reveal the complexity of plant survival strategies, and the increasing understanding of the molecular mechanisms underlying their biosynthesis and transcriptional regulation will provide theoretical foundation and practical basis for directional transformation of plants