Introduction
The stimulation of plant and microbial growth has been widely observed as a result of elevated CO
2
concentrations (eCO
2
), however, this stimulation could be influenced by various ...factors and their relative importance remains unclear.
Methods
A global meta-analysis was performed using 884 lines of observations collected from published papers, which analyzed the eCO
2
impact on plant and microbial biomass.
Results
A significant positive impact of eCO
2
was observed on various biomass measures, including aboveground biomass (20.5%), belowground biomass (42.6%), soil microbial biomass (10.4%), fungal biomass (11.0%), and bacterial biomass (9.2%). It was found that eCO
2
levels above 200 ppm had a greater impact on plant biomass compared to concentrations at or below 200 ppm. On the other hand, studies showed that positive effects on microbial biomass were more prominent at lower eCO
2
levels (≤200 ppm) than at higher levels (>200 ppm), which could be explained by soil nitrogen limitations. Importantly, our results indicated that aboveground biomass was controlled more by climatic and experimental conditions, while soil properties strongly impacted the stimulation of belowground and microbial biomass.
Discussion
Our results provided evidence of the eCO
2
fertilization effect across various ecosystem types, experimental methods, and climates, and provided a quantitative estimate of plant and soil microbial biomass sensitivity to eCO
2
. The results obtained in this study suggest that ecosystem models should consider climatic and edaphic factors to more accurately predict the effects of global climate change and their impact on ecosystem functions.
Carex L., a grass genus commonly known as sedges, is distributed worldwide and contributes constructively to turf management, forage production, and ecological conservation. The development of ...next-generation sequencing (NGS) technologies has considerably improved our understanding of transcriptome complexity of Carex L. and provided a valuable genetic reference. However, the current transcriptome is not satisfactory mainly because of the enormous difficulty in obtaining full-length transcripts.
In this study, we employed PacBio single-molecule long-read sequencing (SMRT) technology for whole-transcriptome profiling in Carex breviculmis. We generated 60,353 high-confidence non-redundant transcripts with an average length of 2302-bp. A total of 3588 alternative splicing events, and 1273 long non-coding RNAs were identified. Furthermore, 40,347 complete coding sequences were predicted, providing an informative reference transcriptome. In addition, the transcriptional regulation mechanism of C. breviculmis in response to shade stress was further explored by mapping the NGS data to the reference transcriptome constructed by SMRT sequencing.
This study provided a full-length reference transcriptome of C. breviculmis using the SMRT sequencing method for the first time. The transcriptome atlas obtained will not only facilitate future functional genomics studies but also pave the way for further selective and genic engineering breeding projects for C. breviculmis.
Abstract
The partitioning of belowground biomass (BGB) to aboveground biomass (AGB) is commonly described as the root-to-shoot ratio (R/S). Although a number of studies have shown that biodiversity ...can influence AGB and BGB in grasslands at the local and global scale, the global-scale patterns reflecting how plant diversity affects R/S and the factors controlling such effects remain unclear. In this study, we explored the global patterns and associated drivers of biomass partitioning responding to plant diversity by conducting a meta-analysis of 333 observations from 30 studies in grasslands worldwide. Overall, plant diversity significantly increased AGB, BGB, and total biomass, whereas significantly decreased R/S. The effects of plant diversity on biomass partitioning varied with experimental types. The effect size for AGB and BGB in the field was larger than in greenhouse experiments, but the effect size for R/S did not significantly differ between field and greenhouse experiments. Moreover, there was no significant relationship between R/S and species richness and experimental duration in greenhouse experiments. However, the effect size for AGB, BGB, and R/S increased logarithmically with species richness and experimental duration in the field experiments. Specifically, the effect size for R/S in the field experiments switched from negative to neutral as the species richness and experimental duration increased. Furthermore, the effect size for R/S was positively correlated with complementary effects of BGB, and it increased logarithmically with mean annual temperature (MAT) and precipitation. Structural equation models showed that species richness, experimental duration, and MAT impact R/S indirectly by changing the BGB. Overall, our findings suggest that plant mixtures invest less in BGB than monocultures, and highlight that low investment in BGB will disappear gradually over time as species richness increases.
Hydrogen generation and accumulation in confined spaces poses safety concerns due to its reactivity with oxygen to form explosions and the ability to embrittle metals. Various organic getters have ...been developed to eliminate hydrogen and minimize these undesired effects; however, these getters are usually powders with low molecular weights and are difficult to apply in complex structures. Polymer getters exhibit the promising features required for confined space applications, where could be readily processed into various shapes and forms. Unfortunately, polymer getters are relatively unexplored and their recorded performances are far from satisfactory. In this work, we report the preparation and characterization of novel vinyl polysiloxane getters. Starting from a methyl vinyl silicone oil prepared by ring-opening polymerization, polysiloxane getters in versatile forms that are adaptable to various environments are prepared by adding Pd/C and then curing. Combined with the thermal and radiation stability of polysiloxane, not only will these new getters be applicable in future applications in the electronic and nuclear industries as hydrogen scavengers, they also serve as platform for further development of polymer getters with superior properties.
Forest ecosystems play an important role in regulating global temperatures through their capability to take up and store CO2 from the atmosphere, but the magnitude and sustainability of this carbon ...(C) sink is critically dependent on the availability of nutrients, particularly nitrogen (N). However, the extent to which the absolute amount of N or modifications in plant and soil C:N ratios controls long-term forest carbon sequestration (Cseq) remains uncertain. To assess this, we analyzed the results of 135 global field studies that investigated the dynamics of C and N availability during forest succession. The results showed that the accumulation of C and N in plant (including above- and below-ground vegetation) and litter pools decreased with forest age and approached an equilibrium value in the latter stages of stand development. Plant and litter C:N ratios increased during the first 10-20 years and remained relatively stable thereafter. The analysis further showed that the relative importance of a change in the total amount of N or modifications in the C:N ratio, to increases in Cseq, varied with forest age. Whilst the relative importance of a change in the total amount of N increased with forest age, the relative importance of a varied C:N stoichiometry decreased with forest age. Overall, a change in the total amount of N was the more important factor contributing to C storage during forest stand development and the C stored in vegetation dominated the total ecosystem C pool. These results show that ecosystem N availability is a key factor supporting long-term forest Cseq during forest succession. As most of the C is found in above-ground vegetation, this pool is particularly susceptible to abiotic or biotic factors and anthropogenically-related disturbances.
Growing evidence indicates that some grass species are more tolerant to various abiotic and biotic stresses than many crops. Zinc finger proteins play important roles in plant abiotic and biotic ...stresses. Although genes coding for these proteins have been cloned and identified in various plants, their function and underlying transcriptional mechanisms in the halophyte Zoysia japonica are barely known. In the present study, ZjZFN1 was isolated from Z. japonica using RACE method. Quantitative real time PCR results revealed that the expression of ZjZFN1 was much higher in leaf than in root and stem tissues, and induced by salt, cold or ABA treatment. The subcellular localization assay demonstrated that ZjZFN1 was localized to the nucleus. Expression of the ZjZFN1 in Arabidopsis thaliana improved seed germination and enhanced plant adaption to salinity stress with improved percentage of green cotyledons and growth status under salinity stress. Physiological and transcriptional analyses suggested that ZjZFN1 might, at least in part, influence reactive oxygen species accumulation and regulate the transcription of salinity responsive genes. Furthermore, RNA-sequencing analysis of ZjZFN1-overexpressing plants revealed that ZjZFN1 may serve as a transcriptional activator in the regulation of stress responsive pathways, including phenylalanine metabolism, α-linolenic acid metabolism and phenylpropanoid biosynthesis pathways. Taken together, these results provide evidence that ZjZFN1 is a potential key player in plants' tolerance to salt stress, and it could be a valuable gene in Z. japonica breeding projects.
The chloroplast genomes of angiosperms usually have a stable circular quadripartite structure that exhibits high consistency in genome size and gene order. As one of the most diverse genera of ...angiosperms,
is of great value for the study of evolutionary relationships and speciation within its genus, but the study of the structure of its chloroplast genome is limited due to its highly expanded and restructured genome with a large number of repeats. In this study, we provided a more detailed account of the chloroplast genomes of
using a hybrid assembly of second- and third-generation sequencing and examined structural variation within this genus. The study revealed that chloroplast genomes of four
species are significantly longer than that of most angiosperms and are characterized by high sequence rearrangement rates, low GC content and gene density, and increased repetitive sequences. The location of chloroplast genome structural variation in the species of
studied is closely related to the positions of long repeat sequences; this genus provides a typical example of chloroplast structural variation and expansion caused by long repeats. Phylogenetic relationships constructed based on the chloroplast protein-coding genes support the latest taxonomic system of
, while revealing that structural variation in the chloroplast genome of
may have some phylogenetic significance. Moreover, this study demonstrated a hybrid assembly approach based on long and short reads to analyze complex chloroplast genome assembly and also provided an important reference for the analysis of structural rearrangements of chloroplast genomes in other taxa.
Carex L. is one of the largest genera in the Cyperaceae family and an important vascular plant in the ecosystem. However, the genetic background of Carex is complex and the classification is not ...clear. In order to investigate the gene function annotation of Carex, RNA-sequencing analysis was performed. Simple sequence repeats (SSRs) were generated based on the Illumina data and then were utilized to investigate the genetic characteristics of the 79 Carex germplasms.
In this study, 36,403 unigenes with a total length of 41,724,615 bp were obtained and annotated based on GO, KOG, KEGG, NR databases. The results provide a theoretical basis for gene function exploration. Out of 8776 SSRs, 96 pairs of primers were randomly selected. One hundred eighty polymorphic bands were amplified with a polymorphism rate of 100% based on 42 pairs of primers with higher polymorphism levels. The average band number was 4.3 per primer, the average distance value was 0.548, and the polymorphic information content was ranged from 0.133 to 0.494. The number of observed alleles (Na), effective alleles (Ne), Nei's (1973) gene diversity (H), and the Shannon information index (I) were 2.000, 1.376, 0.243, and 0.391, respectively. NJ clustering divided into three groups and the accessions from New Zealand showed a similar genetic attribute and clustered into one group. UPGMA and PCoA analysis also revealed the same result. The analysis of molecular variance (AMOVA) revealed a superior genetic diversity within accessions than between accessions based on geographic origin cluster and NJ cluster. What's more, the fingerprints of 79 Carex species are established in this study. Different combinations of primer pairs can be used to identify multiple Carex at one time, which overcomes the difficulties of traditional identification methods.
The transcriptomic analysis shed new light on the function categories from the annotated genes and will facilitate future gene functional studies. The genetic characteristics analysis indicated that gene flow was extensive among 79 Carex species. These markers can be used to investigate the evolutionary history of Carex and related species, as well as to serve as a guide in future breeding projects.
Pheophytinase (PPH), the phytol hydrolase, plays important roles in chlorophyll degradation. Nevertheless, little attention has been paid to the PPHs in warm-season grass species; neither its ...detailed function in photosynthesis has been systematically explored to date. In this study, we isolated
from
, an excellent warm-season turfgrass species. Quantitative real-time PCR analysis and promoter activity characterization revealed that the expression of
could be induced by senescence, ABA, and dark induction. Subcellular localization observation proved that ZjPPH was localized in the chloroplasts. Overexpression of
accelerated the chlorophyll degradation and rescued the stay-green phenotype of the Arabidopsis
mutant. Moreover,
promoted senescence with the accumulation of ABA and soluble sugar contents, as well as the increased transcriptional level of
and
. Transmission electron microscopy investigation revealed that
caused the decomposition of chloroplasts ultrastructure in stable transformed Arabidopsis. Furthermore, chlorophyll
fluorescence transient measurement analysis suggested that
suppressed photosynthesis efficiency by mainly suppressing both photosystem II (PSII) and photosystem I (PSI). In conclusion,
plays an important role in chlorophyll degradation and senescence. It could be a valuable target for genetic editing to cultivate new germplasms with stay-green performance and improved photosynthetic efficiency.
The halophyte
Karelinia caspia
has not only fodder and medical value but also can remediate saline-alkali soils. Our previous study showed that salt-secreting by salt glands is one of main adaptive ...strategies of
K. caspia
under high salinity. However, ROS scavenging, ion homeostasis, and photosynthetic characteristics responses to high salinity remain unclear in
K. caspia
. Here, physio-biochemical responses and gene expression associated with ROS scavenging and ions transport were tested in
K. caspia
subjected to 100–400 mM NaCl for 7 days. Results showed that both antioxidant enzymes (SOD, APX) activities and non-enzymatic antioxidants (chlorogenic acid, α-tocopherol, flavonoids, polyamines) contents were significantly enhanced, accompanied by up-regulating the related enzyme and non-enzymatic antioxidant synthesis gene (
KcCu/Zn-SOD
,
KcAPX6
,
KcHCT, KcHPT1
,
Kcγ-TMT, KcF3H
,
KcSAMS
and
KcSMS
) expression with increasing concentrations of NaCl. These responses are beneficial for removing excess ROS to maintain a stable level of H
2
O
2
and O
2
−
without lipid peroxidation in the
K. caspia
response to high salt. Meanwhile, up-regulating expression of
KcSOS1/2/3, KcNHX1,
and
KcAVP
was linked to Na
+
compartmentalization into vacuoles or excretion through salt glands in
K. caspia
. Notably, salt can improve the function of PSII that facilitate net photosynthetic rates, which is helpful to growing normally in high saline. Overall, the findings suggested that ROS scavenging systems and Na
+
/K
+
transport synergistically contributed to redox equilibrium, ion homeostasis, and the enhancement of PSII function, thereby conferring high salt tolerance.
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