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opencc-zeroDec 2018View details →

Data from: Impacts of mixed-grazing on root biomass and belowground net primary production in a temperate desert steppe

The impacts of large herbivores on plant communities differ depending on the plants and the herbivores. Few studies have explored how herbivores influence root biomass. Root growth of vegetation was studied in the field with four treatments: sheep grazing alone (SG), cattle grazing alone (CG), mixed grazing with cattle and sheep (MG) and no grazing (CK). Live and total root biomasses were measured using the root ingrowth core and the drilling core, respectively. After 2 years of grazing, total root biomass showed a decreasing trend while live root biomass increased with time during the growing seasons. Belowground net primary production (BNPP) among the treatments varied from 166±32 to 501±88 g.m-2 and root turnover rates (RTR) varied from 0.25±0.05 to 0.70±0.11 year-1. SG had the greatest BNPP and RTR, while the CG had the smallest BNPP and RTR. BNPP and RTR of the MG treatment were between those of the CG and SG treatments. BNPP and RTR of the CK were similar to MG treatment. Compared with other treatments, CG had a greater impact on dominant tall grasses species in communities. SG could decrease community diversity. MG eliminated the disadvantages of single-species grazing and was beneficial to community diversity and stability.

opencc-zeroDec 2015View details →

Data from: Effects of species diversity on fine root productivity increase with stand development and associated mechanisms in a boreal forest

There is a growing interest in understanding the relationship between diversity and below-ground productivity due to the critical contribution of below-ground systems to overall terrestrial productivity. Yet, the temporal (seasonal and developmental) changes in diversity effects on below-ground productivity and their underlying mechanisms remain unclear. We hypothesized that (i) diversity effects on fine root productivity increase with stand development, and (ii) increased diversity effects associated with stand development result from augmented horizontal soil space utilization, increased forest floor depth for rooting, enhanced effects in nutrient-poor soil layers and/or foraging towards high nutrient availability. We investigated the effects of tree species diversity on fine root productivity by sampling 18 stands dominated by single species and their mixtures in post-fire boreal forests of two stand ages (8 and 34 years following stand-replacing fire). Species evenness was significantly higher in species mixtures than in single-species-dominated stands at both age classes, while species richness did not differ across stand types and age classes. We found that the annual fine root production was higher in mixtures than the mean of single-species-dominated stands in both stand ages, with a significantly higher magnitude of effects in the 34-year-old than 8-year-old stands. Mixtures had higher horizontal soil volume filling than single-species-dominated stands with a more pronounced increase in the 34-year-old than 8-year-old stands. Compared with the 8-year-old stands, the 34-year-old stands had increased forest floor depth and greater overyielding with soil depth, and their fine root productivity was more responsive to the vertical variation in soil phosphorus concentrations among soil layers. Synthesis. Our results provide evidence for increasing positive diversity effects on fine root productivity with stand development in heterogeneous natural forests. Moreover, our results indicate that the increased positive diversity effects with stand development was the result of multiple mechanisms, including higher horizontal soil volume filling, a thicker forest floor layer for rooting, a higher magnitude of complementarity in nutrient-poor deep soil layers and stronger nutrient foraging towards soil layers with high nutrient concentrations in older than younger stands.

opencc-zeroJun 2021View details →

Nitrogen fixation and crop productivity enhancements codriven by intercrop root exudates and key rhizosphere bacteria

1. Crop diversity management is widely used to increase agricultural productivity and sustainability. Recent studies have demonstrated that maize root exudates can drive interspecific facilitation to enhance N2 fixation of bean in intercropping systems. However, the mechanisms of N2 fixation enhancement stimulated by root exudates in the intercropping systems remain unclear. 2. Four experiments were designed to provide a progressively deeper understanding of how root exudates stimulate microbial-mediated N2 fixation. First, the effects of faba bean/maize intercropping on yields and soil microbial communities were determined in a field experiment. Second, root-derived interspecific facilitation was evaluated using a root partitioning approach. Third, the key microbial taxa in the faba bean rhizosphere were traced using 13C-labeled maize root exudates. Fourth, the codriven mechanism of maize root exudates and microorganisms in the faba bean rhizosphere were explored. 3. Faba bean/maize intercropping with maize residue return increased the yields of faba bean (26%), maize (27%), and broccoli (9.1%) compared to that under monocropping. Nodulin-like 4 (NODL4), chalcone-flavanone isomerase (CFI), and early nodulin-like (ENODL2) gene expression in faba bean roots intercropped with maize increased by 1.5-2.3-fold compared to that observed under monoculture. More than half of the N2 fixation of faba bean increase under intercropping was due to interactions with microorganisms. Nine key bacterial genera in the faba bean rhizosphere were identified by 13C-DNA based stable isotope probing analysis. Among them Agromyces, Arthrobacter, Bacillus, Lysobacter, and Paenibacillus directly fix N2, while Gemmatimonas, Heliobacillus, Natronocella, and Sorangium increase the N2 fixation capacity of Azotobacter by providing additional carbon sources. These key bacteria triggered by maize root exudates played an important role in the rhizosphere facilitation of intercropping. 4. Synthesis and applications. We demonstrated a novel root-root facilitation of N2 fixation and increased crop yields codriven by root exudates and rhizosphere bacteria under faba bean/maize intercropping, and nine key bacteria associated with this process were identified by 13C-DNA based stable isotope probing. We recommend the adoption and optimization of intercropping systems with residue return to reduce the shortcomings of continuous cropping and to increase the sustainability of crop <a>production</a>.

opencc-zeroDec 2017View details →

Data from: Litter removal in a tropical rain forest reduces fine root biomass and production but litter addition has few effects

Many old-growth lowland tropical rain forests are potentially nutrient limited, and it has long been thought that many such forests maintain growth by recycling nutrients from decomposing litter. We investigated this by continuously removing (for ten years) freshly fallen litter from five (45 m x 45 m) plots, adding it to five other plots, there were five controls. From monthly measures over one year we show that litter removal caused lower: fine root (≤2 mm diameter) standing mass, fine root standing length, fine root length production and fine root length survivorship. Litter addition did not significantly change fine root mass or length or production. Nutrient concentrations in fine roots in litter removal plots were lower than those in controls for nitrogen (N), calcium (Ca) and magnesium (Mg), concentrations in fine roots in litter addition plots were higher for N and Ca. Chronic litter removal has resulted in reduced forest growth due to lack of nutrients, probably nitrogen. Conversely, long-term litter addition has had fewer effects.

opencc-by-4.0Nov 2024View details →

Data products from "An 85-year record of glacier change and impacts on future projections for Kennicott and Root Glaciers, Alaska"

DEMs, orthophotos, glacier outlines, historical velocity, model outputs, and ice-penetrating radar data from "An 85-year record of glacier change and impacts on future projections for Kennicott and Root Glaciers, Alaska". File structure is shown in the readme file.

Fig. 4. A in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 4. A. Growth of wild type root cultures on different Trp derivatives as compared to growth on MS medium only. B. Correlation of the relative growth and the production of different Cl-Trp compounds.

Fig. 3. A in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 3. A. All transgenic root lines were analyzed by the following experiments and the data are presented for selected lines transformed with the pMDC32+2xCaMV35S:pyrH:nosT construct (pyrH = 5-Cl-Trp-forming). Transformation of roots with A. rhizogenes was verified using gDNA and cDNA for a successful insertion and expression, respectively. A. Upper panel: Amplified rolB (423 bp) and rolC (626 bp) for three different lines (lanes 1–3) using gDNA. The virG gene (350 bp) was only detectable in the positive control (Ri-plasmid of A. rhizogenes) (lane +) "-" denotes a negative PCR control. Lower panel: Integration of full length hal gene (ca. 1.5 kb) using gDNA. Expression of full length hal gene (ca. 1.5 kb) using cDNA. "+": positive control (plasmid containing pyrH or the other hal genes), "-": negative PCR control, g: gDNA wild type, c: cDNA wild type, 1–3: three independent transgenic root culture lines with the pMDC32+2xCaMV35S:pyrH:nosT construct, "1-"-"3-": RT negative controls (containing no DNA). B. Western blot with the purified His-tagged proteins: 1: PyrH, 2: ThaI, 3: PrnA, a: PyrH synthesized in E. coli, b: positive control ThaI synthesized in E. coli, c: positive control PrnA synthesized in E. coli. Wild type protein as control did not show any signal (data not shown). C. Enzyme assay with the purified halogenase PyrH. The positive control is PyrH protein synthesized in bacteria. The negative control is purified protein from wild type root cultures. Since only for PyrH enzyme activity could be detected, the data for the other halogenases are shown in the supplement (Fig. S1). D. Production of chlorinated tryptophan (Cl-Trp) and indole-3-acetonitrile (ClIAN) in transgenic root lines. For each halogenase construct five independent lines were tested. Results for 5 lines per halogenase type with and without Histag are indicated by the numbers of lines with the respective metabolites. The detailed results for all individual lines are shown in the supplement (Fig. S2).

Fig. 6. A in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 6. A. Confirmation of i) that the regenerated plants contain still the rol genes and ii) the integration of the hal gene into the genome and its transcription into cDNA (1: regenerated plants from wild type root cultures; 2: BrRP-pyrHHIS.6; 3: A. rhizogenes plasmid; 4: negative PCR control; 5: positive control - hal amplification from plasmid; a: cDNA, b: cDNA "no template control; genomic DNA. B. Western blot of His-tagged halogenase (PyrH, Thal, PrnA: purified enzymes from overexpressing E. coli strain as positive controls; BrRP-HR = WT, regenerated plants from wild type root cultures; BrRP-S: regenerated plants from Chinese cabbage seedlings; BrRP-pyrH, -thal, -prnA: regenerated plants from transgenic roots.). Always two different dilutions were applied. The gel strips were from the same gel, but due to large parts with samples without an immunosignal, the respective areas were cut out and are presented here. C. Relative amounts of chlorinated metabolites in the regenerated plants.

Fig. 2 in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 2. Expected indole metabolites and their interconversion (in black) that could be derived from tryptophan via the indole glucosinolate/indole phytoalexin pathway. It is indicated (in grey) that there are alternative pathways to IAA. The possible induction (dashed arrows) of chlorinated metabolites by abiotic and biotic stress factors, the latter also via the signaling molecules salicylic acid and jasmonic acid, is shown.

Fig. 1 in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 1. Experimental scheme showing the different types of plant materials generated. A. Mature wild type plants/seedlings; B. Wild type and transgenic root cultures; C. Regenerated sterile plants from wild type seedlings; D. Regenerated sterile plants from wild type and transgenic root cultures; E. Adult plants in soil from wild type cultures; F. Adult plants in soil from transgenic root cultures.

Fig. 5 in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 5. Left: Average number of regenerated shoots for 25 Brassica rapa "hairy root" lines (denoted therefore as BrHR ….) on 3 media compositions (n = 24). Medium A: GB5 medium containing 8 g l−1 phytoagar, 20 g l−1 sucrose and 10 mg l−1 6-BAP. Medium B: MS medium containing 8 g l−1 phytoagar, 30 g l−1 sucrose, 4 mg l−1 6-BAP, 4 mg l−1 AgNO3 and 3 mg l−1 NAA. Medium C: MS medium containing 8 g l−1 phytoagar, 30 g l−1 sucrose, 4 mg l−1 6-BAP, 4 mg l−1 AgNO3 and 0.5 mg l−1 NAA. Right: Shoot regeneration from B. rapa root cultures. Pieces from these root cultures were cut into pieces of approximately 1 cm2 and placed on semisolid agar (A). Regeneration of shoots was visible after 4 weeks of cultivation (B). Regenerated shoots were separated and transferred to fresh media (C). Shoot growth was often accompanied by growth of transformed/transgenic roots (D). Shoots of adequate biomass quality were subcultivated (E). Some B. rapa lines displayed a shortened life cycle after regeneration and began flowering (F).

Fig. 7 in Hairy root transformation of Brassica rapa with bacterial halogenase genes and regeneration to adult plants to modify production of indolic compounds

Fig. 7. Comparison of phenotypic traits for three groups of Brassica rapa grown in the greenhouse. WT – shoots from wild type plants grown from seeds (photo A); REG – regenerated shoots originated from transformed root cultures (photo B); HLR – regenerated shoots originated from transgenic roots transfected with bacterial hal genes (photo C). Significant differences between treatments are labeled as follows: 0 '***' 0.001 '**' 0.01 '*' 0.05 (with n = minimum of 20 individually potted plants). Leaves of in vitro shoots originated from seeds (left) or regenerated from root cultures (right) are shown.

opennotspecifiedNov 2020View details →

Fig. 4. Pearson correlation values for glucosinolate hydrolytic products. Panel A in Glucosinolate catabolism during postharvest drying determines the ratio of bioactive macamides to deaminated benzenoids in Lepidium meyenii (maca) root flour

Fig. 4. Pearson correlation values for glucosinolate hydrolytic products. Panel A shows the correlation of metabolites for the early stage of drying, where reactions are caused by direct damage to the tissue by shredding. Panel B shows the correlation between intermediaries as a result of the late stage tissue dehydration. BCOOR- 2, BCHO-2 and BCOOH-2 shown in panel B correspond to data points in Fig. 5 shown as part of the red solid line while BCOOR (8a), BCHO (5) and BCOOH (8) in panel A correspond to the early stage in the figure shown in solid black lines. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

publicSep 2017View details →

Data from: Effects of species diversity on fine root productivity increase with stand development and associated mechanisms in a boreal forest

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