Expansion of mass-flowering crops leads to transient pollinator dilution and reduced wild plant pollination.
- Proceedings. Biological sciences / The Royal Society
- Published almost 10 years ago
Agricultural land use results in direct biodiversity decline through loss of natural habitat, but may also cause indirect cross-habitat effects on conservation areas. We conducted three landscape-scale field studies on 67 sites to test the hypothesis that mass flowering of oilseed rape (Brassica napus) results in a transient dilution of bees in crop fields, and in increased competition between crop plants and grassland plants for pollinators. Abundances of bumble-bees, which are the main pollinators of the grassland plant Primula veris, but also pollinate oilseed rape (OSR), decreased with increasing amount of OSR. This landscape-scale dilution affected bumble-bee abundances strongly in OSR fields and marginally in grasslands, where bumble-bee abundances were generally low at the time of Primula flowering. Seed set of Primula veris, which flowers during OSR bloom, was reduced by 20 per cent when the amount of OSR within 1 km radius increased from 0 to 15 per cent. Hence, the current expansion of bee-attractive biofuel crops results in transient dilution of crop pollinators, which means an increased competition for pollinators between crops and wild plants. In conclusion, mass-flowering crops potentially threaten fitness of concurrently flowering wild plants in conservation areas, despite the fact that, in the long run, mass-flowering crops can enhance abundances of generalist pollinators and their pollination service.
The regulation of lipid synthesis in oil seeds is still not fully understood. Oilseed rape is the third most productive vegetable oil crop on the global market. Therefore, increasing our understanding of lipid accumulation in oilseed rape seeds is of great economic, as well as intellectual, importance. Matrix-assisted laser/desorption ionisation - mass spectrometry imaging (MALDI-MSI) is a technique that allows the mapping of metabolites directly onto intact biological tissues, giving a spatial context to metabolism. We have used MADLI-MSI to study the spatial distribution of two major lipid species, triacylglycerols (TAGs) and phosphatidylcholines (PCs). A dramatic, heterogeneous landscape of molecular species was revealed, demonstrating significantly different lipid compositions between the various seed tissues. The embryonic axis was particularly enriched in lipid species containing palmitate, while the seed coat/aleurone layer accumulated vaccenic, linoleic and α-linoleic acids. Furthermore, the lipid composition of the inner and outer cotyledons differed to each other, a remarkable discovery given the supposed identical functionality of these two tissues. TAG and PC molecular species distribution was analysed through a developmental time series covering early seed lipid accumulation to the end of lipid accumulation. The spatial patterning of lipid molecular species did not vary much during seed development, although there were exceptions. Data gathered using MALDI-MSI was verified through gas chromatography analysis of dissected seeds. The distinct lipid distribution profiles observed implies differential regulation of lipid metabolism between the different seed tissues. Further understanding of this differential regulation will enhance efforts to improve oilseed rape productivity and quality.
Cruciferous vegetables intake and the risk of colorectal cancer: a meta-analysis of observational studies.
- Annals of oncology : official journal of the European Society for Medical Oncology / ESMO
- Published about 8 years ago
BackgroundEpidemiological studies have reported inconsistent associations between cruciferous vegetable (CV) intake and colorectal cancer (CRC) risk. To our knowledge, a comprehensive and quantitative assessment of the association between CV intake and CRC has not been reported.MethodsRelevant articles were identified by searching MEDLINE. We pooled the relative risks (RR) from individual studies using a random-effect model and carried out heterogeneity and publication bias analyses.ResultsTwenty-four case-control and 11 prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (RR: 0.82; 95% confidence interval 0.75-0.90) intake and CRC risk. Specific analysis for cabbage and broccoli yielded similar result. When separately analyzed, case-control studies of CV intake yield similar results, and the results from the prospective studies showed borderline statistical significance. Moreover, significant inverse associations were also observed in colon cancer and its distal subsite both among prospective and case-control studies.ConclusionsFindings from this meta-analysis provide evidence that high intake of CV was inversely associated with the risk of CRC and colon cancer in humans. Further analysis on other specific CV, food preparation methods, stratified results by anatomic cancer site, and subsite of colon cancer should be extended in future study.
The paper presents a real-time PCR method allowing the simultaneous detection of traces of black mustard (Brassica nigra) and brown mustard (Brassica juncea) in food. The primers and the probe target the B. nigra partial RT gene for reverse transcriptase from gypsy-like retroelement 13G42-26. The real-time PCR method does not show any cross-reactivity with other Brassicaceae species with the exception of white mustard. Low cross-reactivities with cinnamon, cumin, fenugreek, ginger, rye and turmeric can be ignored because in common mustard containing foodstuffs these biological species are present in very low amounts. By analysing serially diluted DNA extracts from black and brown mustard, the DNA of both mustard species could be detected down to 0.1 pg. With 10 ng DNA per PCR tube the real-time PCR method allows the detection of 5 ppm black and brown mustard in brewed sausages.
Ogura-CMS in Chinese cabbage (Brassica rapa ssp. pekinensis) causes delayed expression of many nuclear genes
- Plant science : an international journal of experimental plant biology
- Published about 8 years ago
We investigated the mechanism regulating cytoplasmic male sterility (CMS) in Brassica rapa ssp. pekinensis using floral bud transcriptome analyses of Ogura-CMS Chinese cabbage and its maintainer line in B. rapa 300-K oligomeric probe (Br300K) microarrays. Ogura-CMS Chinese cabbage produced few and infertile pollen grains on indehiscent anthers. Compared to the maintainer line, CMS plants had shorter filaments and plant growth, and delayed flowering and pollen development. In microarray analysis, 4646 genes showed different expression, depending on floral bud size, between Ogura-CMS and its maintainer line. We found 108 and 62 genes specifically expressed in Ogura-CMS and its maintainer line, respectively. Ogura-CMS line-specific genes included stress-related, redox-related, and B. rapa novel genes. In the maintainer line, genes related to pollen coat and germination were specifically expressed in floral buds longer than 3mm, suggesting insufficient expression of these genes in Ogura-CMS is directly related to dysfunctional pollen. In addition, many nuclear genes associated with auxin response, ATP synthesis, pollen development and stress response had delayed expression in Ogura-CMS plants compared to the maintainer line, which is consistent with the delay in growth and development of Ogura-CMS plants. Delayed expression may reduce pollen grain production and/or cause sterility, implying that mitochondrial, retrograde signaling delays nuclear gene expression.
Plants emit various volatile organic compounds (VOCs) upon herbivore attack. These VOC emissions often show temporal dynamics which may influence the behavior of natural enemies using these volatiles as cues. This study analyzes on-line VOC emissions by roots of Brassica nigra plants under attack by cabbage root fly larvae, Delia radicum. Root emitted VOCs were detected using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) and Gas Chromatography-Mass Spectrometry (GC-MS). These analyses showed that several sulfur containing compounds, such as methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and glucosinolate breakdown products, such as thiocyanates (TC) and isothiocyanates (ITC), were emitted by the roots in response to infestation. The emissions were subdivided into early responses, emerging within 1-6h after infestation, and late responses, evolving only after 6-12h. The marker for rapid responses was detected at m/z 60. The ion detected at m/z 60 was identified as thiocyanic acid, which is also a prominent fragment in some TC or ITC spectra. The emission of m/z 60 stopped when the larvae had pupated, which makes it an excellent indicator for actively feeding larvae. Methanethiol, DMS and DMDS levels increased much later in infested roots, indicating that activation of enzymes or genes involved in the production of these compounds may be required. Earlier studies have shown that both early and late responses can play a role in tritrophic interactions associated with Brassica species. Moreover, the identification of these root induced responses will help to design non-invasive analytical procedures to assess root infestations.
Clubroot disease is one of the major diseases affecting Brassicaceae crops, and a number of these crops grown commercially, such as Chinese cabbage (Brassica rapa L. ssp. pekinensis), are known to be highly susceptible to clubroot disease. To provide protection from this disease, plant breeders have introduced genes for resistance to clubroot from the European turnip into susceptible lines. The CRa gene confers specific resistance to the clubroot pathogen Plasmodiophora brassicae isolate M85. Fine mapping of the CRa locus using synteny to the Arabidopsis thaliana genome and partial genome sequences of B. rapa revealed a candidate gene encoding a TIR-NBS-LRR protein. Several structural differences in this candidate gene were found between susceptible and resistant lines, and CRa expression was observed only in the resistant line. Four mutant lines lacking clubroot resistance were obtained by the UV irradiation of pollen from a resistant line, and all of these mutant lines carried independent mutations in the candidate TIR-NBS-LRR gene. This genetic and molecular evidence strongly suggests that the identified gene is CRa. This is the first report on the molecular characterization of a clubroot Resistance gene in Brassicaceae and of the disease resistance gene in B. rapa.
Herbivore-induced plant volatiles (HIPVs) serve as specific cues to higher trophic levels. Novel, exotic herbivores entering native foodwebs may disrupt the infochemical network as a result of changes in HIPV profiles. Here, we analysed HIPV blends of native Brassica rapa plants infested with one of 10 herbivore species with different coexistence histories, diet breadths and feeding modes. Partial least squares (PLS) models were fitted to assess whether HIPV blends emitted by Dutch B. rapa differ between native and exotic herbivores, between specialists and generalists, and between piercing-sucking and chewing herbivores. These models were used to predict the status of two additional herbivores. We found that HIPV blends predicted the evolutionary history, diet breadth and feeding mode of the herbivore with an accuracy of 80% or higher. Based on the HIPVs, the PLS models reliably predicted that Trichoplusia ni and Spodoptera exigua are perceived as exotic, leaf-chewing generalists by Dutch B. rapa plants. These results indicate that there are consistent and predictable differences in HIPV blends depending on global herbivore characteristics, including coexistence history. Consequently, native organisms may be able to rapidly adapt to potentially disruptive effects of exotic herbivores on the infochemical network.
Nitrogen use efficiency (NUE) is relatively low in oilseed rape (Brassica napus L.) due to weak nitrogen remobilization during leaf senescence. Monitoring the kinetics of water distribution associated with the re-organization of cell structures would therefore be valuable to improve characterization of nutrient recycling in leaf tissues and the associated senescence processes. In this study, NMR Relaxometry was used to describe water distribution and status at the cellular level in different leaf ranks of well-watered plants. It was shown to be able to detect slight variations in the evolution of senescence. The NMR results were linked to physiological characterization of the leaves and to light and electron micrographs. A relationship between cell hydration and leaf senescence was revealed and associated with changes in the NMR signal. The relative intensities and the transverse relaxation times of the NMR signal components associated with vacuole water were positively correlated with senescence, describing water uptake and vacuole and cell enlargement. Moreover, the relative intensity of the NMR signal that we assigned to the chloroplast water decreased during the senescence process, in agreement with the decrease in relative chloroplast volume estimated from micrographs. The results are discussed on the basis of water flux occurring at the cellular level during senescence. One of the main applications of this study would be for plant phenotyping, especially for plants under environmental stress such as nitrogen starvation.
To our knowledge, there is little research on metabolic characteristics of the protein in newly developed yellow-type and brown type of Canola meal and canola presscake. The objectives of this study were to (1) identify differences in the metabolic characteristics of the protein among yellow-seeded (Brassica juncea) and brown-seeded (Brassica napus) canola meal and brown-seeded (Brassica napus) canola presscake modeled for dairy cattle, (2) determine the extent of ruminal and intestinal digestion and absorption of the protein, (3) determine feed milk value and (4) compare three evaluation systems in modeling nutrient supply to dairy cattle, namely, the DVE/OEB system (DVE = truly absorbed protein in the small intestine; OEB = degraded protein balance), the National Research Council (NRC) 2001 model and the PDI system (Protein truly Digestible in the small Intestine). Comparison was made in terms of 1) ruminally synthesised microbial protein, 2) truly absorbed protein in the small intestine, 3) endogenous protein; 4) total metabolizable protein; and 5) degraded protein balance. The results showed that there were significant differences in the truly absorbed protein supply, protein degraded balance and feed milk value (P < 0.05) among the different types of canola meal. Yellow-seeded canola meal had significantly higher (P < 0.05) intestinal digestibility of rumen undegraded crude protein (%dRUP) than brown-seeded canola meal and presscake (%dRUP: 90 vs. 75 and 60%, respectively). Yellow-seeded canola meal also had higher (P < 0.05) total metabolizable protein predicted by all three models (DVE: 312 vs. 192 and 128 g/kg DM; MP: 287 vs. 193 and 168 g/kg DM, and PDIA: 264 vs. 168 and 137 g/kg DM, respectively), lower (P<0.05) degraded protein balance (OEB: 84 vs. 104 and 102 g/kg DM; DPB: 49 vs. 60 and 57 g/kg DM, respectively) and higher (P < 0.05) feed milk value (6.3 vs. 3.9 and 2.6 kg milk/kg feed, respectively) than the brown-seeded canola meal and presscake. In the model comparison, the supply of endogenous protein predicted by the DVE/OEB system was higher (P<0.05) than that predicted by NRC-2001 model. Moreover, a high proportion of the variability in truly absorbed rumen-undegraded feed protein in the small intestine and the total metabolisable protein predicted by DVE/OEB system was found that can be accounted for the equivalent parameters predicted by the NRC-2001 model. The truly absorbed rumen-synthesized microbial protein values predicted from PDI system were 19% lower than those predicted from the DVE/OEB system. Between the two latest mentioned models, no differences were detected in truly absorbed rumen-undegraded feed protein; microbial protein supply based on available energy and degraded protein balance. All the parameters predicted by the PDI system can be accounted for by the equivalent parameters predicted by the DVE/OEB system. When comparing PDI system and NRC-2001 model, the overall means for microbial protein supply based on energy and truly absorbed rumen-synthesized microbial protein were found to be lower than those predicted by the NRC-2001 model. Although the factors used in quantifying calculations as well as the evaluation system's concepts differ among each other, all three protein evaluation systems employed in this study, efficiently predict the potential nutrient supply to the animal from feedstuffs as affected by processing. In conclusion, the yellow-seeded canola meal provided highest total metabolizable protein and lowest degraded protein balance. KEYWORDS: Canola, Protein Metabolic Characteristics, Nutrient Modeling.