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opencc-zeroDec 2014View details →

Data from: Increased susceptibility to fungal disease accompanies adaptation to drought in Brassica rapa

Recent studies have demonstrated adaptive evolutionary responses to climate change, but little is known about how these responses may influence ecological interactions with other organisms, including natural enemies. We used a resurrection experiment in the greenhouse to examine the effect of evolutionary responses to drought on the susceptibility of Brassica rapa plants to a fungal pathogen, Alternaria brassicae. In agreement with previous studies in this population, we found an evolutionary shift to earlier flowering post-drought, which was previously shown to be adaptive. Here we report the novel finding that post-drought descendant plants were also more susceptible to disease, indicating a rapid evolutionary shift to increased susceptibility. This was accompanied by an evolutionary shift to increased specific leaf area (thinner leaves) following drought. We found that flowering time and disease susceptibility displayed plastic responses to experimental drought treatments, but that this plasticity did not match the direction of evolution, indicating that plastic and evolutionary responses to changes in climate can be opposed. The observed evolutionary shift to increased disease susceptibility accompanying adaptation to drought provides evidence that even if populations can rapidly adapt in response to climate change, evolution in other traits may have ecological effects that could make species more vulnerable.

opencc-zeroOct 2021View details →

Genotyping-by-Sequencing data of weedy and domesticated Brassica rapa L.

The study of domestication contributes to our knowledge of evolution and crop genetic resources. Human selection has shaped wild Brassica rapa into diverse turnip, leafy, and oilseed crops. Despite its worldwide economic importance and potential as a model for understanding diversification under domestication, insights into the number of domestication events and initial crop(s) domesticated in B. rapa have been limited due to a lack of clarity about the wild or feral status of conspecific non-crop relatives. To address this gap and reconstruct the domestication history of B. rapa, we analyzed 68,468 genotyping-by-sequencing-derived SNPs for 416 samples in the largest diversity panel of domesticated and weedy B. rapa to date. To further understand the center of origin, we modeled the potential range of wild B. rapa during the mid-Holocene. Our analyses of genetic diversity across B. rapa morphotypes suggest that non-crop samples from the Caucasus, Siberia, and Italy may be truly wild, while those occurring in the Americas and much of Europe are feral. Clustering, tree-based analyses, and parameterized demographic inference further indicate that turnips were likely the first crop type domesticated, from which leafy types in East Asia and Europe were selected from distinct lineages. These findings clarify the domestication history and nature of wild crop genetic resources for B. rapa, which provides the first step toward investigating cases of possible parallel selection, the domestication and feralization syndrome, and novel germplasm for Brassica crop improvement.

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.

publicOct 2021View details →

Genotyping-by-Sequencing data of weedy and domesticated Brassica rapa L.

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publicOct 2018View details →

Data from: Temporal population genetic structure in the pollen pool for flowering time: a field experiment with Brassica rapa (Brassicaceae)

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