Christian Ulrichs

UV-B irradiation changes specifically the secondary metabolite profile in broccoli sprouts: induced signaling overlaps with defense response to biotic stressors.

Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth’s surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3–1 kJ m–2 d–1) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of non-volatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2×204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-B-mediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and up-regulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment.

Water stress and aphid feeding differentially influence metabolite composition in Arabidopsis thaliana (L.).

Little is known about how drought stress influences plant secondary metabolite accumulation and how this affects plant defense against different aphids. We therefore cultivated Arabidopsis thaliana (L.) plants under well-watered, drought, and water-logged conditions. Two aphid species were selected for this study: the generalist Myzus persicae (Sulzer) and the crucifer specialist Brevicoryne brassicae (L.). Metabolite concentrations in the phloem sap, which influence aphid growth, changed particularly under drought stress. Levels of sucrose and several amino acids, such as glutamic acid, proline, isoleucine, and lysine increased, while concentrations of 4-methoxyindol-3-ylmethyl glucosinolate decreased. M. persicae population growth was highest on plants under drought stress conditions. However, B. brassicae did not profit from improved phloem sap quality under drought stress and performed equally in all water treatments. Water stress and aphids generally had an opposite effect on the accumulation of secondary metabolites in the plant rosettes. Drought stress and water-logging led to increased aliphatic glucosinolate and flavonoid levels. Conversely, aphid feeding, especially of M. persicae, reduced levels of flavonoids and glucosinolates in the plants. Correspondingly, transcript levels of aliphatic biosynthetic genes decreased after feeding of both aphid species. Contrary to M. persicae, drought stress did not promote population growth of B. brassicae on these plants. The specialist aphid induced expression of CYP79B2, CYP79B3, and PAD3 with corresponding accumulation of indolyl glucosinolates and camalexin. This was distinct from M. persicae, which did not elicit similarly strong camalexin accumulation, which led to the hypothesis of a specific defense adaptations against the specialist aphid.

Influence of water stress on the glucosinolate profile of Brassica oleracea var. italica and the performance of Brevicoryne brassicae and Myzus persicae

Drought stress alters the chemical composition of plants, which can influence their tolerance to insect herbivory. To evaluate plant chemical responses to drought stress, broccoli, Brassica oleracea L. var. italica Plenck (Brassicaceae), was grown under well‐watered, drought, and water‐logged conditions. The glucosinolate (GS) levels and the performance of two aphid species, the specialist Brevicoryne brassicae (L.) and the generalist Myzus persicae (Sulzer) (both Hemiptera: Aphididae), in relation to water stress conditions were studied. High Performance Liquid Chromatography analysis showed that water stress changed the levels of GS in broccoli plants. Plants grown for 2 weeks under drought stress were significantly smaller and showed decreased levels of total GS when compared with GS contents of well‐watered plants, whereas water‐logged conditions led to a slight increase in the GS contents. A substantial decrease in indolyl GS was detected in water‐deficient plants, whereas aliphatic GS decreased slightly. Analysis of sugar levels in phloem sap of broccoli plants revealed that plants under water‐logged conditions contained the highest amounts of sugars followed by drought‐stressed and well‐watered plants. The two aphid species responded differently to water stress‐induced changes in their host plants. Significantly larger populations of M. persicae were recorded on plants with a limited water supply than on plants grown under well‐watered or water‐logged conditions. Brevicoryne brassicae was less affected by water stress, and similar population sizes were found on plants that were subject to different treatments. Analysis of covariance showed a significant effect of the plants’ water condition but no significant effect of GS content on the performance of M. persicae. However, the specialist B. brassicae remained unaffected by changes induced under water stress conditions.

Phyllotreta striolata flea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Significance Associations of plants and herbivores are regarded as the result of coevolution, which has produced an astonishing diversity of plant defenses and corresponding insect counteradaptations. We focus on the leaf beetle Phyllotreta striolata, which is adapted to the glucosinolate-myrosinase system present in its cruciferous host plants. We show that P. striolata adults not only selectively sequester intact glucosinolates from their host plants but also express their own myrosinase, a member of the β-glucosidase family capable of hydrolyzing glucosinolates to form toxic degradation products. Our results reveal the convergent evolution of a glucosinolate-myrosinase system in P. striolata that enables this herbivore to use glucosinolate hydrolysis products for its own purposes. The ability of a specialized herbivore to overcome the chemical defense of a particular plant taxon not only makes it accessible as a food source but may also provide metabolites to be exploited for communication or chemical defense. Phyllotreta flea beetles are adapted to crucifer plants (Brassicales) that are defended by the glucosinolate-myrosinase system, the so-called “mustard-oil bomb.” Tissue damage caused by insect feeding brings glucosinolates into contact with the plant enzyme myrosinase, which hydrolyzes them to form toxic compounds, such as isothiocyanates. However, we previously observed that Phyllotreta striolata beetles themselves produce volatile glucosinolate hydrolysis products. Here, we show that P. striolata adults selectively accumulate glucosinolates from their food plants to up to 1.75% of their body weight and express their own myrosinase. By combining proteomics and transcriptomics, a gene responsible for myrosinase activity in P. striolata was identified. The major substrates of the heterologously expressed myrosinase were aliphatic glucosinolates, which were hydrolyzed with at least fourfold higher efficiency than aromatic and indolic glucosinolates, and β-O-glucosides. The identified beetle myrosinase belongs to the glycoside hydrolase family 1 and has up to 76% sequence similarity to other β-glucosidases. Phylogenetic analyses suggest species-specific diversification of this gene family in insects and an independent evolution of the beetle myrosinase from other insect β-glucosidases.

Surface functionalized amorphous nanosilica and microsilica with nanopores as promising tools in biomedicine

Cellular interactions with engineered nanoparticles (NPs) are dependent on many properties, inherent to the nanoparticle (viz. size, shape, surface characteristics, degradation, agglomeration/dispersal, and charge, etc.). Modification of the surface reactivity via surface functionalization of the nanoparticles to be targeted seems to be important. Utilization of different surface functionalization methods of nanoparticles is an emerging field of basic and applied nanotechnology. It is well known that many disease-causing organisms induce host lipids and if deprived, their growth is inhibited in vivo. Amorphous nanosilica (ANS) and amorphous microsilica with nanopores (AMS) were prepared by a combination of wet chemistry and high-energy ball milling. Lipophilic moieties were attached to both ANS and AMS via chemical surface functionalization method. Lipophilic ANS and AMS were found to inhibit the growth of Bombyx mori nuclear polyhedrosis virus (BmNPV) and chicken malarial parasites via absorption of silkworm hemolymph and chicken serum lipids/lipoproteins, respectively, in vivo. Therefore, intelligent surface functionalization of NP is an important concept, and its application in curing chicken malaria and BmNPV is presented here. Surface functionalization method reported in this paper might serve as a valuable technology for treating many diseases where pathogens induce host lipid.

Male Phyllotreta striolata (F.) produce an aggregation pheromone: Identification of male-specific compounds and interaction with host plant volatiles

The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone. Volatiles emitted by feeding male P. striolata attracted males and females in the field. Headspace volatile analyses revealed that six sesquiterpenes were emitted specifically by feeding males. Only one of these, however, elicited an electrophysiological response from antennae of both sexes. A number of host plant volatiles, e.g., 1-hexanol, (Z)-3-hexen-1-ol, and the glucosinolate hydrolysis products allyl isothiocyanate (AITC), 3-butenyl isothiocyanate, and 4-pentenyl isothiocyanate also elicited clear responses from the antenna. The active male-specific compound was identified as (+)-(6R,7S)-himachala-9,11-diene by chiral stationary phase gas-chromatography with coupled mass spectrometry, and by comparison with reference samples from Abies nordmanniana, which is known to produce the corresponding enantiomer. The pheromone compound was synthesized starting from (–)-α-himachalene isolated from Cedrus atlantica. Under field conditions, the activity of the synthetic pheromone required concomitant presence of the host plant volatile allyl isothiocyanate. However, both synthetic (+)-(6R,7S)-himachala-9,11-diene alone and in combination with AITC were attractive in a two-choice laboratory assay devoid of other natural olfactory stimuli. We hypothesize that P. striolata adults respond to the pheromone only if specific host volatiles are present. In the same laboratory set up, more beetles were attracted by feeding males than by the synthetic stimuli. Thus, further research will be necessary to reveal the components of a more complex blend of host or male-produced semiochemicals that might enhance trap attractiveness in the field.

Factors Influencing the Variability of Antioxidative Phenolic Glycosides in Salix Species

Phenolic glycosides, especially the salicylates, are important secondary metabolites in the bark of willows (Salix spp.). Because of their anti-inflammatory, analgesic, and fever-reducing properties, they are of particular interest to society. Compared to the fabrication of synthetic salicylacetylic acid, the commercial production of willow bark extracts with adequate amounts of salicylate is very difficult due to several biological and technical reasons. Therefore, one of the objectives was to identify salicylate-rich clones from three species, Salix daphnoides , Salix purpurea , and Salix pentandra , with potentially high amounts of phenolic glycosides. Three hundred different Salix clones were collected, and the chemical profiles of their bark were analyzed by HPLC. Overall, S. daphnoides clones showed the highest phenolic glycoside contents, followed by S. purpurea and S. pentandra. Second, seasonal changes of secondary compounds in willow bark were analyzed to determine the optimal harvesting time. The phenolic glycoside levels decreased over the growing season, with highest contents detected during plant dormancy. The effects of different cultivation conditions were also examined, and none of these treatments were found to have a significant effect on the phenolic glycoside content in willow bark. Biomass accumulation in the clones with grass competition was significantly lower than in the other three treatments.

Single- versus Multiple-Pest Infestation Affects Differently the Biochemistry of Tomato (Solanum lycopersicum 'Ailsa Craig').

Tomato is susceptible to pest infestations by both spider mites and aphids. The effects of each individual pest on plants are known, whereas multiple-pest infestations have received little interest. We studied the effects of single- versus multiple-pest infestation by Tetranychus urticae and Myzus persicae on tomato biochemistry (Solanum lycopersicum) by combining a metabolomic approach and analyses of carotenoids using UHPLC-ToF-MS and volatiles using GC-MS. Plants responded differently to aphids and mites after 3 weeks of infestation, and a multiple infestation induced a specific metabolite composition in plants. In addition, we showed that volatiles emissions differed between the adaxial and abaxial leaf epidermes and identified compounds emitted particularly in response to a multiple infestation (cyclohexadecane, dodecane, aromadendrene, and β-elemene). Finally, the carotenoid concentrations in leaves and stems were more affected by multiple than single infestations. Our study highlights and discusses the interplay of biotic stressors within the terpenoid metabolism.

Nano-materials: Science of bottom-up and top-down

Abstract The most frequently used high tech words in the scientific world now are Computer, gene and nanometer. On 29 December 1959, Richard P Feynman [1] gave a talk at the annual meeting of the American Physical society that hasbecome one of the twentieth century’s classic science lectures titled “There is Plenty of Room at the Bottom”. He presented a technological vision of the miniaturization of materials, manipulating and controlling things on asmall scale called “Nanotechnology”. Feynman visualized a technology using a toolbox of nature to build nano-object by atom by atom or molecule by molecule. Taking into account of the future potential of nanoscience, National Science and Technology Council (NSTC) of the White House created the interagency working group on Nanoscience,Engineering and Technology (IWGN) in 1998. A grant of

Ecotype Variability in Growth and Secondary Metabolite Profile in Moringa oleifera: Impact of Sulfur and Water Availability

497 million was granted to National Nanotechnology Institute (NNI) in the year 2001 and made it a top science and technology priority. Scientists are already developing nano-applications that will be bringing revolution in a host of products and services like battery storage capacity, computer chip minimization, drug delivery, facial creams, food processing, agricultural insect control, solar energy management and water purification. The United States have decided to spend US