Are penetrometer measurements useful in predicting emergence of sugar beet (Beta vulgaris L.) seedlings through a crust?

Soil crusting strongly affects seedling emergence. Laboratory experiments were carried out to analyse the emergence of sugar beet (Beta vulgarisL.) seedlings from beneath a crust, and to determine whether mechanical models using penetrometer measurements could predict the final emergence rates. Wet and dry crusts were created under a rainfall simulator. An ascending micropenetrometer was used to measure the crust strength in conditions as close as possible to those encountered by seedlings. The mode of the emergence was observed for both micropenetrometer probe and seedlings. While 94% of the emerged seedlings penetrated the wet crusts, only 6% broke it. The probe penetrated the wet crust in only 46% of cases, and broke it in the other 54%. In contrast, 39% of the seedlings emerged directly through a crack in the dry crust and 55% emerged by breaking (5% lifted a detached fragment and 1% penetrated the crust). In the same conditions, the probe emerged directly through a crack in only 4% of cases; 67% by breaking and 29% by lifting a crust fragment. The force recorded by the penetrometer was 0.05 – 0.80 N, and it varied with the mode of emergence. The seedling growth force distribution was 0 – 0.30 N (mean = 0.09 N). Mechanical models comparing the force exerted by the micropenetrometer probe to the seedling force distribution according to the mode of the emergence were used to predict final emergence rates. Penetrometer measurements appeared to overestimate the mechanical resistance encountered by the seedlings, leading to an underestimation of emergence rates under all emergence conditions. This overestimation of crust strength was attributed to the rigidity of the probe as opposed to the flexibility of hypocotyls.     

Spatial analysis of nuclear and cytoplasmic DNA diversity in wild sea beet (Beta vulgaris ssp. maritima) populations: do marine currents shape the genetic structure?

Patterns of seed dispersal in the wild sea beet (Beta vulgaris ssp. maritima) are predicted to be influenced by marine currents because populations are widely distributed along the European Atlantic coast. We investigated the potential influence of marine currents on the pattern of spatial genetic structuring in natural populations of sea beet. Populations were located along the French coasts of the Anglo-Norman gulf that features peculiar marine currents in the Channel. Thirty-three populations were sampled, among which 23 were continental and 10 were insular populations located in Jersey, Guernsey and Chausey, for a total of 1224 plants genotyped. To validate the coastal topography influence and the possibility of marine current orientated gene flow on the genetic features of sea beet populations, we assessed patterns of genetic structuring of cytoplasmic and nuclear diversity by: (i) searching for an isolation-by-distance (IBD) pattern using spatial autocorrelation tools; (ii) using the Monmonier algorithm to identify genetic boundaries in the area studied; and (iii) performing assignment tests that are based on multilocus genotype information to ascertain population membership of individuals. Our results showed a highly contrasted cytoplasmic and nuclear genetic differentiation and highlighted the peculiar situation of island populations. Beyond a classical isolation-by-distance due to short-range dispersal, genetic barriers fitting the orientation of marine currents were clearly identified. This suggests the occurrence of long-distance seed dispersal events and an asymmetrical gene flow separating the eastern and western part of the Anglo-Norman gulf.     

Development of real-time PCR method for the detection and the quantification of a new endogenous reference gene in sugar beet “Beta vulgaris L.”: GMO application

Key message

Here, we describe a new developed quantitative real-time PCR method for the detection and quantification of a new specific endogenous reference gene used in GMO analysis.

Abstract

The key requirement of this study was the identification of a new reference gene used for the differentiation of the four genomic sections of the sugar beet (Beta vulgaris L.) (Beta, Corrollinae, Nanae and Procumbentes) suitable for quantification of genetically modified sugar beet. A specific qualitative polymerase chain reaction (PCR) assay was designed to detect the sugar beet amplifying a region of the adenylate transporter (ant) gene only from the species of the genomic section I of the genus Beta (cultivated and wild relatives) and showing negative PCR results for 7 species of the 3 other sections, 8 related species and 20 non-sugar beet plants. The sensitivity of the assay was 15 haploid genome copies (HGC). A quantitative real-time polymerase chain reaction (QRT-PCR) assay was also performed, having high linearity (R ² > 0.994) over sugar beet standard concentrations ranging from 20,000 to 10 HGC of the sugar beet DNA per PCR. The QRT-PCR assay described in this study was specific and more sensitive for sugar beet quantification compared to the validated test previously reported in the European Reference Laboratory. This assay is suitable for GMO quantification in routine analysis from a wide variety of matrices.     

Uridine 5′-diphospho-D-glucose-dependent vectorial sucrose synthesis in tonoplast vesicles of the storage hypocotyl of red beet (Beta vulgaris L. ssp. conditiva)

Tonoplast vesicles were prepared from red-beet (Beta vulgaris L. ssp. conditiva) hypocotyl tubers (beetroot) known to store sucrose. Uptake experiments, employing uridine 5-diphospho-[¹⁴C]glucose (UDP-[¹⁴C]glucose) showed the operation of an UDP-glucose-dependent group translocator for vectorial synthesis and accumulation of sucrose, recently described for sugarcane and red-beet vacuoles and for tonoplast vesicles prepared from sugarcane suspension cells. Characterization of the kinetic properties yielded the following results. Uptake of UDP-glucose was linear for 15 min. The apparent K _m was 0.75 mM for UDP-glucose (at pH 7.2, 1 mM Mg²⁺), V _max was 32 nmol·(mg protein)^-1·min^-1. The incorporation of UDP-glucose exhibited a sigmoidal substrate-saturation curve in the absence of Mg²⁺, the Hill coefficient (n _H) was 1.33; Michaelis-Menten kinetics were obtained, however, in the presence of 1 mM MgCl₂. For the reaction sequence under the control of the group translocator a dual pH optimum was found at pH 7.2 and 7.9, respectively. All reaction intermediates and the end product sucrose could be identified by two-dimensional high-performance thin-layer chromatography and autoradiography. The distribution pattern of radioactivity showed almost uniformly high labeling of all intermediates and sucrose. The physiological relevance of the results is discussed in the light of the fact that the tonoplast of red-beet storage cells accommodates two mechanisms of sucrose uptake (i) vectorial sucrose synthesis and (ii) direct ATP-dependent sucrose assimilation.Abbreviations HPTLC High-performance thin-layer chromatography - UDP uridine 5-diphosphate - SDS sodium dodecyl sulfate     

Resistance to metamitron in Chenopodium album from sugar beet. a tale of the (un)expected?

Metamitron is a key herbicide in modern low rate weed control programs in sugar beet. Fat hen (Chenopodium album, CHEAL) is a common, highly competitive, weed in sugar beet and one of the targets of metamitron. Recently, unsatisfactory control of fat hen has been reported in several sugar beet fields situated in various regions in Belgium. Weather conditions as well as the mere fact of using low rate systems have been blamed for these poor performances. To address the question "Is the recently recorded poor control of C. album due to decreased sensitivity to metamitron", greenhouse bioassays were carried out. A first experiment was conducted applying metamitron (0, 350, 700 and 1,400 g ai/ha) postemergence to three "suspected" C. album populations originating from sugar beet fields with unsatisfactory control by standard metamitron based treatment schemes ('Ligne', 'Outgaarden' and 'Boutersem I' respectively) and to one sensitive population originating from an untreated garden site ('Gent'). In a second experiment seven population, five "suspected" fat hen populations from sugar beet fields ('Boutersem I', 'Boutersem II', 'Postel', 'Vissenaken' and 'Kortessem' respectively), one sensitive reference population 'Herbiseed' and one atrazine-resistant reference population 'ME.85.01', were submitted to metamitron (0, 1, 2 and 4 mg ai/kg air-dry soil) and atrazine (1.5 mg ai/kg air-dry soil) preplant incorporated. All "suspected" C. album populations displayed a significantly lower sensitivity to metamitron compared to the sensitive populations ('Gent' and 'Herbiseed') that never had been exposed to this herbicide. As target site cross-resistance of atrazine-resistant C. album, selected by atrazine in maize, to metamitron has been known for a long time, cross-resistance of C. album populations in sugar beet grown on fields with "maize - atrazine" containing rotations might be expected to appear. The outcome of the experiment with atrazine preplant incorporated was the confirmation of resistance in all "suspected" populations ('Boutersem I', 'Boutersem II', 'Postel', 'Vissenaken' and 'Kortessem'). However, some "suspected" populations came from fields with no background of cropping with maize and use of atrazine. So, the question remains whether these triazine-resistant C. album had been imported, e.g. with slurry, or the rather unexpected possibility that metamitron itself did select for metamitron-resistant biotypes bearing cross-resistance to atrazine, had become reality.     

Paternity determination in the adder (Vipera berus)—DNA fingerprinting or random amplified polymorphic DNA?

We performed breeding experiments with adders (Vipera berus) to determine whether multiple matings may result in multiple paternity. DNA fingerprinting of mothers, their offspring, and possible fathers using a polydinucleotide probe [(TG) _n ] gave a low overall similarity between unrelated individuals (0.18±0.07; SD) and an average of 17 bands that were male-specific. In no cases were there fewer than seven paternal-specific bands present in the fingerprint of an offspring, enabling us unambiguously to identify the biological father among five males. Multiple paternity was detected in the investigated broods with offspring sired exclusively by the captive males. PCR amplification of random amplified polymorphic DNA (RAPD) using 16 decamer primers gave 76 bands and an average similarity of 0.95 (±0.01) between the males, which were collected at different, geographically well-separated localities. Although there were on average 8.3 (±1.9) bands that differ between males in pairwise comparisons, there were only 1.9 (±1.1) bands per male that are specific for a particular individual. Thus, RAPDs are adequate for paternity determination only in experiments with a low number of males, whereas DNA fingerprinting offers sufficient information to discriminate between large numbers of putative fathers.The Swedish Natural Science Research Council, the Nilsson-Ehle Foundation, and the Erik Philip-Sörensen Foundation supported our research.     

DNA fingerprinting—A useful tool in the taxonomy of apomictic plant groups

DNA fingerprinting has proved useful for the analysis of genotypic distribution and estimation of genetic relatedness in apomictic plant groups likeRubus, Amelanchier, Hieracium andTaraxacum. Speciation through interspectific hybridization has been demonstrated in one case involving apomicticRubus species. The application of molecular markers to progeny derived from experimental cross-pollinations has yielded information on levels of apomixis as well as on its inheritance and regulation in e.g.Rubus, Poa, Pennisetum andTripsacum.     

Cell-wall antigens in mesophyll cells and mesophyll-derived protoplasts of sugar beet: possible implication in protoplast recalcitrance?

We have investigated the possible relation between plant cell-wall constituents and the recalcitrance of the cell to regenerate organs and whole plants in vitro. A temporal and spatial expression of several carbohydrate epitopes was observed both within leaf tissue used for protoplast isolation and within new walls reformed by recalcitrant mesophyll protoplasts of sugar beet ( Beta vulgaris L.); these include four pectic epitopes, one xyloglucan (rhamnogalacturonan I) epitope, two carbohydrate motifs of arabinogalactan proteins (AGPs) and callose. The walls of mesophyll cells and newly formed walls of protoplasts were similar with respect to the presence of large amounts of pectins recognized by JIM7 antibodies, the scarcity of JIM5-pectins and the complete absence of LM5-responding pectin molecules. Their main differences were the significantly higher accumulation of LM6-recognizing pectins and the very conspicuous greater accumulation of AGPs and callose in walls deposited by protoplasts than in those synthesized by donor cells.     

Rainfall preceding egg-laying — a factor of breeding success in Common Terns (Sterna hirundo)

Summary The temporary reduction of clutch size, egg size and breeding success of the Common Tern during the breeding period of 1983 at the Lower Saxonian Wadden Sea (West Germany) was correlated with heavy rainfalls on the days preceding egg-laying (Figs. 2–4). Possible effective mechanisms and the result that the reduction of clutch size was not observed for colonies at the mainland coast are being discussed (Fig. 4).Supported by the Deutsche Forschungsgemeinschaft     

MALDI-TOF MS in microbiological diagnostics—identification of microorganisms and beyond (mini review)

Few developments in microbiological diagnostics have had such a rapid impact on species level identification of microorganisms as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Conventional differentiation methods rely on biochemical criteria and require additional pre-testing and lengthy incubation procedures. In comparison, MALDI-TOF MS can identify bacteria and yeast within minutes directly from colonies grown on culture plates. This radically new, methodically simple approach profoundly reduces the cost of consumables and time spent on diagnostics. The reliability and accuracy of the method have been demonstrated in numerous studies and different systems are already commercially available. Novel applications of the system besides microbial species level identification are also being explored. This includes identification of pathogens from positive blood cultures or directly from patient samples, such as urine. Currently, intriguing MALDI-TOF MS developments are being made regarding the phenotypic detection of certain antibiotic resistance mechanisms, e.g., β-lactamases and carbapenemases. This mini review provides an overview of the literature in the field and also includes our own data and experiences gathered from over 4 years of routine MALDI-TOF MS use in a university hospital’s microbiological diagnostics facility.     

Landscape of π–π and sugar–π contacts in DNA–protein interactions

There were 1765 contacts identified between DNA nucleobases or deoxyribose and cyclic (W, H, F, Y) or acyclic (R, E, D) amino acids in 672 X-ray structures of DNA–protein complexes. In this first study to compare π-interactions between the cyclic and acyclic amino acids, visual inspection was used to categorize amino acid interactions as nucleobase π–π (according to biological edge) or deoxyribose sugar–π (according to sugar edge). Overall, 54% of contacts are nucleobase π–π interactions, which involve all amino acids, but are more common for Y, F, and R, and involve all DNA nucleobases with similar frequencies. Among binding arrangements, cyclic amino acids prefer more planar (stacked) π-systems than the acyclic counterparts. Although sugar–π interactions were only previously identified with the cyclic amino acids and were found to be less common (38%) than nucleobase–cyclic amino acid contacts, sugar–π interactions are more common than nucleobase π–π contacts for the acyclic series (61% of contacts). Similar to DNA–protein π–π interactions, sugar–π contacts most frequently involve Y and R, although all amino acids adopt many binding orientations relative to deoxyribose. These DNA–protein π-interactions stabilize biological systems, by up to approximately ?40 kJ mol^?1 for neutral nucleobase or sugar–amino acid interactions, but up to approximately ?95 kJ mol^?1 for positively or negatively charged contacts. The high frequency and strength, despite variation in structure and composition, of these π-interactions point to an important function in biological systems.     

Construction of a YAC library from a Beta vulgaris fragment addition and isolation of a major satellite DNA cluster linked to the beet cyst nematode resistance locus Hs1 pat−1

A YAC library was constructed from the Beta vulgaris fragment addition AN5-203b. This monosomic fragment addition harbors an approximate 12-Mbp fragment of B.patellaris chromosome 1 accomodating the Hs1 ^pat-1 conferring resistance to the beet cyst nematode (Heterodera schachtii). The YAC library consists of 20,000 YAC clones having an average size of 140 kb. Screening with organelle-specific probes showed that 12% of the clones contain chloroplast DNA while only 0.2% of the clones hybridizes with a mitochondrial specific probe. On the basis of a sugar beet haploid genome size of 750 Mbp this library represents 3.3 haploid genome equivalents. The addition fragment present in AN5-203b harbors a major satellite DNA cluster that is tightly linked to the Hs1 ^pat-1 locus. The cluster is located on a single 250-kb EcoRI restriction fragment and consists of an estimated 700–800 copies of a 159-bp core sequence, most of which are arranged in tandem. Using this core sequence as a probe, we were able to isolate 1 YAC clone from the library that contains the entire 250-kb satellite DNA cluster.Abbreviations YAC Yeast artificial chromosome - BCN beet cyst nematode - RAPD random amplified polymorphic DNA - RFLP restriction fragment length polymorphism     

Study of artemisinin and sugar accumulation in Artemisia vulgaris and Artemisia dracunculus “hairy” root cultures

We studied the effect of genetic transformation on biologically active compound (artemisinin and its co-products (ART) as well as sugars) accumulation in Artemisia vulgaris and Artemisia dracunculus “hairy” root cultures. Glucose, fructose, sucrose, and mannitol were accumulated in A. vulgaris and A. dracunculus “hairy” root lines. Genetic transformation has led in some cases to the sugar content increasing or appearing of nonrelevant for the control plant carbohydrates. Sucrose content was 1.6 times higher in A. vulgaris “hairy” root lines. Fructose content was found to be 3.4 times higher in A. dracunculus “hairy” root cultures than in the control roots. The accumulation of mannitol was a special feature of the leaves of A. vulgaris and A. dracunculus control roots. A. vulgaris “hairy” root lines differed also in ART accumulation level. The increase of ART content up to 1.02?mg/g DW in comparison with the nontransformed roots (up to 0.687?mg/g DW) was observed. Thus, Agrobacterium rhizogenes-mediated genetic transformation can be used for obtaining of A. vulgaris and A. dracunculus “hairy” root culture produced ART and sugars in a higher amount than mother plants.