Katharina Schneider

Molecular cloning of abscisic acid-modulated genes which are induced during desiccation of the resurrection plant Craterostigma plantagineum.

Leaves of the resurrection plant Craterostigma plantagineum Hochst, can be desiccated up to 1% relative water content and are still viable after rehydration. To clone genes related to this extreme desiccation tolerance, an in-vitro system was first developed which allows the induction of the same resurrection response in callus tissue upon treatment with abscisic acid (ABA). Several proteins and in-vitro-synthesized polypeptides were then identified which can be induced both in desiccation-tolerant, naturally dried leaves and in ABA-treated calli surviving after rehydration. Complementary-DNA clones corresponding to mRNAs expressed only in desiccation-tolerant tissues were obtained and classified into several gene families. In hybrid-selected translation experiments, representative cDNA clones were associated with water stress and ABA-inducible polypeptides abundantly expressed in dried leaves and ABA-treated calli. The expression pattern of several of these abundant transcripts was analyzed in RNA-hybridization experiments. Upon stress or ABA treatment the transcription levels increased rapidly, but they declined after relief from the stress state. This, together with data on genomic copy numbers indicated that a set of abundantly expressed genes are involved in the desiccation process of resurrection plants. Data on endogenous ABA contents before and after stress applications and on the physiological effects of exogenous ABA treatments indicate that in Craterostigma plantagineum the induction of an extreme desiccation tolerance is mediated by this plant hormone.

Desiccation leads to the rapid accumulation of both cytosolic and chloroplastic proteins in the resurrection plant Craterostigma plantagineum Hochst

A number of desiccation-related and abscisic-acid (ABA)-inducible transcripts have been isolated from the resurrection plant Craterostigma plantagineum (Scrophulariaceae). They have been analysed at the transcriptional level (D. Bartels et al., 1990, Planta 181, 27–34) and their nucleotide sequences determined (D. Piatkowski et al., 1990, Plant Physiol. 94, 1682–1688). Three such genes encoded polypeptides with substantial homologies to proteins abundantly expressed during late embryogenesis in many higher plants; two other genes encoded novel transcripts. The temporal expression patterns of these gene products and their distribution in different organs of the plant and in callus tissues have now been analysed immunologically. For this, in-situ RNA hybridizations and immunocytochemical studies using tissue sections were carried out at both the light and electron microscope level. All of the products were found to be present in leaf tissue, and some were also found in roots and in seeds. Three desiccation-related proteins were localized in the cytosol, while two others, one associated with the thylakoid membranes, the other soluble in the stroma, were detected in the chloroplast. In C. plantagineum the severe ultrastructural changes observed during the desiccation-rehydration process indicate the need for protectants: the gene products characterized in this publication may be good candidates for this role.

Expression of desiccation-related proteins from the resurrection plant Craterostigma plantagineum in transgenic tobacco

Three cDNAs encoding desiccation-induced proteins from the resurrection plant Craterostigma plantagineum were each ligated to a triplicated CaMV 35S promoter and a nopaline synthase 3′-flanking region in an Agrobacterium vector and introduced into tobacco. Transgenic plants expressed the encoded Craterostigma proteins at high levels. This did not lead to changes in the phenotype, in the growth habit or in basic photosynthetic parameters. In tobacco, one protein was targeted to the chloroplast stroma which is its normal location in Craterostigma. These desiccation-related proteins are not sufficient per se to increase drought tolerance as measured by ion-leakage tests.

Single-Photon Transistor Using a Förster Resonance

An all-optical transistor is a device in which a gate light pulse switches the transmission of a target light pulse with a gain above unity. The gain quantifies the change of the transmitted target photon number per incoming gate photon. We study the quantum limit of one incoming gate photon and observe a gain of 20. The gate pulse is stored as a Rydberg excitation in an ultracold gas. The transmission of the subsequent target pulse is suppressed by Rydberg blockade, which is enhanced by a Förster resonance. The detected target photons reveal in a single shot with a fidelity above 0.86 whether a Rydberg excitation was created during the gate pulse. The gain offers the possibility to distribute the transistor output to the inputs of many transistors, thus making complex computational tasks possible.

PCR-based cloning and segregation analysis of functional gene homologues in Beta vulgaris

Abstract To analyse genetic factors that potentially affect sugar quality and yield in Beta vulgaris, we designed primers based on 18 homologous ESTs and conserved regions of 32 heterologous ESTs encoding gene products that act in the Calvin cycle, the oxidative pentose phosphate cycle, photorespiration, synthesis, transport and degradation of sucrose, glycolysis, the citric acid cycle, nitrogen metabolism and osmoprotection. Data on the amplification of 54 gene homologues from B. vulgaris are presented. Among these are 35 homologues for which DNA sequence information from B. vulgaris is now available for the first time. For genetic mapping a PCR-based strategy using CAPS (cleaved amplified polymorphic sequence), DFLP (DNA fragment length polymorphism), SSCP (single-strand conformation polymorphism) and HD (heteroduplex) analysis was adopted. RFLP analysis was also used in some cases. The different techniques used for the detection of polymorphisms are evaluated with respect to their sensitivity and versatility. In all, 42 functional genes have been assigned to the nine linkage groups of sugar beet.

The most abundant soluble basic protein of the stylar transmitting tract in potato (Solanum tuberosum L.) is an endochitinase

An abundant, pistil-specific basic protein has been purified and characterized from potato (Solanum tuberosum L.). A polymerase chain reaction (PCR) probe was generated for the corresponding gene using oligonucleotides based on internal peptide sequences of the protein, and the PCR probe was further employed to isolate cDNA and genomic clones. The sequence of the gene exhibits up to 70% similarity to previously described endochitinase class 1a protein sequences, and the purified protein possesses chitinase {poly[1, 4-(N-acetyl-β-D-glucosaminide)] glucanohydrolase, EC 3.2.1.14} activity. The protein, termed SK2, has been located by immunocytochemistry to the intercellular matrix of the stylar transmitting tract. Immunoblot analysis has shown SK2 to be distinct from the wound-induced chitinases of potato. The SK2-class of chitinase is restricted in its distribution within the Solanaceae to the sub-family Solanoidae, which includes cultivated tomato and potato species. It was absent from the Cestroidae species tested (Petunia hybrida, Nicotiana tabacum). A role for SK2 endochitinase in protecting the ovary against pollen-tubemediated pathogen ingress is proposed.

Multiplexed, linkage group-specific SNP marker sets for rapid genetic mapping and fingerprinting of sugar beet (Beta vulgaris L.)

A set of single nucleotide polymorphism (SNP) markers has been developed for each of the nine linkage groups of sugar beet. Each set can monitor the polymorphic state at five to six linked marker loci. In each set, the loci selected for marker development are first amplified in a multiplexed reaction. These amplification products are the basis for sequence-specific elongation of primers adjacent to SNP positions. The extension step revealing SNP loci is based on fluorescently labelled nucleotides. In each set, primers developed to reveal SNP alleles differ in length to allow clear peak resolution in capillary electrophoresis. The nine linkage group (LG) - specific sets provide information on the polymorphism at a total of 52 SNP marker loci. Using the SNP-based tool, groups of concerned loci have been anchored to three different linkage maps of sugar beet. In a second experiment, sugar beet breeding lines have been fingerprinted. The use of the nine sets of LG-specific markers in sugar beet genetics and breeding is discussed. The information necessary to specify the 52 marker loci, as well as their map location, and all details concerning SNP assays, including allele type and nature of mutation, are reported.

Initial-state selective study of ionization dynamics in ion-Li collisions

Kinematically complete experiments were performed on the ionization of a laser-cooled lithium target from different initial states, Li(2s), Li(2p) and Li(1s), by 6 MeV H+ and 1.5?MeV?amu?1 O8 + impact. In the measured doubly differential cross sections as a function of electron energy and transverse momentum transfer, a significant initial state dependence is found. Furthermore, comparison to quantum mechanical theory shows surprising discrepancies for Li(2s) and Li(1s) while there is good agreement for the Li(2p) initial state.

Kinematically Complete studies on Mutual Projectile and Target Ionization

Mutual projectile and target ionizations (MPTI) of 1MeV/amu N4+ and N5+ +He collisions have been studied in kinematically complete experiments, the data is presented in four-particle (4-D) Dalitz plots. comparison to eikonal approximation (EA) calculation results shows qualitatively good agreement.

Systematic Analysis of Four-Particle Dalitz Plots for Double Ionization

Using a split-mirror setup attached to a Reaction Microscope at the Free electron LASer in Hamburg (FLASH) we traced as function of time the migration of a hydrogen atom in C2H4+ from one end of the molecule to the other by coincident CH+ + CH3+ fragment detection. In addition, the observed H3++C2H+ channel provides for the first time evidence for an isomerization-induced formation mechanism of H3+ molecules.