A Fiberless Seed Mutation in Cotton Is Associated with Lack of Fiber Cell Initiation in Ovule Epidermis and Alterations in Sucrose Synthase Expression and Carbon Partitioning in Developing Seeds1

Fiber cell initiation in the epidermal cells of cotton (Gossypium hirsutum L.) ovules represents a unique example of trichome development in higher plants. Little is known about the molecular and metabolic mechanisms controlling this process. Here we report a comparative analysis of a fiberless seed (fls) mutant (lacking fibers) and a normal (FLS) mutant to better understand the initial cytological events in fiber development and to analyze the metabolic changes that are associated with the loss of a major sink for sucrose during cellulose biosynthesis in the mutant seeds. On the day of anthesis (0 DAA), the mutant ovular epidermal cells lacked the typical bud-like projections that are seen in FLS ovules and are required for commitment to the fiber development pathway. Cell-specific gene expression analyses at 0 DAA showed that sucrose synthase (SuSy) RNA and protein were undetectable in fls ovules but were in abundant, steady-state levels in initiating fiber cells of the FLS ovules. Tissue-level analyses of developing seeds 15 to 35 DAA revealed an altered temporal pattern of SuSy expression in the mutant relative to the normal genotype. Whether the altered programming of SuSy expression is the cause or the result of the mutation is unknown. The developing seeds of the fls mutant have also shown several correlated changes that represent altered carbon partitioning in seed coats and cotyledons as compared with the FLS genotype.

Expression of a delta 9 14:0-acyl carrier protein fatty acid desaturase gene is necessary for the production of omega 5 anacardic acids found in pest-resistant geranium (Pelargonium xhortorum).

Anacardic acids, a class of secondary compounds derived from fatty acids, are found in a variety of dicotyledonous families. Pest resistance (e.g., spider mites and aphids) in Pelargonium xhortorum (geranium) is associated with high levels (approximately 81%) of unsaturated 22:1 omega 5 and 24:1 omega 5 anacardic acids in the glandular trichome exudate. A single dominant locus controls the production of these omega 5 anacardic acids, which arise from novel 16:1 delta 11 and 18:1 delta 13 fatty acids. We describe the isolation and characterization of a cDNA encoding a unique delta 9 14:0-acyl carrier protein fatty acid desaturase. Several lines of evidence indicated that expression of this desaturase leads to the production of the omega 5 anacardic acids involved in pest resistance. First, its expression was found in pest-resistant, but not suspectible, plants and its expression followed the production of the omega 5 anacardic acids in segregating populations. Second, its expression and the occurrence of the novel 16:1 delta 11 and 18:1 delta 13 fatty acids and the omega 5 anacardic acids were specific to tall glandular trichomes. Third, assays of the recombinant protein demonstrated that this desaturase produced the 14:1 delta 9 fatty acid precursor to the novel 16:1 delta 11 and 18:1 delta 13 fatty acids. Based on our genetic and biochemical studies, we conclude that expression of this delta 9 14:0-ACP desaturase gene is required for the production of omega 5 anacardic acids that have been shown to be necessary for pest resistance in geranium.

Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae): adequação de uma dieta artificial e avaliação do seu controle biológico com Trichogramma pretiosum Riley em tomateiro

Tuta absoluta (Meyrick, 1917) é uma das pragas-chave da cultura do tomate e outras solanáceas na América do Sul e atualmente também na Eurásia e África. Devido aos grandes prejuízos que causa à cultura, são principalmente usados inseticidas para o seu controle. Entretanto, na busca de estratégias mais sustentáveis, cada dia adquire maior importância o uso do controle biológico, como uma das estratégias do manejo integrado de pragas. Para o desenvolvimento destas estratégias é fundamental desenvolver um método de criação de T. absoluta em laboratório, em dieta artificial, sem necessitar do hospedeiro natural, muitas vezes difícil de ser obtido e mantido em laboratório, e, de grande importância para produzir parasitoides específicos para esta praga. Dentre os parasitoides mais usados para ovos de lepidópteros está Trichogramma pretiosum Riley 1879 que é usado no controle biológico aplicado desta praga. Tendo como foco principal T. absoluta, neste trabalho foram pesquisados 1) a seleção de uma dieta artificial para este lepidóptero baseando-se em características físicas e químicas, avaliando o seu desempenho por várias gerações em laboratório, e 2) avaliação de aspectos biológicos e reprodutivos de T. pretiosum parasitando ovos de T. absoluta e aspectos físicos da planta (tricomas) para compreender o controle biológico desta praga no tomateiro. Foi encontrado que uma dieta à base de germe-de-trigo, caseína e celulose é apropriada para a criação deste lepidóptero, já que o inseto mostrou adaptação à mesma no transcorrer das gerações com base em características biológicas e de tabela de vida; adicionalmente, os ovos provenientes de T. absoluta alimentada com dieta artificial são comparáveis aos da dieta natural, no parasitismo de T. pretiosum. Com relação ao controle biológico foi demonstrado que este parasitoide desenvolvido em ovos de T. absoluta, diminui seu tamanho e desempenho com o transcorrer das gerações, apresentando menor capacidade de voo do que os insetos produzidos em A. kuenhiella, sendo necessária a liberação de altas densidades de parasitoides por ovo da praga. Foi observado que, embora o parasitismo de T. pretiosum de ovos de T. absoluta seja melhor em variedades com poucos tricomas, uma alta densidade destas estruturas não impede o controle da praga alvo dependendo da disposição destas estruturas. O controle biológico de T. absoluta com T. pretiosum tem uma ação momentânea, sendo necessárias liberações frequentes devido ao fato de os parasitoides desenvolvidos na praga serem menos competitivos com aqueles provenientes do hospedeiro alternativo que apresenta ovos maiores do que T. absoluta.

Etablierung des VIGS-Systems zur Untersuchung trichom-spezifischer Gene in Tomate

Bei der Abwehr von Pflanzen gegen biotische und abiotische Stressfaktoren spielt die Oberfläche der Pflanzen eine große Rolle. Die äußere Epidermisschicht grenzt das Pflanzeninnere von der Umgebung ab und schützt dieses. Die Epidermis der meisten Pflanzen bildet haarartige Ausstülpungen aus. Diese werden als Trichome bezeichnet. Sie sind in einer Vielfalt von Formen, Größen und Strukturen vorzufinden und weisen unterschiedliche Stoffwechselaktivitäten auf. Auf Grund ihrer Lage haben sie einen Einfluss auf eine Vielzahl von Wechselwirkungen mit der Umgebung der Pflanze. Man unterscheidet Trichome in nicht-glanduläre und glanduläre Trichome. In den sekretorischen Kopfzellen der glandulären Trichome werden unterschiedliche Sekundärmetaboliten gebildet und gespeichert. Durch Berührung lösen sich die Kopfzellen der glandulären Trichome von der Pflanze und geben diese Metaboliten an die Umwelt ab. Diese Stoffe haben einen großen Einfluss bei der Abwehr der Pflanze gegen Pflanzenfresser und Schädlinge. So werden klebrige Harze als Insektenfallen gebildet oder mittels spezieller Duftstoffe die Feinde der Schädlinge angelockt. Viele dieser Verbindungen sind daher für die Wirtschaft von Interesse, als Duftstoffe oder aufgrund ihrer weiteren Eigenschaften als Wirkstoffe für die Medizin. Eine Möglichkeit liegt in der Produktion neuer Verbindungen in großem Maßstab in den Trichomen.(...)

Global distributions of diazotrophs abundance, biomass and nitrogen fixation rates - Collection of source datasets - Contribution to the MAREDAT World Ocean Atlas of Plankton Functional Types

The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedented global data set for ecological and biochemical analysis and modeling as well as a clear mandate for compiling additional existing data and for focusing future data gathering efforts on key groups in key areas of the ocean. The present collection presents the original data sets used to compile Global distributions of diazotrophs abundance, biomass and nitrogen fixation rates

Global distributions of diazotrophs abundance and biomass - Depth integrated values computed from a collection of source datasets - Contribution to the MAREDAT World Ocean Atlas of Plankton Functional Types

The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedented global data set for ecological and biochemical analysis and modeling as well as a clear mandate for compiling additional existing data and for focusing future data gathering efforts on key groups in key areas of the ocean. The present data set presents depth integrated values of diazotrophs abundance and biomass, computed from a collection of source data sets.

Pollen analysis of sediment profile WO1 from Wollingster See

A palynological study of a 15 m sediment core from the centre of Lake Wollingst (water depth 14,5 m) is presented. The pollen record shows 3 lateglacial thermomers, called Meiendorf, Bölling, Alleröd and the early holocene Friesland-Thermomer. The succession of forest vegetation taking place on the lake surroundings during the Holocene was typical for older moraine soils which are poor in nutrients: forest vegetation started with birch and pine, followed by hazel, oak and elm in the Boreal and by alder, lime and ash-tree in the Atlantic. Beech and hornbeam reached the area during Subboreal. However, due to the poor soils they spread out only after the Iron Age. With the deforestation during the medieval time the lake lost its character of a primeval forest lake. Lake Wollingst was oligotrophic since its origin at the end of the Pleniglacial. After medieval forest-clearing the lake has changed its quality of water particularly in connection with hemp- and flax-rotting. The modem sediments in this profile are completely disturbed. They contain reworked material, a lot of blue-green algae and remains of Bosmina longirostris indicating eutrophic conditions.