Browsing by Person "Blaich, Rolf"

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Entwicklung innovativer Pflanzenschutzprodukte und -verfahren als umweltfreundliche Alternativen zur Bekämpfung von Mehltaupilzen : Bericht im Rahmen des Forschungsprojektes: „Silizium als Aktivator bei Kulturpflanzen“
(2019) Raupp, Manfred G.; Weinmann, Markus; Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ e. V. (AiF) Projekt GmbH, Berlin; Madora GmbH, Lörrach; Römheld, Volker; Neumann, Günter; Blaich, Rolf; Merkt, Nikolaus
Powdery mildews are among the most important diseases in many crop plants. In all sectors of crop production (agriculture, viticulture, horticulture and orchards) powdery mildew fungi can cause severe damage under field as well as greenhouse conditions. Although organic synthetic fungicides have been used to combat powdery mildews in conventional and integrated agriculture for decades, organic farming lacks effective alternatives to the ecologically questionable sulfur fungicides. Yet, also for integrated or conventional crop production, alternatives or supplements for a reduction and more effective use of synthetic fungicides would be desirable to optimize the production of high quality food with the help of environmentally friendly means. Objective of the present work was the development of innovative crop protection products and application strategies to combat powdery mildew fungi with respect to the knowledge on resistance-enhancing effects of an improved silicon (Si), manganese (Mn) and zinc (Zn) supply to the plants. Furthermore, various plant extracts have recently received renewed attention. Among other active natural agents, garlic (Allium sativum L.) is known for its fungitoxic effect and at the same time high Mn and Zn contents. With the present work, an overview of possible approaches to control powdery mildew in grapevine by use of Si, Mn, Zn and plant extracts from garlic has been elaborated in greenhouse experiments. In this regard, the physiological significance of Si, Mn and Zn for the expression and strengthening of plant own resistance mechanisms was distinguished from the effectiveness of spray applications for forming passive silicate crusts as mechanical infection barriers. The physiological Si status of the plants could be clearly improved only by soil rather than foliar application of silicates. Regarding the soil application of silicates, however, no practical applications are known, how silicon fertilizers can be distributed under field conditions in the soil and brought into the rhizosphere to continuously ensure high rates of Si uptake. There is also still considerable uncertainty whether the soil application of silicates in non-Si accumulators, such as grapevines, can result in sufficient Si uptake for an effective expression of resistance mechanisms. The most impressive effects in the control of powdery mildew were achieved with the spray application of potassium silicate in combination with wetting agents to form silicate crusts on the leaf surface. The positive influence of Mn and Zn on the effectiveness of spray applications of potassium silicate and the adequate compatibility of Mn and Zn chelates with potassium silicate suggest that the interactions between Si, Mn and Zn should be considered for further product development. The application of garlic extract did not result in sufficient efficiency, although protective and curative properties could be observed. Allicin, supposed to be the active ingredient of garlic extract, has a broad spectrum of antimicrobial activity and is one of the few agents for which no development of resistance has been found in microorganisms so far. Therefore, the interest in this agent for the development of biological plant protection products is expected to increase.
Lockerbeerigkeit bei Klonen von Spätburgunder (Pinot noir) : Analyse von molekularen Markern und der Einfluss von Gibberellin auf die Traubenmorphologie
(2014) Hoffmann, Petra; Blaich, Rolf
In viticulture, the architecture of the grape cluster affects the quality of the grapes. Compact grape clusters are more prone to B. cinerea infection, which reduces yield (Vail et al. 1998, Vail et al. 1991). Loose clusters have longer pedicel and rachis structures (Alleweldt 1959) and are less susceptible to B. cinerea. For this reason, the cultivation of clones with the loose cluster trait is of great interest. Loose clusters can result from the application of phytohormones, the spacing of the flower clusters, the thinning of fruit, or a reduced pruning. These treatments reduce berry set and promote pedicle elongation when applied to clones with compact clusters (Alleweldt 1959). Genetically based loose clustered grape phenotypes occur among grapevine cultivars. In this study we are able to differentitate between losse and compact clones using the marker FlExp2 on the basis of sequence data. The loose cluster clones show a 4 bp deletion at 219-222 bp and a C/T transition at 231 bp, unlike the compact cluster clones. In all tested Pinot ssp. clones, the sequence correlated to the phenotype. The marker was tested on other varieties such as Riesling, Gewurztraminer, Chardonnay, Chenin blanc, Cardinal and White Chasselas. The phenotypes were again consistent with the sequence. In the case of loose clustered table grapes, a deletion occurs instead of the transition at 231 bp. Additionally, the variety White Gutedel demonst- rated a C/T transition at 217 bp. These results were confirmed by sequencing 30 clo- nes (loose and compact clusters) in two repetitions in both directions. Both markers shwoed two fragments with a four bp difference. The amplification products are a In- del/SNP mutation for loose cluster and a „CTTT“ mutation for copmact cluster grapes.The CAPS and the SCAR marker identified that the trait of bunch architecture is heterozygous. The sequence of the amplification products was distinct for loose and compact cluster types. The SCAR marker shows two amplification products at 162 bp and 166 bp and the CAPS marker at 283 bp and 287 bp. The heterozygosity didn ́t produce a molecular marker for the MAS. In silico, analysis shows that the identified locus is in the Exon in the Vlexp1 gene. This gene is an expansin gene which is responsible for cell elongation (McQueen- Mason 1992). A part of the role which the hormones play in grape Morphology was analyzed in this study. The inflorescences of the genetically loose clustered clone 1-84 Gm did not show increased gibberellin concentration, indicating that gibberellin does not have a influence on the genetic based loose clone (1-84 Gm). However, the auxin concentra- tion in inflorescences of loose cluster clones increases earlier and remains high lon- ger than in those of the compact cluster clone 18 Gm. After a treatment with gib- berellin, the clone 1-84 Gm exhibited increased concentration of both gibberellin and auxin and formed even looser clusters. Similarly, the same treatment applied to the compact clone 18 Gm resulted in looser clusters and increased concentration of gib- berellin and auxin with a higher concentration of auxin for a longer period of time. It remains unclear precisely how the gibberellin treatment induces looser clusters. It may be that there is an interaction between gibberellin and auxin or that the auxin alone causes the cell extension. It remains an open question whether expansin toge- ther with gibberellin or auxin is responsible for the development of loose clusters, or if it is caused by a gibberellin auxin interaction. The growth pattern of the stalks and inflorescences were identified in order to put these results in context with the results of the hormone and genetic analysis. The stalks and inflorescences of the treated and untreated clones were measured weekly before GA3-application and continued four weeks after application. The growth of the flower clusters ended three weeks af- ter anthesis while the stalks grew continuously. In the loose cluster clone 1-84 Gm, the growth of stalks and flower clusters was significantly larger than in the compact cluster clone 18 Gm. The growth behavior of the peclone 18 Gm when treated with gibberellin was identical to the clone 1-84 Gm without gibberellin treatment. Gib- berellin treatment caused a significant increase in the growth of the stalk and flower clusters. The treated loose cluster clones formed the largest stalks while the untrea- ted compact cluster clone 18 Gm the smallest. Such clone growth behavior results in loose cluster architecture.
Mechanisms of frost adaptation and freeze damage in grapevine buds
(2002) Badulescu Valle, Radu Virgil; Blaich, Rolf
Mechanisms of frost hardening in compound (latent) buds of the grapevine cultivar ?Bacchus? were tested with different methods during three winters. The investigated parameters were LTE/HTE (low temperature exotherm/high temperature exotherm), water content, starch, sugar- and anions combination and bud histology. Water content from wood and buds was determined regularly every 2 weeks from March 1998 until Mai 2000. The lowest water content in wood and buds (about 40 %) was found between November and February. In general shoot sections and buds from the apical shoot area contained less water than in the basal area. Sugars and anions were analyzed with HPLC. The highest concentrations of soluble sugars were found in basal buds of the shoot, the lowest concentration in buds of the apical shoot area. Sucrose was the predominant soluble sugar, it was accompanied by glucose, fructose, sucrose, raffinose, and also stacchyose which was hitherto not described for grapevine buds. The concentration of soluble sugars increased during autumn and reached its maximum (around 150 mg/g dry matter) in November/December until the beginning of January then it decreased again to around 30 mg/g at bud burst. The predominant anion was sulphate while chloride could be detected only in traces. The anions reached their maximum at the beginning of January and in mid April. To evaluate the exotherm measuring method, model experiments were carried out with water drops (1µl) on filter paper and with small plant parts (leaf, stems, flower parts). Both the plant parts and the destilled water on the cellulose fiber freeze mainly between ?8 and ?15°C (an influence of the low osmotic value of the plant sap could not be found). After the first freezing the specimen were thawed and freezing repeated. The freezing points of the first and the second freezing cycle were significantly correlated. This shows that freezing does not occur at random, but is determined by ice nucleation sites characteristic for each sample. These sites even survive the physical destruction of the cells by the ice cristals. Further model experiments were carried out to get indications on possible barriers to ice cristal growth in plant tissue. Exotherm analysis was used to determine the freezing point of grapevine buds which is accompanied by a transient temperature rise called exotherm. The grapevine buds show 2 or more exotherms, one or two HTEs (high temperature exotherms) between ? 5 °C and ?10°C and the LTE (low temperature exotherm, sometimes more than one ) between ?10°C and ?25°C depending on the frost adaption of the buds. The HTEs are assumed to indicate the freezing of surface water or apoplastic water in the subtending tissue (bud pad), whereas the LTE (or LTEs) seem to be caused by freezing of the primary (and secondary) buds (shoot primordiy of the compound bud). The temperature minimum of the LTEs (down to ? 25 °C) is reached in January/February and is not influenced by humidity which, however, changes the THE values occuring usually around ? 10 ° and ? 4 °C, which are influenced by water in the bud scales. The LTEs of the buds in the lower area of the shoot were higher as compared to the buds in the middle and upper area of the shoot. The LTE analysis clearly shows the frost adaptation of the latent buds which usually reaches a maximum by the end of January but a clear relation to the changing air temperatures could not be established. Histological and cytological analyses were used to test for frost damage in bud parts and for changes during the cold adaptation. A modified staining method was developed to differentiate the cells. During automn and winter the buds contained a lot of starch grains which dissolved at bud burst. A permeability barrier between bud pad and shoot primordia could not be found, however it could be directly shown, that a HTE causes no cell damage in the buds, while after the appearence of the LTE(s) a disintegration of protoplasts in primary and secondary buds could be found. This is a direct evidence that LTEs indicates the death of the eyes in the complex grapevine bud. If after the appearance of the HTE the buds were held one day at this temperature before further cooling, no LTEs would appear. This and similar observations during the frost storage of grapevine cuttings is discussed in terms of the (harmless) ice formation in the bud base at moderate minus temperatures which would result in a freeze drying effect due to the lower water potential of the bud pad (in comparison to the non frozen eyes) and a further increase of the frost resistance of the growing points. If frost adapted grapevine shoots from the field were kept at 20°C deacclimation occurred after about 10 days. Accidentally wetted buds showed exotherms above ?4°C. In these buds and the watering water ice nucleating bacteria (Pseudomonas fluorescens) could be found.
Molecular evidence of intraclonal variation and implications for adaptational traits of grape phylloxera populations (Daktulosphaira vitifoliae, Fitch)
(2007) Vorwerk, Sonja; Blaich, Rolf
Grape phylloxera (Daktulosphaira vitifoliae Fitch; Homoptera: Phylloxeridae) is an economical important insect pest of grapevine (Vitis spp.) worldwide. The insect was introduced with contaminated plant material from North America in the 1850s and spread rapidly across all European viticultural regions. In the 19th century, nearly three-forths of the ungrafted and highly susceptible European grape species were destroyed by the insect pest. European viticulture did not recover until the development of grafting, combining European Vitis vinifera varieties with resistant rootstocks, bred from American Vitis species. Grape phylloxera is still present in viticulture. Today, grape phylloxera populations mainly persist in abandoned vineyards and rootstock nurseries. Grape phylloxera populations seem to be variable in terms of genotypic composition and host adaptability. The lifecycle described by Fitch (1854) and others in the 19th century does not seem to match actual conditions anymore. This thesis aimed at redefining the genetic structure of European grape phylloxera populations by employing genetic markers. It was shown, that the insect has turned away from its classical holocycle and now mainly reproduces asexually, as already demonstrated for Australian grape phylloxera populations. Despite asexual reproduction, all examined populations revealed a high grade of genotypic diversity. The reports on the emergence of new and more aggressive strains raised the question, how a population composed of asexually reproducing organisms would change and adapt to such an extent. Using a multilocus marker system, eight single founder lineages were genetically monitored over at least 15 generations. All lineages revealed a high grade of intraclonal variation. Sequencing of polymorphic fragments showed, that the genetic variation was not due to contaminating plant or bacterial DNA, but was due to variation within the insect genome. Furthermore, mutations occured already in early generations and were not observed to accumulate in later generations. Mutations were rather generated constantly and only few mutation specific markers were identified to be stable over all following generations. The here documentated genetic variation reveals the great adaptational potential of this insect pest. The adaptability of single founder lineages was further assessed by measuring physiological parameters in single isolation chambers in the greenhouse. Parameters as the number of surviving individuals per generation, the number of eggs or the number of ovarioles per generation exposed differences in performance among the lineages and also within the lineages a high grade of intraclonal variation. A direct correlation of specific multilocus markers and particularly adapted individuals or lineages was not possible in this assay. Two markers, though, were observed to occure in several lineages which performed well on the new host plant. These markers may be a first step to the development of adaptation-related markers and need to be tested on further populations and host plants. When analysing intraclonal variation, the question of putative contaminating factors within the system arises. Symbiotic bacteria occuring in nearly all aphid species certainly are the first to be suspected as a source of genetic variation among single individuals tested. Endosymbiotic bacteria, as Buchnera aphidicola in other aphid species, influencing nutritional condition and fitness of the insect population, were not identified in D. vitifoliae. A bacterium, closely related to Pantoea agglomerans, however, was identified in several grape phylloxera populations, using universal 16S rDNA primers and later specifically developed markers, which were also employed for in situ hybridization. The bacterium was localized in the salivary pump of D. vitifoliae. PCR analysis of in vitro reared populations revealed that the bacterium is present in root- and leaf-feeding parthenogenetic populations of grape phylloxera and, moreover, seems to be transmitted from generation to generation. In other insect species, this bacterium has been demonstrated to produce antifungal and antibacterial substances, which were also found in first in vitro tests with grape phylloxera associated bacteria. The insect may benefit from the antagonistic potential of these bacteria. P. agglomerans may be a further participant in the certainly complex interaction of grape phylloxera and grapevine. This thesis represents a broad approach to elucidate the development of grape phylloxera populations in Europe. Using new molecular marker systems, it has become possible to gain more information on the genetic structure of the insect and its adaptational potential. The predominant clonal reproduction mode of the insect confronts grapevine breeders and pest management with the task to continously develop new resistant rootstocks and to keep up with new pest management systems.
Untersuchungen zur Abundanz der Reblaus (Dactylosphaera vitifolii Shimer) und zur Nodositätenbildung in Abhängigkeit von Umweltfaktoren
(2000) Kopf, Andreas; Blaich, Rolf
The aim of the examinations was to investigate the abundance of Phylloxera (Dactylosphaera vitifolii Shimer), the occurrence of different biotypes of Phylloxera, the reaction of rootstocks to the infestation by Phylloxera and the influence of abiotic environmental conditions on the interaction between insect and plant. To investigate this interaction galls on rootlets (nodosities) and leaf galls were examined. The abundance of Phylloxera and the issue of the holocyclical reproduction in the wine region palatinate were evaluated in a field monitoring. In a special field trial the occurrence of different stages of Phylloxera and their damages on the rootstock were registered. With a dual aseptical in vitro system Phylloxera of different origins were examined on their aggressiveness to different varieties of rootstocks. In pot trials the influence of the type of soil and the effect of N-fertilization on the development of nodosities were investigated. The results of the examination show that Phylloxera can be found in nearly every part of the palatinate and that the improper cultivation of grafted rootstocks promotes the spreading of Phylloxera. Through shoots of rootstocks ? as they can be found in vineyards run wild - a holocyclical development of Phylloxera is made possible under appropriate climatical circumstances. Fitness, population dynamics of Phylloxera and the number of nodosities caused by the insects are correlating with their adaptation to a host rootstock. Pot studies have demonstrated that Phylloxera populations develop better in clay soil than sandy soil. High densities of Phylloxera in combination with a lack of N-supply increase a growth depression on grafted roots. It could also be proved that N-fertilization reduces the Phylloxera populations and the development of nodosities up to 98 %.
Untersuchungen zur physikalischen Kartierung des Genoms der Weinrebe
(2000) Böhm, Andreas; Blaich, Rolf
In this study research on physical mapping of the grapevine genome was done and a method for preparation of high molecular weight DNA from Vitis-protoplasts was established. In the first part of the project the usefulness of megarestriction-fragments for physical mapping in different grapevine-varieties was analyzed. Hybridization experiments with a probe for repetitive DNA showed that most of the restriction fragments were only about 200 Kb in length with a maximum of 400 Kb. Due to the distance of 300 Kb/cM in the genome of Vitis most fragments only cover a distance of less than 1 cM. For this reason physical mapping with megarestriction-fragments would be less successful. As an alternative strategy for physical mapping a genomic BAC-library was constructed for the variety 'Vidal blanc' which is less sensitive to fungal pathogens. 800 BAC-clones with an average insert size of about 49 Kb have been randomly picked and analyzed. After transforming the complete ligation-mixture 30000 single BACs are expected. They represent more than 3-fold genomesize of Vitis and each single-copy sequence would be contained in the library with a probability of 95 For a first screening of the partial library specific probes for genes from the metabolism of plants or for genes with correlation to pathogen resistance have been developed. The amplification of partial sequences from these Vitis-genes was done with specific oligonucleotides. The PCR-products have been cloned and sequenced. A special probe specific for chloroplast-DNA was used to detect BACs with inserts from the genome of chloroplasts. As a first result of colony-hybridization experiments eight clones with inserts of chloroplast-DNA could be identified. One BAC-clone contains a gene similar to an osmotin-like protein.