Julius Kühn and cultivated crops: A historical review of his work commemorating the 100 anniversary of his death

Am 14. April 1910 verstarb der Landwirt und Wissenschaftler Prof. Dr. Julius Kühn in Halle (Saale). Sein ungeheurer Schaffensdrang, seine immerwährende Arbeitslust aber auch unendliche Herzensgüte machten ihn zu einer herausragenden Persönlichkeit und zum Vorbild tausender Studenten, die ihn liebevoll „Vater Kühn“ nannten. Er gilt als Begründer des agrarwissenschaftlichen Studiums, hat die „Prüfungsanstalt für landwirtschaftliche Maschinen und Geräte“ aufgebaut, sich für die Gründung pflanzenpathologischer Anstalten – quasi der Vorgängerorganisation des Julius Kühn-Instituts – eingesetzt und schuf mit der „Versuchsstation für Nematodenvertilgung Halle“ den Vorläufer des amt­lichen Pflanzenschutzdienstes in Deutschland. Damit hatte Julius Kühn die erforderlichen Strukturen geschaffen, landwirtschaftliche Forschung zu betreiben, Lösungen zu erarbeiten und diese in der Praxis zu etablieren. Wie kaum ein Zweiter hat Julius Kühn die landwirtschaftliche Entwicklung in Deutschland vorangetrieben. Unter anderem etablierte er das landwirtschaftliche Versuchswesen, führte die Drillsaat in Schlesien ein, erkannte in dem Rübenzystennematoden Heterodera schachtii den wahren Verursacher der Rübenmüdigkeit und beschrieb bedeutende Schaderreger, wie Ditylenchus dipsaci und Rhizoctonia solani. Sein wegweisendes Werk Die Krankheiten der Kulturgewächse, ihre Ursachen und ihre Verhütung gilt als das weltweit erste phytomedizinische Lehrbuch. Bis heute werden die Arbeiten Julius Kühns in verschiedensten Institutionen fortgeführt, so auch im Julius Kühn-Institut, Bundesforschungsinstitut für Kulturpflanzen, dessen Namensgeber er ist. Anlässlich des 100sten Todestages von Julius Kühn soll dieser Beitrag an seine wegweisenden Arbeiten auf dem Gebiet der Kulturpflanzen erinnern.On April 14, 1910 the farmer and scientist Prof. Dr. Julius Kühn passed away in Halle, Germany. His enormous scientific productivity and creativity along with his ongoing enthusiasm and kind-heartedness made him an outstanding personality and an archetype for thousands of his students which called him fondly “Father Kühn”. He established agricultural sciences at the university, co-launched the “Institute for inspection of agricultural machinery and equipments”, postulated the need for phytopathological Institutes – such as the Julius Kühn-Institut – and established the “Experimental Station of Nematode Control Halle”, predecessor of the Plant Protection Service in Germany. Hence, Julius Kühn created the infrastructure to study the mechanisms of modern agriculture, develop solutions and established them in praxis. Unlike any other person, Julius Kühn promoted agricultural development in Germany. He established modern field experimentation, introduced the drill seed technology in Silesia, discovered the beet cyst nematode as origin of the beet replant disease and described important plant pathogens such as Ditylenchus dipsaci and Rhizoctonia solani. His great work Die Krankheiten der Kulturgewächse, ihre Ursachen und ihre Verhütung is considered to be the first text book in phytopathology worldwide. Today, his work is continued by several institutions such as the Julius Kühn-Institut, Federal Research Institute for Cultivated Plants, which is carrying on his name. The 100 year anniversary of his death is commemorated by reviewing some of his pioneering research on cultivated plants

Conservation and Diversity of Seed Associated Endophytes in Zea across Boundaries of Evolution, Ethnography and Ecology

Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate, Enterobacter asburiae, was able to exit the root and colonize the rhizosphere. Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration

Phytomedizin

Dieses Lehrbuch liefert den kompakten Begleitstoff für die phytomedizinischen Lehrveranstaltungen im Bachelorstudium. Zahlreiche Illustrationen und Übersichtsdarstellungen sowie Merksätze und Prüfungsfragen unterstützen die Vermittlung der notwendigen Kenntnisse. Der Schwerpunkt dieses Buches liegt auf der Vermittlung von Grundlagen der vielfältigen abiotischen und biotischen Ursachen von Pflanzenschäden sowie der Methoden und Strategien zu ihrer Bekämpfung im Rahmen des Pflanzenschutzes. Weiten Raum nimmt deshalb die Darstellung der Vielfalt und Lebensweise der Schaderreger sowie der großen Breite von Verfahren und Präparaten des Pflanzenschutzes und ihrer Anwendung ein. Hinzu kommen Aspekte wie der integrierte Pflanzenschutz, der biologische Pflanzenschutz und die gesetzlichen Regelungen des Pflanzenschutzes einschließlich der Risikobewertung bei der Zulassung und Anwendung von Pflanzenschutzmitteln. Allgemeine Grundlagen werden auch zur Interaktion zwischen Kulturpflanzen und Schadorganismen vermittelt.</jats:p

Bacterial endophytes in cotton: location and interaction with other plant-associated bacteria

Investigations were conducted to determine if biological control agent Pseudomonas fluorescens 89B-61 could colonize cotton tissues systemically and if internal colonization by a known endophytic bacterium, Enterobacter asburiae JM22, was influenced by the presence of other plant-associated bacteria. Following seed treatment, Pseudomonas fluorescens 89B-61 colonized cotton roots both externally and internally at mean population densities of 8.7 × 105 CFU/g and 1.1 × 103 CFU/g, respectively. However, bacteria were not detected in cotyledons, leaves, or stems. After inoculation onto leaves, Pseudomonas fluorescens 89B-61 established a mean internal population density of 1.6 × 104 CFU/g leaf tissue. Following stem injection, Pseudomonas fluorescens 89B-61 did not colonize roots or leaves. Pseudomonas fluorescens 89B-61 was localized on the root surface concentrated in grooves between epidermal cells, below collapsed epidermal cells, and in intercellular spaces close to the root epidermis, as identified by immunogold labeling of the bacterial membrane. Combined application of E. asburiae JM22 with another endophyte, Paenibacillus macerans Tri2-10, resulted in significantly lower internal populations of E. asburiae JM22 compared with treatment with E. asburiae JM22 alone. However, when coinoculated with a rhizosphere colonist, Micrococcus agilis strain 2RD-11, the colonization density of E. asburiae JM22 was not negatively affected. The results suggest that the internal colonization of cotton by bacteria with biological control activity may be an important aspect in their capacity to protect host plants against plant pathogens. The extent of internal colonization was shown to be influenced by other bacterial colonists.Key words: endophytic bacteria, location, interaction, cotton. </jats:p

Immunological detection and localization of the cotton endophyte <i>Enterobacter asburiae</i> JM22 in different plant species

Immunological methods were used to study the colonization of internal tissues of different plant species by the endophytic bacterium Enterobacter asburiae JM22. Polyclonal and monoclonal antibodies applied in enzyme-linked immunosorbent assay (ELISA), dot blot assay, tissue printing, or immunogold labeling were sensitive and specific enough to detect JM22 in plant tissues. Detection limits were 1.0 × 103 colony-forming units (CFUs)/mL for tissue printing, 1.0 × 104 CFUs/mL for ELISA and 1.0 × 105 CFUs/mL for dot blot assay. Polyclonal and monoclonal antibodies showed a positive immunological reaction with nearly all tested Enterobacter spp. In contrast with polyclonal antibodies, the monoclonal antibodies differentiated Enterobacter spp. and closely related genera like Pantoea or Serratia. Other bacterial genera, plant sap from nontreated field-grown crops, and soil solutions did not react with the antisera. When applied as a seed treatment, JM22 colonized roots, stems, and cotyledons of bean, cucumber, and cotton plants. Fourteen days after inoculation of cotton cotyledons or leaves, JM22 was detected inside the inoculated plant tissue and the bacteria moved to the roots. JM22 reached concentrations up to 1.0 × 105 CFUs/g in roots, 1.0 × 104 CFUs/g in stems, and 1.0 × 103 CFUs/g in cotyledons or leaves. Population densities of JM22 varied between the different plant species, being highest in bean and lowest in cotton. JM22 was detected with ELISA in different plant growth media. While sand, ground clay, and loamy sand showed high and comparable ELISA readings, the extinctions of sandy loam and Promix were significantly lower than the ones of the other three growth media, indicating a strong influence of soil mixes on immunological reactions. JM22 showed an intensive gold label in drop preparations of bacterial suspensions in phosphate buffer, plant sap, and ultrathin sections of plant tissue. After seed treatment, the bacteria were located on the root surface, concentrated in grooves between epidermal cells, below collapsed epidermal cells, within epidermal cells, and inside intercellular spaces in the root cortex close to conducting elements. Inoculation of leaves or cotyledons resulted in the occurrence of many gold labeled cells of JM22 on the petiole surfaces. Enterobacter asburiae colonizes different plant species and establishes endophytic populations in various tissues.Key words: immunology, endophytic bacteria, colonization, localization, plant species. </jats:p