MICROBOTRYUM
the evolutionary ecology of disease and genetic systems

Introduction: This is a portal to information on fungal pathogens in the genus, Microbotryum. These organisms and their interactions with plants in the carnation family (the Caryophyllaceae) are important research tools for many fields of biology, including genomics, host-pathogen interactions, and evolutionary ecology. A broad international community is working to advance this system, in terms of research discoveries, education, and training of future scientists.

 

Protocols & Resources: under construction (2016)

Microbotryum Tetrad Collection

Field Protocols

     Collecting Microbotryum Samples

     Mapping Local Populations

     Refinding Marked Individuals

     Experimental Populations

 

Lab Protocols: Organismal

     Inoculating Plants

     Mating Type Bias Assay

     Greenhouse Soil Mix

     Storage of Cultures

     Meiotic Tetrad Isolation

     Testing Mating Types

 

Lab Protocols: Molecular

     Isolation of DNA

     Electrophoretic Karyotypes

 

History:

    The fungus Microbotryum violaceum causes anther-smut disease of plants in the Caryophyllaceae (the Pink Family). This fungus has been of scientific importance since at least the mid 1700’s.

    Carl Linnaeus, in his Hortus Cliffortianus (1738), mistook a specimen of the plant Silene latifolia with anther-smut disease as representing a new species, with flowers fully covered in black powder. In 1760, the rather advanced work of Jean Baptiste Aymen ("Recherches sur les progres et la cause de la nielle" Memoires de mathem. et de phys. 3:68-85) displayed a surprising knowledge of anther-smut. Perhaps through Aymen’s correspondence with Linneaus, the infected Silene latifolia specimen was reassigned by the time of Systema Naturae 12th edn. in 1767.

    In some important areas, there remained confusion as to the nature of Microbotryum. In 1821, the foundational work of Elias Fries (Systema Mycologicum, vol. 1, pp xxv-xxvi) debated the source of dark powdery anthers, saying they simply contained inviable pollen and that any associated fungus was of heterogenic origin. However, Anton de Bary, in 1853 (Unterauchungen uber die Brandpilze und die durch sie verursachten Krankheiten der Pflanzen. Berlin) used Microbotryum as one of his examples demonstrating that fungal parasites are the causes of disease rather than symptoms.

    By the late 1800’s, the curious effects of anther-smut disease upon sex expression in plants was well know. Microbotryum replaces the pollen in anthers with fungal spores, and even female plants take on a male-like appearance with large anthers and aborted ovaries.  This unusual development was noted by the important suffragist (and scientist) Lydia E. Becker, who corresponded several time with Charles Darwin before presenting a paper in 1869, "On alteration in the structure of Lychnis diurna, observed in connexion with the development of a parasitic fungus" (Report of the 39th meeting of the British Association for the Advancement of Science, p. 106).  Darwin added a note on the 1863 letter from Becker, "The purple anthers  a fungus—".  What came to be known as "parasitic castration" by Microbotryum was studied in Ant. Magnin’s 1888 "Sur l'hermaphrodisme parasitaire et le polymorphisme floral du Lychnis dioica" (Comptes rendus 107: 663-665), as well as by many others who used anther-smut as a model to manipulate plant sexual dimorphism.

    With the rediscovery of Mendel’s Laws in the early 1900’s, mycology became more directed toward genetic studies, and again, Microbotryum was used to make significant contributions.  As part of Hans Kniep’s earliest work on sexual compatibility (1919, Untersuchungen uber den Antherenbrand (Ustilago violacea Pers.). Ein Beitrag zum sexualitatproblem. Z. Bot. 11:257-284), Microbotryum was used to demonstrate bipolar mating types. Most recently, the first dimorphic sex chromosomes to be discovered in fungi were found in Microbotryum, and this system is continuing to provide intresting insights into the evolution of sexual systems. In several other areas, anther-smut disease is being actively studies as an empirical model: molecular mechanisms (e.g. the long-running "Genetics of Ustilago violacea" series); taxnomy (e.g. the latest in a long history of revisions has moved Microbotryum between Orders of fungi!); ecological and evolutionary disease dynamics (e.g. Microbotryum presents a tractable and low-risk system for a great many experiments addressing disease in natural populations).

 

 

 


Created under supported from NSF award 310042
(Link to M. E. Hood homepage - Amherst College)