Rubber,
Ricin, Poinsettias . . and Jumping Genes
Monday,
11 June 2007
Having recently published in the Holy
Grail of all scientific publications,
"Science," Dr. Kenneth Wurdack,
Assistant Curator of Botany, gave an invigorating
lecture titled, "Rubber, ricin poinsettias...
and jumping genes: Evolution of Euphorbiaceae,"
to jump-start Botany day.
Dr.
Wurdack cited several common economic
uses for the Euphorbiaceae, or "rubber"
family of tropical plants, including gloves,
tires and condoms, to orient students
to the diverse family, which includes
8-9,000 species!
Creating
a phylogeny of the Euphorbiaceae based
on DNA evidence, Dr. Wurdack showed students
the surprising relationships between seemingly
unrelated plant species. Rafflesia,
a unique parasitic plant which produces
the world's largest flower, at 1 meter
across, is in the family Rafflesiaceae.
Thought by early scientists to be a primitive
flower, Wurdack's phylogeny of the Euphorbiaceae
reveals that the Rafflesiaceae family
is nested within the Euphorbiaceae, the
latter a highly advanced family known
for small tropical flowers. The students
were fascinated by how quickly the Rafflesiaceae
evolved such huge flowers, and apparently,
so were Wurdack's peers in this scientific
research, as the Rafflesia story
made the cover of "Science."
Wurdack similarly wowed students with
his description of horizontal gene transfer,
i.e., gene transfer between sexually unrelated
species, in the Rafflesiaceae. Wurdack
described this discovery as somewhat of
an accident; he hadn't been looking for
horizontal gene transfer! Botany intern
and lecture host Emma Harrower
was excited by the "serendipity"
of his discovery of horizontal gene transfer
between Rafflesia and their host
plants.
Through
his phylogenetic analysis of the castor
bean plant, Ricinus communis, also
a member of the Euphorbiaceae, Wurdack
revealed the evolutionary history of the
toxin ricin. Ricin is a potent natural
poison derived from seeds of the castor
bean plant, and has been highlighted in
the news for fears of its potentially
deadly use by terrorists. The castor bean
is presently grown around the world but
Wurdack traced its origins to Asia using
a phylogenetic tree and discovered that
related plants had genes similar to ricin.
Dr. Wurdack's research revealed the importance
of phylogenetic analysis in understanding
the evolution of various groups of species
and looking at relationships between seemingly
dissimilar organisms.
-
Morgan Little
