Calendar Name: seminars
Scheduled for: Thursday, June 13 2013, 11:00 - 12:30
Event text: Prof Philip Gilmartin
Plant Molecular Genetics
Faculty of Science
University of East Anglia
Norwich
Norfolk
UNITED KINGDOM
Details: �Floral heteromorphy in Primula: genetics, genomics and
gene identification�
ABSTRACT
J Li1, 2 . M. Webster1, 2, M. Smith1, 2, J. Cocker1, 2,
O. Kent1, 2, J. Wright3, D. Swarbreck3, M. Caccamo3, P.
M. Gilmartin1, 2
University of East Anglia 1, John Innes Centre 2 and The
Genome Analysis Centre 3, Norwich Research Park,
Norwich, UK.
Floral heteromorphy is an out-breeding mechanism that is
characteristic of, although not limited to, the
Primulaceae. The phenomenon was described in detail by
Charles Darwin, but first documented over a century
earlier. In Primula species, individuals develop one of
two forms of flower, known as pin and thrum. Pin
flowers are characterised by a long style that presents
the stigmatic surface at the mouth of the flower, and
contain anthers attached half way down the inner wall of
the corolla tube. Thrum flowers have a short style.
half the height of that found in pin flowers, and
anthers attached to the inner corolla wall at the mouth
of the flower. This reciprocal positioning of male and
female reproductive structures promotes insect-mediated
cross pollination. These developmental characteristics,
and other features of floral heteromorphy, including
differential pollens size, as well as a sporophytic
self-incompatibility system, are controlled by a
co-adapted linkage group known as the S locus. Pin
plants are homozygous recessive s/s; thrum pants are
heterozygous S/s.
With the objective of identifying the genes at the S
locus that control style length, anther height and
pollen size, we have taken a multifaceted approach
involving classical genetics, molecular genetics,
transcriptomics and genomics. We have identified and
characterised a number of genes and polymorphic markers,
as well as developmental mutations that are linked to
the S locus. Using these sequences and S locus-linked
mutant phenotypes we have developed a classical genetic
linkage map in Primula vulgaris, spanning the Primula S
locus and delineated by flanking markers. Subsequent
construction and screening of BAC libraries has enabled
us to generate a BAC contig spanning the S locus and to
identify pin and thrum specific BACs.
Transcriptomic analysis of pin and thrum plants has
identified morph specific floral transcripts, and
transcriptomic and genomic analyses of linked mutations,
including Oakleaf, sepaloid and Hose in Hose has been
used to probe the molecular basis of these phenotypes.
In addition to these analyses we have undertaken de novo
genome sequencing of Primula vulgaris to generate a
reference genome and have used genome sequencing of
individual parents and pools of pin and thrum progeny to
define polymorphic markers surrounding the S locus.
Comparative genomic analyses are underway based on de
novo sequencing of the four additional UK native
species; P. veris, P. elatior, P. farinosa and P.
scotica. We have, in parallel, undertaken a large scale
of plants derived from fast neutron bombarded P. veris
seed to identify long and short homostyle as well as
self compatible mutants.
We will present our most recent work arising from these
studies to highlight progress towards identifying the
genes that underpin Darwin�s descriptions of this
breeding system.
