15th International Conference on Arabidopsis Research - TAIR

T06-017
Investigation of the molecular basis of heterosis
using a combined genomic and metabolomic
approach
Hanna Witucka-Wall(1), Rhond C. Meyer(2), Otto Törjek(1), Eugenia Maximova(2),
Oliver Fiehn(2), Martina Becher(1), Anna Blacha(2), Michael Udvardi(2), Wolf-
Rüdiger Scheible(2), Thomas Altmann(1, 2)
1-University Potsdam, am Neuen Palais 10, 14469 Potsdam
2-Max-Planck Institute, am Mühlenberg 1, 14420 Potsdam
Heterosis, or hybrid vigour, refers to the phenomenon that progeny of crosses
between inbred varieties exhibit greater biomass, speed of development, and
fertility than the two parents. Although the effect of hybrid vigour has been
widely exploited in agriculture and breeding, very little is known about the
molecular mechanisms underlying heterosis. The widespread occurrence
of heterosis in the model plant Arabidopsis thaliana opens the possibility to
investigate the genetic basis of this phenomenon using the tools of genetical
genomics.
We established a Recombinant Inbred Line (RIL) population consisting of
ca. 400 F8 lines of the reciprocal combination C24 /Col-0, the F1 hybrids
of which exhibit significant heterosis for biomass production. The RILs are
being genotyped with 110 SNP markers to create a genetic linkage map.
QTL analysis is being performed using a modified design III with ca. 400 RIL
and their 800 test-crosses to each parent. The phenotypic characterisation
included the main heterotic trait biomass production, as well as traits potentially
contributing to the heterotic effect such as leaf size and morphology,
gas exchange parameters, and photosynthetic capacity. In soil grown plants,
size differences between parents and F1 were observed as early as 6 days
after sowing. To investigate possible differences in metabolic status between
parents and hybrids at the earliest developmental stages, we have began
implementing metabolite profiling using GC-MS (Gas Chromatography-Mass
Spectrometry) and LC-MS (Liquid Chromatography-Mass Spectrometry).
The metabolic analysis will be complemented by microscopic analysis of
germinating seeds from hybrid and parental lines. This will allow scrutiny of
differences in cell organisation, and/or numbers, which may contribute to
heterosis.
15 th <strong>International</strong> <strong>Conference</strong> on Arabidopsis Research 2004 · Berlin
T06-018
Comparative analysis of the FRIGIDA genomic region
reveals a recent transposition event in Arabidopsis
thaliana
Sandip Das(1), Christa Lanz(2), Stephan Schuster(2), Detlef Weigel(1, 3)
1-Dept. of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen,
Germany
2-Genome Center, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
3-Salk Institute, La Jolla, CA 92037, USA
Comparative genetic mapping analysis has been used extensively to study
and understand genome organization and evolution at the macro level,
however, due to limited marker density, exceptions to colinearity at the
microlevel will be overlooked. This limitation can be overcome by large scale
sequencing efforts. We are interested in patterns of sequence conservation
and divergence at loci controlling flowering time. Here, we present initial data
focusing on the region containing the FRIGIDA gene between Arabidopsis
thaliana, Arabidopsis halleri, Boechera (syn. Arabis) drummondii and Capsella
rubella. We shot-gun sequenced BACs containing the FRIGIDA gene from
all three species. An initial analysis reveals conservation of synteny between
the species that are being compared. This is in agreement with what has
been reported for other regions of A. thaliana and C. rubella. However, the
study also reveals that the present location of the FRIGIDA gene on top of
chromosome 4 in the Arabidopsis thaliana genome is a very recent event.
We are carrying out further analysis to map this transposition event on an
evolutionary time scale.
T06 Natural Variation and Comparative Genomics Including Genome