1. Front Cover.cdr - CORE

A B S T R A C T B O O K – A B S T R A C T S O F P O S T E R S
ENHANCING METHIONINE ACCUMULATION IN TOBACCO SEEDS EXPOSES A
PHYSIOLOGICAL LINK BETWEEN METHIONINE AND GLUTATHIONE AND ITS IMPACT ON
SEED GERMINATION
Itamar Godo, Ifat Matityahu, Rachel Amir
1 Laboratory of Plant Science, Migal Galilee Technology Center, Kiryat Shmona, Israel
2 Tel Hai Collage, Upper Galilee, Israel
E-mail: rachel@migal.org.il
Methionine is an essential amino acid whose level limits the nutritional value of crop plants; however, to
date, efforts to increase its content had limited success. We used tobacco plants to express a feedback
insensitive Arabidopsis cystathionine γ-synthase (AtCGS), the first committed enzyme in the methionine
biosynthesis pathway, under a seed specific promoter. Both methionine and total proteins contents of the
transgenic seeds were significantly increased, suggesting that CGS is a rate-limiting enzyme of methionine
synthesis in seeds, and that methionine availability limits seed protein synthesis. AtCGS expression altered
the protein profile and enhanced the expression of several methionine rich proteins. In the transgenic
seeds the amounts of glutathione (GSH) and cysteine, a precursor for methionine and GSH, were reduced,
suggesting that methionine accumulates at the expense of GSH. Although these methionine -enriched, low
GSH seeds, germinated slower than wild type, adult plants had no phenotype indicating that this effect is
limited to seeds. The delayed germination could be reversed by application of GSH. In addition to an
important step toward the development of high methionine food crops, this work contributes to the
understanding of methionine metabolism, its interactions with GSH and cysteine metabolism and their roles
in seed germination.
GENETIC ENGINEERING OF CAROTENOIDS BIOSYNTHESIS IN PHAEODACTYLUM
TRICORNUTUM
Ulrike Eilers, G. Sandmann, C. Büchel
Goethe-Universität Frankfurt, Frankfurt am Main, Germany
E-mail: u.eilers@sciencemail.org
Carotenoids are produced by all photosynthetic organisms and take part in light harvesting as well as in
photoprotection. Their antioxidative character and other functions are reasons for their important role in
the humans' nutrition. The high costs of synthetic carotenoid production give reason to find suitable hosts
for natural biosynthesis.
For a proof-of-principle we use the model organism Phaeodactylum tricornutum, a unicellular diatom
occurring in salt and brackish water. Since rather little is known about the enzymes involved in carotenoid
biosynthesis in diatoms we focus here on four endogenous genes, (Psy, Zep1- 3), coding for phytoensynthase
and zeaxanthin-epoxidases 1-3, respectively. Psy catalyses the entry and limiting reaction of the
carotenoids biosynthesis. Zep1-3 are coding for the enzymes responsible for the conversion of zeaxanthin
to violaxanthin.To investigate these four putative enzymes in P. tricornutum we cloned cDNA and genomic
DNA in order to identify their functions by complementing systems in E. coli.An interesting step for
industrial purposes is the carotenoid over expression. Therefore we will transform P. tricornutum with an
inducible Psy-construct to overcome the limiting entry reaction.Moreover, an additional gene (bkt), coding
for a ketolase, is cloned to set a bypass for astaxanthin synthesis without disturbing the physiology.
A GUIDELINE TO FAMILY-WIDE COMPARATIVE STATE-OF-THE-ART QRT-PCR ANALYSIS
EXEMPLIFIED WITH A BRASSICACEAE CROSS-SPECIES SEED GERMINATION CASE STUDY
Ada Linkies, Kai Graeber, Andrew Wood, Gerhard Leubner-Metzger
Albert-Ludwigs-University Freiburg, Faculty of Biology, Plant Physiology, Freiburg, Germany
E-mail: ada.linkies@biologie.uni-freiburg.de
qRT-PCR is a sensitive method to quantify gene expression. Even small differences in expression profiles
can be determined, given that the right precautions during data analysis are taken. One major concern is
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