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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<br />

Arabidopsis RNA polymerase II (RNAPII) C-terminal domain (CTD) phosphatases regulate stress-responsive<br />

gene expression and plant development via the dephosphorylation of serine (Ser) residues of the CTD.<br />

Some of these phosphatases (CTD phosphatase-like 1 (CPL1) to CPL3) negatively regulate ABA and stress<br />

responses.<br />

We isolated AtCPL5, a cDNA encoding a protein containing two CTD phosphatase domains (CPDs). To<br />

characterize AtCPL5, we analyzed the gene expression patterns and subcellular protein localization,<br />

investigated various phenotypes of AtCPL5-overexpressors and knockout mutants involved in ABA and<br />

drought responses, performed microarray and RNA hybridization analyses using AtCPL5-overexpressors,<br />

and assessed the CTD phosphatase activities of the purified AtCPL5 and each CPD of the protein.<br />

Transcripts of the nucleus-localized AtCPL5 were induced by ABA and drought. AtCPL5-overexpressors<br />

exhibited ABA-hypersensitive phenotypes (increased inhibition of seed germination, seedling growth, and<br />

stomatal aperture), lower transpiration rates upon dehydration, and enhanced drought tolerance, while the<br />

knockout mutants showed weak ABA hyposensitivity. AtCPL5 overexpression changed the expression of<br />

numerous genes, including those involved in ABA-mediated responses. In contrast to Ser-5-specific<br />

phosphatase activity of the negative stress response regulators, purified AtCPL5 and each CPD of the<br />

protein specifically dephosphorylated Ser-2 in RNAPII CTD. We conclude that AtCPL5 is a unique CPL family<br />

protein that positively regulates ABA-mediated development and drought responses in Arabidopsis.<br />

CALLUS INDUCTION AND FATTY ACID PROFILES OF JATROPHA CURCAS INDUCED CALLI<br />

ChongSiang Tee 1 , ThenSoong Siow 1 , Adelin Ting Su Yien 2<br />

1 Department of Biological Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, Kampar, Perak, Malaysia<br />

2 School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan, Malaysia.<br />

E-mail: teecs@utar.edu.my<br />

Jatropha curcas, a biodiesel production plant, is intensively cultivated in many countries. The main<br />

objectives of this study were to induce callus from various types of J. curcas explants and study the fatty<br />

acid content of the induced calli. In this study, different types of auxins at various concentrations were used<br />

to induce callus. In addition, fatty acid compositions and total oil content in the induced calli were also<br />

investigated. It was observed that 4 µM of picloram, 4 µM of dicamba and 2 µM of 2,4-D, cotyledon and<br />

petioles explants, respectively. For leaf explants, 2,4-D was used in combination with cytokinin to induce<br />

callus. Besides, embryogenic calli induced from cotyledon explants using MS medium containing 4 µM<br />

dicamba. The fatty acid analysis revealed that fatty acid compositions in the induced calli were similar to<br />

that of seed kernels particularly the fatty acid profile of embryogenic calli. Generally, induced calli had lower<br />

oil content than seed kernels. Among all types of induced calli studied, embryogenic calli had higher total oil<br />

content than non- embryogenic calli but significantly lower than the seed kernels.<br />

NEW PERSPECTIVE IN PLANT VITAMIN D PRODUCTION<br />

Daniele Silvestro 1 , Christina Fredslund 1 , Rie Bak Jäpelt 2 , Poul Erik Jensen 1<br />

1 Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark<br />

2 Division of Food Chemistry, National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark<br />

E-mail: dasi@life.ku.dk<br />

The presence of vitamin D compounds has been established in a few plant species and could represent an<br />

alternative source of vitamin D. Interestingly, the metabolic pathway leading to the formation of vitamin D<br />

in plants is basically unknown. The enzyme Δ5,7-sterol-Δ7-reductase (7DHCR) is known to catalyze the<br />

conversion of 7DHC into cholesterol in vertebrates while in plants a similar enzyme (DWARF5) converts the<br />

Δ5,7-sitosterol (7DHS) into sitosterol. The structure similarity should make possible the conversion of 7DHS<br />

into vitamin D (vitamin D5) by exposure to UV B light.<br />

To verify if this conversion is occurring in plants A. thaliana dwarf5 mutants have been exposed to UV B<br />

light. This mutant is accumulating Δ5,7-sterols (mainly 7DHS) due to a mutation in the Δ7-reductase and it<br />

displays a dwarf phenotype due to the down regulation of the brassinosteroid biosynthesis.<br />

Moreover two cDNA sequences highly homologous to A. thaliana DWARF5 were isolated from S.<br />

lycopersicum. The activity of the codified enzymes was assessed by enzymatic assay via expression studies<br />

in yeast and plant. The results on yeast made by GC-MS sterol characterization of the transformants<br />

82<br />

X X I V S P P S C O N G R E S S 2 0 1 1

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