Characterization of Transcription Factor genes responsible for conferring cold tolerance in B. napus

다국어 초록 (Multilingual Abstract)

Brassica napus is one of the most important oilseed crop in the world with a major contribution to both agriculture and industrial sector. The production of rapeseed is diminished by various abiotic and biotic factors. In temperate regions like Korea cold stress is one of the major factors hampering the production of rapeseed. Cold stress impose several molecular and biochemical changes at the cellular level affecting the overall growth of plant. These cellular mechanisms have been studied a lot previously but still require a deep study for crop improvement to withstand cold-stress. Transcription factors are the regulatory switches in the pathways of cold-stress response. Targeting transcription factor gene can control the gene induction mechanism. In this study the B. napus plants were subjected to cold stress at various temperature. The total RNA were harvested from the cold-treated plants. Using the cold-treated RNA as template cDNA were synthesized.900 cold-responsive genes were downloaded from public database and sorted transcription factor related 90 genes from them. After desgining gene specific primers on 90 TF genes, we analysed their expression. Based on their expression we finally selected 20 genes for further studies.These genes includes transcription factors from various families such as MYB, Heat-shock proteins and Zinc-finger proteins. These TFs genes can be used for future studies and experiments. Secondly, I specifically focussed on GATA transcription factor genes in Brassica napus. The GATA transcription factors belong to the Zinc finger group of proteins and previous studies suggests their possible involvement in cold-stress pathways. For our study we used cold tolerant B. napus cultivar Naehan and Tamra and cold-suceptible cultivar Halla and Tammi. We downloaded 16 GATA TF genes from public database and constructed a phylogenetic tree including GNC and GNL from Arabidopsis. Based on the phylogenetic analyses the GATA TF genes were divided into four groups namely GATA 1-1, GATA 1-2, GATA 2-1 and GATA 2-2. We designed primers on consensus sequences of four GATA gene groups. We carried out expression analyses using cold-treated cDNA as template. GATA transcription factor genes showed variable expression under different temperature. Among four GATA 2-1 showed most promising results. The variable expression of GATA TF genes under cold stress provides a hint of their involvement in cold-response scenario and leaves us with questions that can serve as base for future studies.

목차 (Table of Contents)

• Acknowlegement……………………………………………………………………………………...…i
• Contents…………………………………………………………………………………………………iiList of Table…………………………………………………………………………………………….iv
• List of Figures…………………………………………………………………………………………...v
• Abstract……………………………………………………………………………………….............viii
• I. Introduction ………………………………………………………………………………………1
• 1. The Brassicaceae family………………………………………………………………………......1
• 1.1 Genus and species……………………………………………………………………………..1
• 1.2 Genome………………………………………………………………………………………..2
• 2. Brassica napus………………………………………………………………………………….....2
• 2.1 Taxonomy/ Genome…………………………………………………………………………..2
• 2.2 Plant morphology……………………………………………………………………………..3
• 2.3 Cultivation………………………………………………………………………………….....4
• 2.4 Economic importance…………………………………………………………………………7
• 2.4.1 Food and Feed………………………………………………………………………….....7
• 2.4.2 Industry and agricultural importance……………………………………………………..7
• 3. Rapeseed production constraints……………………………………………………………….....7
• 3.1 Biotic stress……………………………………………………………………………...……..7
• 3.2 Abiotic stress……………………………………………………………………………….......8
• 4. Low temperature stress……………………………………………………………………………9
• 4.1 Chilling stress……………………………………………………………………………….....9
• 4.2 Freezing stress………………………………………………………………………………...9
• 5. Mechanism of low temperature stress…………………………………………………………...11
• 5.1 Signal perception……………………………………………………………………………11
• 5.2 Signal transduction………………………………………………………………………….11
• 5.3 Functioning of COR genes………………………………………………………………….12
• 5.4 Post-translational events…………………………………………………………………….13
• 6. Approaches to develop low temperature resistance in plants……………………………………19
• II. Identification of genetic factors related to cold tolerance in Brassica napus
• 1) Abstract …………………………………………………………………………………….22
• 2) Introduction ………………………………………………………………………………...23
• 3) Material and Methods ……………………………………………………………………...26
• 4) Results ……………………………………………………………………………………...28
• 5) Discussion ………………………………………………………………………………….34
• III. Role of GATA transcription factors in Cold-tolerance
• 1) Abstract …………………………………………………………………………………….39
• 2) Introduction ………………………………………………………………………………...40
• 3) Material and Methods ……………………………………………………………………...42
• 4) Results ……………………………………………………………………………………...48
• 5) Discussion ………………………………………………………………………………….58
• IV. Conclusion and summary …………………………………………………………………….61
• References……………………………………………………………………………………...62