Title Page
Contents
ABSTRACT 8
I. Introduction 10
1. Shade avoidance response 10
2. Regulatory function of homeodomain-leucine zipper (HD-Zip) genes during plant development 11
3. Plant hormones during shade avoidance 12
II. Materials and methods 16
1. Plant materials and growth conditions 16
2. Phytohormone inhibitor treatment and hypocotyl measurement 16
3. Transient gene expression assay 17
4. Quantitative real-time PCR 17
5. Dual luciferase assay 17
6. Yeast two-hybrid assay 18
7. Primers used in this study 18
III. Results 20
1. NPA and PAC treatment inhibit hypocotyl elongation of Arabidopsis seedling during shade avoidance response 20
2. GA biosynthetic genes are induced by shade treatment 22
3. ATHB2 and TCP13 can promote GA20ox2 expression 24
4. ATHB2 binds to GA20ox2 promoter 26
5. TCP13 interacts with GAF1 in yeast 29
IV. Discussion 31
V. References 33
ABSTRACT IN KOREAN 41
Figure 1. Light and hormone signaling pathway regulate cell elongation 14
Figure 2. Effect of NPA and PAC on hypocotyl lengths of Arabidopsis thaliana... 21
Figure 3. Expression pattern of GA biosynthetic genes under W and W+FR in... 23
Figure 4. Role of ATHB2 and TCP13 in GA20ox2 expression 25
Figure 5. Luciferase assay using different lengths of GA20ox2 promoter 28
Figure 6. Interaction of TCP13 with GAF1 proteins 30