COL5 is a circadian-regulated gene that controls flowering time M.Sc thesis Plant and environmental sciences Table of contents: Abstract: 3
Introduction: 4
Circadian rhythms: 4
The circadian system: 5
Flowering initiation in Arabidopsis: 6
Circadian clock and photoperiodism: 7
CONSTANS (CO) and Flowering Locus T (FT): 8
CO and CONSTANT LIKE (COL) family genes: 9
Results: 11
COL5 is a circadian clock regulated gene that controls flowering time: 11
Identification of homozygous col5 plants: 11
COL5 expression under diurnal condition: 13
COL5 expression is controlled by the circadian system: 14
COL5 is unlikely to be involved in function of the circadian clock: 16
COL5 is a positive regulator of light signaling: 17
COL5 mutants have a low rate of germination: 20 Overexpression of COL5: 22
COL5 protein localization: 23
Discussion: 24
COL5 is a circadian regulated gene: 24
COL5 regulates flowering: 24
COL5 has homology and may share functional redundancy with other COL members:
5 COL5 may act in Arabidopsis as Hd1 in rice:
5 COL5 regulates other light dependent developmental pathways: 26
col5 mutants are hyposensitive to red light: 26
Materials and Methods: 28
Arabidopsis growth-. 28
DNA extraction-. 28
Identification of homozygote mutants-. 29
Flowering time experiments-. 29
Circadian and diurnal experiments-. 29
RNA extraction-. 30 Northern blot preparation-. 30 Hybridization with radioactive labeled probes-. 30 Real-Time PCR analysis-. 30 Hypocotyl and roots elongation measurements-. 31
Germination rate experiment-. 31
Cloning COL5 into an over expression vector-. 32
Bacteria growth-. 33
E.coli and Agrobacteria transformations-. 34
Plant transformation-. 34
Checking for COL5 mRNA levels in over-expression lines-. 34
Reference: 35
Abstract:
In order to adapt to daily environmental changes plants have an endogenous clock system with a period of about 24 hours called a circadian clock.
The circadian clock system is composed of an environmental input signal pathway, an oscillator and an output pathway. The output pathway regulates many aspects of a plant's development and physiological processes including flowering time via the photoperiodic pathway. The timing of the transition to flowering is very important for plant development. So far four major pathways that regulate flowering have been described: the photoperiod pathway, the autonomous pathway, the gibberellin pathway and the vernalization pathway (Koornneef et al., 1998). These pathways monitor the developmental state of the plant and its environmental conditions. CONSTANS (CO) is an important output gene that regulates flowering in the photoperiodic pathway, integrating the circadian clock and light signals to control flowering time. In my work, I have identified CONSTANS-LIKE 5, a member of the CONSTANS-LIKE gene family. I show that COL5 is an important regulator, not only of flowering, but also of other light- regulated developmental pathways.