Master of Science (MSc)
Faculty of Science
Several early-flowering flax (Linum usitatissimum L.) lines were derived from treatment of germinating seeds with 5-azacytidine in 1990. These lines are also shorter, have fewer leaves, and their DNA is hypomethylated, relative to their corresponding controls. The work presented in this thesis used early-flowering and control lines of the Royal (R) flax genotype, and the Large (L) flax genotroph. Firstly, levels of cytosine methylation were measured over a 24-hour period in the early-flowering line RE2 and its control (RC), using an HPLC method. Secondly, to determine the response of the flax lines to short-day conditions, control and early-flowering lines from both L and R were grown in either 8-hour-day or ambient, longday light conditions, and were compared in a number of aspects of development. Thirdly, primers for five putative flax flowering genes (SOC1, COL, ADG1, GAI, and AP1) were designed and a semi-quantitative PCR method was used to establish developmental expression profiles in leaves and shoot tips of RC and RE2 in order to detect differences in expression that may have resulted from the original demethylation treatment. Methylation was found to remain constant in RC and RE2 over the 24-hour period in all three tissues examined. In the short-day experiment the early-flowering lines differed from controls in a number of parameters, but the most notable were that the treatment delayed flowering and increased the number of leaves produced in all lines, but had less of an effect on the early-flowering lines. Expression patterns for the five genes examined indicated that they are all expressed in both leaves and shoot tips, and for most genes there was no indication that their expression had been altered by the demethylation treatment. However, AP1 expression was higher in leaves of RE2 than those of RC, and was found to reach higher levels in the buds of RE2 than those of RC. These expression differences may be the result of demethylation of a gene upstream of API that was affected by the demethylation treatment. The results of these experiments further demonstrate the differences between the early-flowering lines and their controls, and will help elucidate the genetic basis for these differences.
House, Megan A., "Molecular Studies of 5-Azacytidine-Induced Early-Flowering Lines of Flax" (2010). Theses and Dissertations (Comprehensive). 966.