The Arabidopsis Myb Genes MYR1 and MYR2 - Essay Example

Arabidopsis is a long day plant that flowers earlier than other plants in long day conditions than in short day conditions. In LD conditions flowering is affected by an increase in expression of the flowering locus T (FT). This gene expression is controlled by CONSTANS (CO). Under low light intensity, homozygous myr1 and myr2 mutants will flower and show an increase in petiole length, apical dominance and leaf angle. Analysis on the genetics of the mutants point out that myr1 and myr 2 phenotype need GA biosynthesis.

In determination of the functions of MYR1 and MYR2 roles in plant development and growth two independent T-DNA alleles for every gene. The T- DNA were evaluated and discovered that they eliminated full length expression of MYR1 and MYR2 in plants homozygous to every mutation. The homozygous myr1 and myr2 mutants happened to be identical to WT plants in relation to their leaf color, plant size and morphology. In SD conditions plants that had any of these alleles had an early flowering and this generally indicates that myr1 and myr2 had suppressive effects on flowering.

Additionally, flowering locust T was also needed by the Myr1 and Myr2 phenotype responsible for flowering and these mutants also demonstrated an interface with phyB-9 mutant. When Myr1 and Myr2 are over expressed, GA deficiency symptoms are shown which are then eliminated by use of gibberellic acid (GA1). When Myr1 and Myr2 were lost, there was a double boost in GA20ox2 expression and GA1 levels increased by 30%. Myr2 over expression caused a three time GA20ox2 decrease and 50% reduction in GA1 levels.

Therefore, it can be concluded that Myr1 and Myr2 ability to limit flowering and elongation of organs is slightly because of their destructive consequence on the bioactive GA levels. In this case, it is possible that the increase in expression for the GA negative regulators showed the property of having a shade avoidance phenotype. The role of MYR1 and MYR2 of affecting the GA2O0x2 expression could be the determinant for observed phenotypes and it is in the same line with research on GA2O0x2 genes that indicate their importance in regulating growth and fertility of the Arabidopsis plant.

This essay is based on a previous research done by several researchers. It will describe the result, outline the conclusion and give an insight on future work based on this research. In the result that has indicated that MYR1 and MYR2 have a role in plant growth and development, it is indicated that as light intensity became high, the phenotype became weak and double mutants of myr1 and myr2 produced fewer than WT, rosette leaves. In relation, vegetative growth and flowering time characteristic of the myr1 and myr2 mutants exhibited a similarity with phyB mutants.

When MYR1 and MYR2 are paralogous and the genes are co-expressed, lengthening of the vegetative period in SD conditions showed a weakening in the phenotype responsible for early flowering. Myr1 and myr2 that were early flowering under a LD environment was connected with more features that were not present in single mutants. They a longer petiole, lengthy hypocotyls and the leaves were more vertically oriented with a peak in apical dominance. This features show that the early flowering phenotype had been strengthened and that both myr1 and myr2 double mutants expressed the presence of MYR1 and MYR2 redundancy property which was not shown in the single mutant’s myr1 and myr2.

In addition it was discovered that MYR1 and M