Salinity’s Effect on Arabidopsis Wild Type and Mutant StandsRDR6 and DCL4

Control

Wild Type DCL4 RDR6 Wild Type DCL4 RDR6

Treatment

Abstract

The goal of this experiment is to determine the phenotypic influences the genes RDR6 and DCL4 will have on the Arabidopsis plants. By adding an environmental stress to these plants, it will be determined whether or not RNA silencing has occurred; after observation and comparison of the control group and stressed group, the phenotypic differences can be detected. These phenotypic differences may represent how the mutant strands respond differently to the environmental stress in comparison to the control groups in either an advantageous or disadvantageous form. Arabidopsis is the model plant of biology. It is studied by scientists all over the world because of its ability to be compared to other plants. This plant can easily be related to other plants when working with genetics because it is found in most temperate places around the world. Common crops also grow in temperate areas, indicating that most plants respond to stress similarly to the Arabidopsis. This allows us to characterize many foods and produce. We study Arabidopsis because its small size makes it easy to grow and study in large quantities. Many generations and mutations can be grown and controlled in a small area. In comparison to experimenting on a large amount of space, observing the stress on a smaller area is much more efficient. The Arabidopsis genome is also conveniently small and the whole genome has already been sequenced. Arabidopsis plants have 108 base pairs, 25,000 genes, and 5 chromosome pairs. Compared to a human, the genome is smaller and the sequences are more adequate to detect. Ultimately, the Arabidopsis plant has an advantage in its life span. The Arabidopsis plant has a very short life span, allowing us to study generational changes relatively quickly. This is helpful to ascertain all the changes a plant experiences in its life time. In this experiment, the mechanism of forward genetics is used. When the experiment was started, the phenotype could be observed, but the goal was to replicate and eventually find the gene that is being dealt with, or the gene that is lacking in the case of RNAi(RNA interference). RNA interference occurs after the RNA has left the nuclear membrane. Transcription, the process of selecting necessary nucleotide bases(exons) and removing unnecessary bases(introns) to convert DNA to RNA, has already occurred by this point. When the strip is ready to leave the cytoplasm , a cap and tail are added. mRNA is effected first. RNAi stops translation, the change from being a nucleotide sequence into a protein to express a certain gene. RNAi is also a part of a positive evolutionary change. First, it can work as a gene regulation for eukaryotes. In the case of our Arabidopsis experiment the DCL plant, the dicer, is the mutation in this research and development. The dicer gene creates an enzyme in response to stress that fragments double stranded DNA strands into smaller pieces. These double stranded DNA pieces are produced by the RDR gene, which stands for RNA dependent polymerase. Once the enzyme has “diced” the DNA, it is called siRNA. siRNA can then bind to a complex that has the appropriate active site, RISK. When siRNA is bound to RISK it causes the entire complex to combust. This explosion in turn leads to the interference of the gene that was once available to the plant.

Methods and Data Analysis

For this experiment the typical watering scheduled was followed which entails separate watering for the control and stressed groups of Arabidopsis. Each group received half a gallon and one teaspoon of fertilizer of water both Monday and Thursday, but the stressed group, in addition, received one half of a teaspoon which was dissolved in the water. The plants were thinned on 3/19/09, the same day in which the salinity treatment commenced. Approximately every ten days, the size of leaves in each pot were measured by width, and qualitative pictures were taken under a microscope, presenting that the mutant plants, DCL4 and RDR6, did not mature as healthily and rapidly as the control plants. This regiment was followed until the final stage of the Arabidopsis reproductive cycle approximately six weeks from the 19th of March.

Effects of Salinity on Arabidopsis Wild Type and Mutant Strands RDR6 and DCL4

3/23/2

009

3/25/2

009

3/27/2

009

3/29/2

009

3/31/2

009

4/2/2

009

4/4/2

009

4/6/2

009

4/8/2

009

4/10/2

009

4/12/2

009

4/14/2

0090

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Arabadopsis Leaf Width

WT Control

DCL4 Control

RDR6 Control

WT Treatment

DCL4 Treatment

RDR 6 Treatment

Leaf

Dia

met

er (c

m)

Results

The data that was collected showed several effects that the NaCl had on the Arabidopsis plants. It was observed that the tricomes on the plants leaves were textured differently than the control due to the amount of NaCl added to the solution. It can be assumed that the change was a sign of stress on the plant. It was also noticed that the RDR6 and control leaves that were affected by the salt grew faster than the plant with the DCL4 gene. In the case of DCL4 treatment pot 1, the third plant showed signs of discoloration. A sign of color change on a plant is a certain signal that the plant is undergoing some amount of stress. Almost all of the treated plants had different qualitative effects than the controls, such as longer, narrower leaves and more sizable tricomes. Conclusively, NaCL eminently affects the verdure and vitality of Arabidopsis plants.

Salinity’s Effect on Arabidopsis Wild Type and Mutant StandsRDR6 and DCL4

Salinity’s Effect on Arabidopsis Wild Type and Mutant StandsRDR6 and DCL4

Salinity’s Effect on Arabidopsis Wild Type and Mutant StandsRDR6 and DCL4