This document provides an overview of Arabidopsis thaliana as a model organism for plant biology research. It notes that Arabidopsis is a small flowering weed with a short life cycle and small genome of approximately 135 million base pairs. The document discusses that Arabidopsis is easily transformed using Agrobacterium, has been widely used in epigenetics research due to DNA methylation and histone modifications, and is useful for studying a plant's response to its environment and stressors like light, nutrients, and pathogens.

1. ARABIDOPSIS - A Model
Organism

2. INDEX :
• INTRODUCTION
• GENOME LIFE CYCLE
• EASE OF TRANSFORMATION
EPIGENETICS
• RESPONSE TO ENVIRONMENT.

3. INTRODUCTION :
• Arabidopsis is a popular model organism used in
plant biology and genetics.
• It is a small flowering weed.
• Grows luxuriantly in temperate regions of the world.
• It is also known as thale cress, mouse-ear cress or
Arabidopsis.
• Named after 16th Century botanist JOHANNES THAL.
• Laibach - First to recognize the potential of Arabidopsis as a
model organism (in mid 90's).
• It is 20–25 cm tall.

4. THE GENOME LIFE CYCLE :
 It has a short life cycle.
 It has a small
genome.
 It has 5
chromosomes.
 The genome includes
105Mb of euchromatic
DNA,15 Mb of
seqeunced
heterochromatin, and
additional of 15-25 Mb
satellite repeats and
rDNA, thus a total of

5. EPIGENETICS :
 It is defined as mutation that is chromosomally inherited but
do not involve a change in nucleotide sequence.
 These mutation is associated with chemical modification of
DNA.
 Plants (Arabidopsis) is in epigenetic research for several
decades.
 Genomes are heavily modified by cytosine methylation
(RNA interference).
 When male and female germ lines differ imprinting results in
maternally inherited allele.
 It is prevalant in the extra embryonic endosper tissue.
 Epigenetics are often influenced by the environment. (Plants
remember cold of winter by flowering in the following spring).
 This process is regulated by RNA processing and histone

6. EASE OF TRANSFORMATION OF
EPIGENETICS :
 Agrobacterium tumefaciens induces tumorous growth due to
transfer of hormone biosynthesis gene from bacterial Ti
plasmid into chromosome of host plant.
 Ti genes are found in the T- DNA portion of the plasmid.
 Transformation in plants are done by replacing Ti gene with
gene of interest.
 Arabidopsis can be transformed either by spraying or dipping
them into concentrated culture of Agrobacterium in a
surfactant solution.
 Stable transformation occurs several days or weeks later
infection on the female gametophyte before fertiltzation.
 Transformed plants are selected by inducing selectable
marker gene (herbicides resistance) on media or soil
containing herbicides.
 Arabidopsis transformation efficiency is high.

7.  The insertions can be used for reverse genetics.
 By including transponsable elements in the T-DNA
transposon hops can be generated.
 Transposons have been the major tool for reverse
genetics in these plants than rice and maize.

8. RESPONSE TO ENVIRONMENT :
 The immune system of plants are widely diversified
and can recognize
viruses,microbes,worms,insects,etc.
 These are biotic stress caused to plants.
 In addition they also undergo abiotic stress such as
changes in light intensity, circadian
rhythm, nutrient, salt and water.
 These have various effects on the environment.
 Light plays central role in plant biology.
 Arabidopsis is replacing tobacco and spinach in
photosynthetic research.

9. RECENT RESEARCH :
 Functional Properties of a Cysteine Proteinase from
Pineapple Fruit with Improved Resistance to Fungal
Pathogens in Arabidopsis thaliana.

10. REFERENCE :
 Greilhuber, J., Borsch, T., Müller, K., Worberg, A., Porembski, S., and
Barthlott, W. (2006). Smallest angiosperm genomes found in
Lentibulariaceae, with chromosomes of bacterial size. Plant Biology, 8:
770-777.
 D.W. Meinke, J.M. Cherry, C. Dean, S.D. Rounsley, M. Koornneef
(1998). "Arabidopsis thaliana: A Model Plant for Genome
Analysis". Science 282 (5389): 662–682.
 Coelho SM, Peters AF, Charrier B, et al (2007). "Complex life cycles of
multicellular eukaryotes: new approaches based on the use of model
organisms". Gene 406 (1–2): 152–70.
 Clough SJ, Bent AF (1998). "Floral dip: a simplified method for
Agrobacterium-mediated transformation of Arabidopsis thaliana". Plant
J 16 (6): 735–743.
 Wang W, Zhang L, Guo N, Zhang X, Zhang C, Sun G, Xie J. Functional
Properties of a Cysteine Proteinase from Pineapple Fruit with Improved
Resistance to Fungal Pathogens in Arabidopsis thaliana. 2014 Feb
21;19(2):2374-89.