Arabidopsis thaliana (thale cress, mouse-ear cress)

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Taxonomic lineage

Arabidopsis thaliana belongs to family Brassicaceae (mustard or cabbage family). The family contains many economically important plants such as mustard (Brassica juncea, B. nigra and others), cabbage (Brassica oleracea), rape (Brassica napus) as well as many widely distributed weeds. The plants of this family are known as crucifers due to their uniform flower structure that resembles a cross. The crucifers are also characterized by a fruit named silique. The leaves are alternate (rarely opposite), sometimes organized in basal rosettes.

cellular organisms - Eukaryota - Viridiplantae - Streptophyta - Streptophytina - Embryophyta - Tracheophyta - Euphyllophyta - Spermatophyta - Magnoliophyta - eudicotyledons - core eudicotyledons - rosids - eurosids II - Brassicales - Brassicaceae - Arabidopsis - Arabidopsis thaliana

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Brief facts

• Arabidopsis thaliana (L.) Heyhn. (Brassicaceae) is a small, 10 - 40 cm tall, annual herb. The plant is a cosmopolitan generalist whose native range is considered to be Europe and the Middle Asian mountain system. The species is self-compatible and self-fertile. Arabidopsis thaliana can be found in a wide range of habitats in the Iberian Peninsula, including agricultural fields, banks and track sides, and openings of deciduous and Mediterranean forests and scrublands.
• The plant currently is widely distributed: over 750 natural accessions of Arabidopsis thaliana have been collected from around the world and are available from major seed stock centers.
• The Arabidopsis flowers from April to early June and disappears completely by late June.

The photographs show the habitat type and the area where permanent plots were laid down. Left and right panels are montane and coastal populations, respectively. Populations are ranked according to their altitude within each region. (Montesinos A et al. PLoS One. 2009 Sep 29⁵)

Value as a model organism

• Rapid life cycle (5-7 weeks).
• Each plant produces many seeds (up to 10,000 per plant).
• The plant has a small genome that has been completely sequenced.
• There are many available mutants.
• Can be easily transformed using Agrobacterium tumefaciens.

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Developmental stages (life cycle)

Life Cycle Stages

The plant completes its life cycle in about 50 days.

• seed stage MeSH
  • dormant seed
  • germination MeSH Emergence of radicle; 1-3 days after planting
• vegetative
  • seedling MeSH Three - ten days after planting
    ¹ 5-days old seedlings:
    
    • Development
      of true leaves. Seven - ten days after planting; the first true leaves can be distinguished by their color, shape and the presence of stellate trichomes
      ² 7- and 10-days old seedlings:
      
  • rosette stage Growth of rosette leaves (11-21 days after planting)
    ¹ 14- and 21-days old plants:
    
  • emergence of inflorescence
  • First flower buds
  • bolting Rapid growth of stem
• reproductive The plant produces reproductive organs - flowers
  ¹ 28-days old plants:
  
  • flowering
    • early flowering
    • full bloom Half of flowers are open
      ⁴ Position one represents anthesis and larger numbers are progressively older flowers:
      
    • late flowering New flowers are not produced; 40-43 days after planting
    • flowering complete
• seed development Embryogenesis and maturation (ripening); single plant usually has flowers as well as seed pods on different stages of development
  ⁴ Wild type silique and seeds:
  
• senescent Senescence begins around 45-50 day after planting

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Embryo development⁶

• Morphogenesis The process of the establishment of the embryo's body plan. Although the basic plant body is formed during embryogenesis, the vast majority of organ and tissue formation occurs post-embryonically
  • Double fertilization One sperm cell fuses with the egg cell to form zygote and another fuses with the central cell to form endosperm mother cell
  • Two-cell embryo The zygote divides asymmetrically to produce an apical cell that develops into an embryo proper and a basal cell that generates the hypophysis (gives rise to the root quiescent center and the initials of the central root cap) and the suspensor (transient structure)
  • Octant-stage
    proembryo Forms after longitudinal and transverse divisions
  • Dermatogen-stage
    embryo Forms after each cell of the previous stage undergoes a periclinal (parallel to the axis/surface) division generating the protoderm (embryonic epidermis)
  • Globular
    embryo Further embryonic development and patterning that results in the embryo of globular shape
  • Heart-shaped
    embryo Localized cell divisions lead to the emergence of cotyledon lobes and a shift in the morphological symmetry of the embryo from radial to bilateral
  • Tropedo stage
    embryo The embryo that has the basic elements of the plant body: the shoot apical meristem, cotyledons, hypocotyl, radicle and the root apical meristem; along the radial axis, the embryo consists of three primary tissues: the outer protoderm, the middle ground tissues and the inner procambium tissues
• Maturation Ripening; the process that involves cell expansion and accumulation of storage macromolecules to prepare for desiccation (metabolic quiescence), germination and early seedling growth

Tissues

Plant Components

• silique A fruit (seed pod) of 2 fused carpels that separate when ripe
• rosette A circular cluster of leaves that radiate from a center at or close to the ground; consists of approximately 20 leaves

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Flower anatomy

Kram BW, Xu WW, Carter CJ. Uncovering the Arabidopsis thaliana nectary transcriptome: investigation of differential gene expression in floral nectariferous tissues. BMC Plant Biol. 2009 Jul 15;9:92. PMID: 19604393

 

Schematic of Arabidopsis thaliana flower and nectarium. Arabidopsis flowers have four nectaries that comprise the 'nectarium'; two lateral nectaries (LN) occur at the base of short stamen, and two bilobed median nectaries (MN) occur in between the insertion points of two long stamen. (A) Schematic of Arabidopsis flower with front sepal and petals not shown. (B) Schematic cross-section of flower with relative location of floral organs from (A) indicated. A narrow ridge of tissue that occasionally connects median and lateral nectaries is indicated with dashed lines. Lateral nectaries produce >95% of total nectar in most Brassicaceae flowers, with median nectaries being relatively non-functional.

References

• Major topic "Arabidopsis": free full text articles in PubMed
• ¹ Krishnaswamy SS et al. Transcriptional profiling of pea ABR17 mediated changes in gene expression in Arabidopsis thaliana. BMC Plant Biol. 2008 Sep 10;8:91. PMID: 18783601
• ² Sangster TA et al. Phenotypic diversity and altered environmental plasticity in Arabidopsis thaliana with reduced Hsp90 levels. PLoS One. 2007 Jul 25;2(7):e648. PMID: 17653275
• ³ Deveaux Y et al. Genes of the most conserved WOX clade in plants affect root and flower development in Arabidopsis. BMC Evol Biol. 2008 Oct 24;8:291. PMID: 18950478
• ⁴ Kim J et al. Patterns of expansion and expression divergence in the plant polygalacturonase gene family. Genome Biol. 2006;7(9):R87. PMID: 17010199
• ⁵ Montesinos A, Tonsor SJ, Alonso-Blanco C, Picó FX. Demographic and genetic patterns of variation among populations of Arabidopsis thaliana from contrasting native environments. PLoS One. 2009 Sep 29;4(9):e7213. PMID: 19787050
• ⁶ Park S, Harada JJ. Arabidopsis embryogenesis. Methods Mol Biol. 2008;427:3-16. PMID: 18369993

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Appendix: experiments

Experiment 1

Krishnaswamy SS, Srivastava S, Mohammadi M, Rahman MH, Deyholos MK, Kav NN. Transcriptional profiling of pea ABR17 mediated changes in gene expression in Arabidopsis thaliana. BMC Plant Biol. 2008 Sep 10;8:91. PMID: 18783601

Appearance of WT and ABR17 transgenic A. thaliana in response to treatments. (A) Appearance of WT and transgenic ABR17 A. thaliana seedlings grown on MS media with 100 mM NaCl (B) Appearance of 7-day-old WT and ABR17 transgenic A. thaliana seedlings grown under dark.

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Experiment 2

Davis AM, Hall A, Millar AJ, Darrah C, Davis SJ. Protocol: Streamlined sub-protocols for floral-dip transformation and selection of transformants in Arabidopsis thaliana. Plant Methods. 2009 Feb 27;5:3. PMID: 1925052

Identification of doubly transformed A. thaliana lines generated using the 'double dip' protocol. A: Growth of A. thaliana seedlings on MS3 plates containing both gentamicin (100 μg/mL) and kanamycin (50 μg/mL). Seeds were harvested from a mother plant that had simultaneously been transformed with respective A. tumefaciens ABI lines separately harboring pPZP211-FRB/NLuc (gentamicin-resistance) and pPZP221-FRB/NLuc (kanamycin-resistance). B: Growth of a replicate batch of double-dipped A. thaliana seedlings on gentamicin alone. C: Growth of a replicate batch of double-dipped A. thaliana seedlings on kanamycin alone. Circles in A-C indicate antibiotic resistant plants. D: An expanded view of a robust seedling growing on both gentamicin and kanamycin. E: Multiplex genomic PCR of FRB and FKBP sequences in genomic DNA from nine lines selected on gentamicin alone. F: Multiplex genomic PCR of FRB and FKBP sequences in nine lines selected on both antibiotics. "FKB" indicates the PCR product obtained from a known kanamycin-resistant transgenic line; "FRB" indicates the PCR product obtained from a known gentamicin-resistant transgenic line; "WT" represents the negative control using a non-transgenic line.

Experiment 3

To JP, Reiter WD, Gibson SI. Mobilization of seed storage lipid by Arabidopsis seedlings is retarded in the presence of exogenous sugars. BMC Plant Biol. 2002 May 7;2:4. PMID: 11996676

Early exposure to high concentrations of exogenous glucose inhibits seedling development. Seedlings shown in the left column were grown on the indicated media for 10 days. Seedlings shown in the right column were grown on minimal media supplemented with 0.03 M glucose for 3 days, transferred to the indicated media and grown for an additional 7 days prior to photographing. Red bars = 2.0 mm. Glc, glucose; Sorb, sorbitol.

Seedlings sown directly on 0.27 M glucose exhibit little shoot development after 10 days of growth. In contrast, seedlings grown on 0.03 M glucose for 3 days and then for an additional 7 days on 0.27 M glucose produce very significant shoot systems. In fact, these plants have slightly larger average shoot systems than seedlings grown continuously on 0.03 M glucose. Interestingly, whereas seedlings sown directly on 0.24 M sorbitol + 0.03 M glucose produce larger shoot systems than seedlings sown directly on 0.27 M glucose, seedlings transferred to 0.24 M sorbitol + 0.03 M glucose after 3 days on 0.03 M glucose produce smaller shoot systems than seedlings transferred to 0.27 M glucose.

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