Arabidopsis thaliana

Arabidopsis thaliana
source
Name	Arabidopsis thaliana
Genus	Arabidopsis
Species	thaliana
Authority	(Carl Linnaeus) Heinh.
Synonyms	*Arabis thaliana L.

Arabidopsis thaliana. Commonly known as thale cress, it is a small flowering plant in the family Brassicaceae. Native to Eurasia and Africa, it has become a preeminent model organism in plant biology and genetics. Its small size, rapid life cycle, and fully sequenced genome have made it instrumental for fundamental research, analogous to the role of Drosophila melanogaster in animal studies.

Description and taxonomy

The plant typically forms a basal rosette of leaves from which grows a simple stem bearing small white flowers. It was first described by Carl Linnaeus and later reclassified into the genus *Arabidopsis* by Johann Gottfried Zinn. Its close relatives within the Brassicaceae include economically important crops like Brassica oleracea and Brassica rapa. The species exhibits considerable natural variation, with numerous ecotypes collected from diverse geographical locations, such as the widely used Landsberg erecta and Columbia strains. This variation is studied by institutions like the Arabidopsis Biological Resource Center.

History and model organism status

Its adoption as a model system was championed in the mid-20th century by researchers including Friedrich Laibach, who highlighted its potential. Systematic efforts to develop its genetic tools were later advanced by scientists such as George Redei and Maarten Koornneef. A pivotal moment was the launch of the multinational Arabidopsis Genome Initiative in the 1990s, which culminated in the complete sequencing of its genome by the year 2000, a project involving The Institute for Genomic Research and the Salk Institute. Its status was solidified by its use in pioneering studies of flowering time genetics by Detlef Weigel and plant hormone signaling.

Genome and genetics

It possesses a relatively small genome of approximately 135 megabase pairs distributed across five chromosomes. The sequencing effort, a landmark in biology, revealed over 27,000 genes and provided a blueprint for comparative genomics with crops like Oryza sativa. Key genetic tools developed for it include extensive T-DNA insertion mutant collections, such as those generated by the Salk Institute Genomic Analysis Laboratory. Research on its genome has elucidated fundamental mechanisms like RNA interference, studied by David Baulcombe, and epigenetic regulation, explored by Steve Jacobsen.

Growth and life cycle

Under optimal laboratory conditions, its life cycle from seed germination to mature seed production can be completed in about six weeks. Growth is highly responsive to environmental cues such as photoperiod, vernalization, and nutrient availability, processes studied by Joanne Chory and Mark Estelle. The plant's development follows a standard pattern, progressing through distinct phases: vegetative rosette growth, bolting of the inflorescence stem, and flowering. Its small stature and ability to grow at high density on agar plates make it ideal for large-scale genetic screens conducted at facilities like the European Arabidopsis Stock Centre.

Research applications

It serves as a foundational system for investigating nearly all aspects of plant biology. Major research areas include plant defense responses against pathogens like Pseudomonas syringae, abiotic stress tolerance to drought and salinity, and the biosynthesis of secondary metabolites. Discoveries in its circadian clock, by Andrew Millar, and light signaling pathways, involving phytochromes and cryptochromes, have had broad implications. Its genetic tractability also makes it a testbed for synthetic biology projects and for studying the effects of climate change, supported by resources from the National Science Foundation.

Category:Brassicaceae Category:Model organisms