Editing Arabidopsis thaliana (section)

==Development==

===Flower development===
{{Further|ABC model of flower development}}
''A. thaliana'' has been extensively studied as a model for flower development. The developing flower has four basic organs - [[sepal]]s, [[petal]]s, [[stamen]]s, and [[Gynoecium|carpel]]s (which go on to form [[Gynoecium|pistil]]s). These organs are arranged in a series of whorls, four sepals on the outer whorl, followed by four petals inside this, six stamens, and a central carpel region. [[Homeotic]] mutations in ''A. thaliana'' result in the change of one organ to another—in the case of the ''agamous'' mutation, for example, stamens become petals and carpels are replaced with a new flower, resulting in a recursively repeated sepal-petal-petal pattern.
[[File:ABC flower development.svg|thumb|150px|The ABC model of flower development was developed through studying ''A. thaliana''.]]

Observations of homeotic mutations led to the formulation of the [[ABC model|ABC model of flower development]] by [[Enrico Coen|E. Coen]] and [[Elliot Meyerowitz|E. Meyerowitz]].<ref>{{cite journal |vauthors=Coen ES, Meyerowitz EM |title=The war of the whorls: genetic interactions controlling flower development |journal=Nature |volume=353 |issue=6339 |pages=31–7 |date=September 1991 |pmid=1715520 |doi=10.1038/353031a0 |bibcode=1991Natur.353...31C |s2cid=4276098}}</ref> According to this model, floral organ identity genes are divided into three classes - class A genes (which affect sepals and petals), class B genes (which affect petals and stamens), and class C genes (which affect stamens and carpels). These genes code for [[transcription factor]]s that combine to cause tissue specification in their respective regions during development. Although developed through study of ''A. thaliana'' flowers, this model is generally applicable to other flowering plants.

===Leaf development===
Studies of ''A. thaliana'' have provided considerable insights with regards to the genetics of leaf morphogenesis, particularly in [[Dicotyledon|dicotyledon-type]] plants.<ref>{{cite journal |vauthors=Tsukaya H |title=Leaf development |journal=The Arabidopsis Book |volume=11 |pages=e0163 |date=2013-06-07 |pmid=23864837 |pmc=3711357 |doi=10.1199/tab.0163}}</ref><ref>{{cite journal |vauthors=Turner S, Sieburth LE |title=Vascular patterning |journal=The Arabidopsis Book |volume=2 |pages=e0073 |date=2003-03-22 |pmid=22303224 |pmc=3243335 |doi=10.1199/tab.0073}}</ref> Much of the understanding has come from analyzing mutants in leaf development, some of which were identified in the 1960s, but were not analysed with genetic and molecular techniques until the mid-1990s. ''A. thaliana'' leaves are well suited to studies of leaf development because they are relatively simple and stable.

Using ''A. thaliana'', the genetics behind leaf shape development have become more clear and have been broken down into three stages: The initiation of the [[leaf primordium]], the establishment of [[dorsiventrality]], and the development of a marginal [[meristem]]. Leaf primordia are initiated by the suppression of the genes and proteins of class I ''[[Evolutionary history of plants|KNOX]]'' family (such as ''SHOOT APICAL MERISTEMLESS''). These class I KNOX proteins directly suppress [[gibberellin]] biosynthesis in the leaf primordium. Many genetic factors were found to be involved in the suppression of these class I ''KNOX'' genes in leaf primordia (such as ''ASYMMETRIC LEAVES1,'' ''BLADE-ON-PETIOLE1'', ''SAWTOOTH1'', etc.). Thus, with this suppression, the levels of gibberellin increase and leaf primordium initiate growth.

The establishment of leaf dorsiventrality is important since the [[Anatomical terms of location|dorsal]] (adaxial) surface of the leaf is different from the ventral (abaxial) surface.<ref>{{cite journal |vauthors=Efroni I, Eshed Y, Lifschitz E |title=Morphogenesis of simple and compound leaves: a critical review |journal=The Plant Cell |volume=22 |issue=4 |pages=1019–32 |date=April 2010 |pmid=20435903 |pmc=2879760 |doi=10.1105/tpc.109.073601}}</ref>

===Microscopy===
''A. thaliana'' is well suited for [[light microscopy]] analysis. Young [[seedlings]] on the whole, and their roots in particular, are relatively translucent. This, together with their small size, facilitates live cell imaging using both [[fluorescence microscopy|fluorescence]] and [[confocal laser scanning microscopy]].<ref>Moreno N, Bougourd S, Haseloff J and Fiejo JA. 2006. Chapter 44: Imaging Plant Cells. In: Pawley JB (Editor). Handbook of Biological Confocal Microscopy - 3rd edition. SpringerScience+Business Media, New York. p769-787</ref> By wet-mounting seedlings in water or in culture media, plants may be imaged uninvasively, obviating the need for [[Fixation (histology)|fixation]] and [[dissection|sectioning]] and allowing [[time-lapse]] measurements.<ref>{{cite journal |vauthors=Shaw SL |title=Imaging the live plant cell |journal=The Plant Journal |volume=45 |issue=4 |pages=573–98 |date=February 2006 |pmid=16441350 |doi=10.1111/j.1365-313X.2006.02653.x}}</ref> Fluorescent protein constructs can be introduced through [[Transformation (genetics)|transformation]]. The [[plant morphology|developmental]] stage of each cell can be inferred from its location in the plant or by using [[green fluorescent protein|fluorescent protein]] [[biomarker|markers]], allowing detailed [[developmental biology|developmental analysis]].