From leaf to flower: revisiting Goethe's concepts on the ¨metamorphosis¨ of plants

Abstract

Goethe’s seminal scientific work, Versuch die Metamorphose der Pflanzen zu erklaren (An Attempt to Interpret the Metamorphosis of Plants) dated from 1790, has created the foundations for many domains of modern plant biology. The archetypal leaf concept, which considers floral organs as modified leaves, besides being the best known has been proven true, following the description of the ABC molecular model of floral organ identity determination during the last decade. Here we analyze the whole theoretical frame of Goethe’s 1790 publication and present two previously misconsidered aspects of this work: The "refinement of the sap" concept as a directional principle and the "cycles of contractions and expansions" as cycles of differential determination of the shoot apical meristem. The reinterpretation of these concepts are in line with the modern view that molecular networks integrate both environmental and endogenous cues and regulate plant development. This reassessment also helps to elaborate a theoretical frame that considers the evolutionary conservation of the molecular mechanisms that regulate plant development.

Regulation of Axillary Meristem Initiation by Transcription Factors and Plant Hormones

“…Von Goethe proposed that a flower can be considered a compressed shoot ( Dornelas and Dornelas, 2005 ). However, a flower differs from a shoot in its determinate growth, which results from transient AM activity and produces a limited number of floral organs.…”

Manipulation of VviAGL11 expression changes the seed content in grapevine (Vitis vinifera L.)

“…VviAGL11, as a MADS-box protein class D, is able to form the socalled floral quartets protein complexes. In this case, MADS-box proteins will bind other proteins from the same family but different classes (A, B, C and E), which afterwards can bind to two cis-elements called CArG-boxes and activate gene transcription [50,51]. The formation of transcription factor dimers and multimeric complexes offers a mechanism to increase the diversity of possible DNA-binding proteins enormously [52].…”

Charles Darwin and the Origins of Plant Evolutionary Developmental Biology

“…From first to last, the plant is nothing but leaf." These words (written in 1787, but not published until many years later by Goethe (1817) and translated into English by Mueller (Goethe, 1952), launched the modern age of comparative biology and were the basis of a formalized discipline, plant morphology (Engard, 1989;Coen, 2001;Kaplan, 2001;Dornelas and Dornelas, 2005;Friedman, 2009), developed by Goethe and published in 1790 in Versuch die Metamorphose der Pflanzen zu erkla¨ren (An Attempt to Explain the Metamorphosis of Plants). It is here that Goethe argues that all of the diverse lateral determinate organs of the shoot system are transformed (metamorphosed) manifestations of a true leaf.…”