Beyond the darkness: recent lessons from etiolation and de-etiolation studies

Abstract

The state of etiolation is generally defined by the presence of non-green plastids (etioplasts) in plant tissues that would normally contain chloroplasts. In the commonly used dark-grown seedling system, etiolation is coupled with a type of growth called skotomorphogenesis. Upon illumination, de-etiolation occurs, marked by the transition from etioplast to chloroplast, and, at the seedling level, a switch to photomorphogenic growth. Etiolation and de-etiolation systems are therefore important for understanding both the acquisition of photosynthetic capacity during chloroplast biogenesis and plant responses to light—the most relevant signal in the life and growth of the organism. In this review, we discuss recent discoveries (within the past 2–3 years) in the field of etiolation and de-etiolation, with a particular focus on post-transcriptional processes and ultrastructural changes. We further discuss ambiguities in definitions of the term ‘etiolation’, and benefits and biases of common etiolation/de-etiolation systems. Finally, we raise several open questions and future research possibilities.

Spatial Nano-Morphology of the Prolamellar Body in Etiolated Arabidopsis thaliana Plants With Disturbed Pigment and Polyprenol Composition

“…Although the skotomorphogenesis (etiolated growth) has been a subject of many studies and the use of the etioplast model to track the chloroplast biogenesis at different levels of their organization is quite common (reviewed in Adam et al, 2011 ; Gabruk and Mysliwa-Kurdziel, 2015 ; Pogson et al, 2015 ; Rast et al, 2015 ; Mechela et al, 2019 ; Armarego-Marriott et al, 2020 ), no uniform model of plant cultivation was established. In this study, we examined whether different, typically used, conditions of Arabidopsis etiolation could impact the PLB development, and therefore, be the source of literature discrepancies.…”

Dark-Induced Hormonal Regulation of Plant Growth and Development

“…Ample amount of information is available about how plants sense and respond to the complex light spectra, but the information is missing about their behavior under darkness, and light and dark signal interaction. Since, light simply reverses the dark-mediated development by activation of the photoreceptors, it has been speculated that the inactive photoreceptors might act as dark receptors and mediate the dark-triggered signal transduction ( Seluzicki et al, 2017 ; Gommers and Monte, 2018 ; Armarego-marriott and Sandoval-ibañez, 2020 ). Nonetheless, exact mechanism of dark sensing and perception is still unknown, and the idea of darkness perception by the inactive light receptors is a matter of debate.…”

Role of Phytohormones and Light in De-etiolation

“…Depending on the absence or availability of light, young seedlings pursue one of the two programs of development: etiolated growth (skotomorphogenesis) or de-etiolation (photomorphogenesis), respectively [1][2][3]. Etiolated dicotyledons produce an apical hook for protection of the apical meristem; they lack leaves and have proplastids and etioplasts instead of chloroplasts.…”

“…The French word étiolier stands for straw, which approximately corresponds to the color of etiolated plants. Some problems concerning photomorphogenesis have been discussed in a recent review by Armarego-Marrriott et al [3]. De-etiolation is morphophysiological process associated with suppression of shoot growth, apical hook opening, emergence of leaves, and formation of the photosynthetic apparatus.…”