Specialization of Oleosins in Oil Body Dynamics during Seed Development in Arabidopsis Seeds  

Abstract

Oil bodies (OBs) are seed-specific lipid storage organelles that allow the accumulation of neutral lipids that sustain plantlet development after the onset of germination. OBs are covered with specific proteins embedded in a single layer of phospholipids. Using fluorescent dyes and confocal microscopy, we monitored the dynamics of OBs in living Arabidopsis (Arabidopsis thaliana) embryos at different stages of development. Analyses were carried out with different genotypes: the wild type and three mutants affected in the accumulation of various oleosins (OLE1, OLE2, and OLE4), three major OB proteins. Image acquisition was followed by a detailed statistical analysis of OB size and distribution during seed development in the four dimensions (x, y, z, and t). Our results indicate that OB size increases sharply during seed maturation, in part by OB fusion, and then decreases until the end of the maturation process. In single, double, and triple mutant backgrounds, the size and spatial distribution of OBs are modified, affecting in turn the total lipid content, which suggests that the oleosins studied have specific functions in the dynamics of lipid accumulation.The seed is a complex, specific structure that allows a quiescent plant embryo to cope with unfavorable germinating conditions and also permits dissemination of the species. To achieve these functions, seeds accumulate reserve compounds that will ensure the survival of the embryo and fuel the growth of the plantlet upon germination. Accumulation of lipids occurs in many eukaryotic cells and is a rather common means of storing carbon and energy. Lipid droplets (LDs) can be found in all eukaryotes, such as yeast (Saccharomyces cerevisiae;

MYB118 Represses Endosperm Maturation in Seeds of Arabidopsis

“…Histochemical detection of GUS activity and bright-field microscope observations were performed as described by Baud et al (2007a). Observations of oil bodies in embryo and endosperm cells were performed as described by Miquel et al (2014).…”

Characterization of a new class of blue-fluorescent lipid droplet markers for live-cell imaging in plants

“…Further, the small number of LD dyes available for use in live plant cells, like BODIPY and Nile Red has certain drawbacks during multicolor imaging. While Nile Red has a very broad emission range interfering with the chlorophyll fluorescence and hindering multicolor imaging (Miquel et al, 2014), BODIPY 493/503 with its lesser photostability and photoconvertible properties limit its use for long term, repetitive imaging (Ohsaki et al, 2010). Despite the presence of other LD dyes with better photostability such as BODIPY 505/515 ,LD540 (Spandl et al 2009) or blue-red colored dual behaving monodanylpentane (Yang et al, 2012) the problem still remains that they have emission in the green, yellow or red region of the visible spectrum.…”

“…On the other hand, most of the commercially available live cell, LD dyes are limiting in their ability to penetrate plant cell wall and those that are permeable, such as Nile Red and BODIPY 493/503 have certain drawbacks. Not only does Nile Red have a broad emission range occupying the orange and red regions of the spectrum, but also its absorption significantly overlaps with widely used green and red reporters such as EGFP and mCherry, hindering the use of most ready-made fluorescent reporters in colocalization experiments (Miquel et al, 2014). Although BODIPY 493/503 (which fluoresces in green) can be combined with red-fluorescent constructs for two-color imaging, its lesser photostability and photoconvertible properties limit its ability to be utilized in long term imaging experiments (Ohsaki et al, 2010).…”

Development of novel dyes and fluorescence-imaging based approaches for cellular localization and dynamics of lipid droplets

“…Furthermore, the small number of LD dyes available for use in intact live plant cells, like BODIPY and Nile Red, have certain drawbacks, especially during multicolor imaging. Nile Red has a very broad emission range which interferes with the chlorophyll fluorescence, limiting its use in green plant tissues and also hinders multicolor imaging (Miquel et al, 2014). BODIPY 493/503 on the other hand, is known to have lesser photostability and undesirable photoconvertible properties, limiting its use for long-term, repetitive imaging (Ohsaki et al, 2010).…”

“…Such imaging tools in combination with photostable genetically encoded fluorescent proteins can be used in multiplexed tracking of protein remodeling on LDs (Tsien, 2009). Photo-switchable fluorescent proteins as well as fluorescent timers can be used for the quantitative assessment of LD protein dynamics (Terskikh et al, 2000;Chudakov et al, 2007 (Miquel et al, 2014). Although BODIPY 493/503 (which fluoresces in green) can be combined with red fluorescent constructs for two-color imaging, its lesser photostability and photoconvertible properties limit its ability to be utilized in long-term imaging experiments (Ohsaki et al, 2010).…”