Biogenesis and functions of lipid droplets in plants

Abstract

Journal of Lipid Research Volume 53, 2012 215developing seeds and other plant tissues that contribute to the synthesis of TAGs, although the relative contributions of these alternative pathways to TAG accumulation may vary depending on the tissue and/or species ( 1 ).There also has been a growing appreciation in the past few years that the compartmentation of neutral lipids in LDs of plants extends well beyond their role as simply static depots for carbon storage in seeds and, consequently, there is renewed interest in the cellular ontogeny and dynamics of this organelle. For instance, LDs are observed in nearly all cell types in plants, and although the biogenesis of LDs in nonseed tissues is still poorly understood, we now know that they are involved in many unique processes, such as stress response, pathogen resistance, and hormone metabolism. Furthermore, there are highly specialized roles for LDs in anther development, wherein LDs contribute signifi cantly to the formation of the hydrophobic barrier of the pollen coat as tapetal tissues undergo programmed cell death. Interestingly, this process is somewhat similar to the specialized role that LDs play in the formation of the hydrophobic barrier that comprises the outer layer of mammalian skin.Overall, knowledge of LD function in both seed and nonseed tissues has been greatly enhanced by efforts to characterize the major proteins that specifi cally associate with these organelles, namely oleosins, caleosins, and sterol dehydrogenases (steroleosins) ( Fig. 1 ). Here, after a brief description of LD biogenesis in plant cells, we review the functional properties of these major LD-associated proteins and discuss how they compare with the properties of their known or potential counterparts in yeasts and mammals. We also describe the specialized role of LDs in pollen coat formation and how this process has some The seeds of plants store signifi cant amounts of neutral lipids, namely triacylglycerols (TAGs), in cytosolic lipid droplets (LDs), most of which are subsequently mobilized immediately after germination in order to fuel the growth and development of the seedling prior to photosynthetic establishment. In developing seeds, TAGs are assembled in the endoplasmic reticulum (ER) from acyl-CoAs and glycerol by the conserved "Kennedy" pathway that operates in all eukaryotes. Recently, however, additional acylCoA-independent reactions have been identifi ed in

Saturating Light Induces Sustained Accumulation of Oil in Plastidal Lipid Droplets in Chlamydomonas reinhardtii

“…LDs are specialized intracellular organelles made of a neutral lipid core surrounded by a membrane lipid coat in which proteins are embedded (Huang, 1996). LDs serve as a temporary storage site for neutral lipids and also participate in the active synthesis and metabolism of these non-membrane-forming lipids (Goodman, 2008;Farese and Walther, 2009;Chapman et al, 2012;Goold et al, 2015;Tsai et al, 2015). The current model of LD biogenesis suggests that these lipid-rich subcellular structures arise from membrane budding or blistering; thus, the lipid molecules present in the LD lipid coat suggest its origin of biogenesis.…”

Lipid droplet-associated proteins (LDAPs) are involved in the compartmentalization of lipophilic compounds in plant cells

“…4 It is now appreciated, however, that lipid droplets have numerous functions beyond lipid storage in seeds and that they are present in nearly all plant cell types, many of which do not accumulate appreciable amounts of lipid, such as the cells in leaves, stems, and roots. 5 There is also emerging evidence that lipid droplets are highly dynamic organelles involved in a variety of cellular processes and physiological responses, some of which appear to be conserved among eukaryotes. [6][7][8] Nevertheless, the precise functions of lipid droplets in non-seed cell types in plants are currently poorly understood.…”

Caracteres anatómicos y fitoquímicos del tallo y raíz de Mammillaria uncinata (Cactaceae)

“…Adicionalmente, en el parénqui- (Ho et al, 2014). Dichas reservas constituidas principalmente por triacilglicéridos (TAGs) y proteínas oleosinas pueden ser movilizadas durante periodos de metabolismo activo (Chen et al, 1999;van der Schoot et al, 2011;Chapman et al, 2012). La presencia de lípidos o compuestos lipofílicos, como estructuras subcelulares en el tallo de M. uncinata, además de formar parte de las reservas de carbono en el tallo, podría representar una barrera hidrofóbica para prevenir la pérdida de agua o formar parte de una cubierta protectora contra patógenos, ataques de herbívoros y otros factores ambientales, como mencionan Rodrigues et al (2011).…”