Recent developments in the localization of oil body-associated signaling molecules during lipolysis in oilseeds

Bhatla, Satish C.; Vandana, S.; Kaushik, Vibha

doi:10.4161/psb.4.3.7799

Cited by 29 publications

(23 citation statements)

References 53 publications

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“…20 Significant transient biomolecular changes have been reported in the recent past on oil body membranes in the cells of seedling cotyledons of oilseeds, accompanying lipolysis. 31,32 All these earlier findings from the other workers and the present observations on the preferential accumulation of PAA-binding putative calcium channels on/around the oil bodies point towards the expression simply showed very faint green fluorescence upon excitation (Fig. 2I and L).…”

Section: Resultssupporting

confidence: 86%

“…EGTA, a calcium-chelating agent, is routinely used to establish the involvement of calcium ions in various physiological processes. [22][23][24][25][26][27][28][29][30][31][32][33][34][35] It forms stable, water-soluble complexes with calcium ions, thereby blocking their passage across plasma membrane into the cell. 24 Safadi et al 25 reported the presence of a calcium-dependent proteinase (CDP) activity in the roots of Arabidopsis, using in gel assays.…”

Section: Resultsmentioning

confidence: 99%

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Co-localization of putative calcium channels (phenylalkylamine-binding sites) on oil bodies in protoplasts from dark-grown sunflower seedling cotyledons

Vandana

Bhatla

2009

Plant Signaling & Behavior

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IntroductionOilseeds store oil in the form of triacylglycerols (TAGs) in the organelles known as oil bodies. TAGs are rapidly converted to soluble metabolites via specialized metabolic pathways upon initiation of seed germination. 1 The protein constituents of oil bodies belong to the three major groups, comprising of structural proteins (oleosins and caleosins), enzymes (steroleosins and lipases) and minor proteins, like aquaporins. 2 The sequence of events prior to TAG hydrolysis by lipases to produce free fatty acids and glycerol, involves degradation of oleosins by a 65 kDa thiol protease 3,4 and phospholipid degradation by phospholipases. 5 This renders TAG matrix susceptible to lipase action. Oleosins are known to provide stability to oil bodies while caleosins play an important role in the biogenesis and degradation of oil bodies. 6,7 Calcium binding capacity of caleosins has been demonstrated in Arabidopsis and Sesamum indicum. 8,9 Recently, calcium concentrations as low as 100 nM have been shown to strongly modify the shape and aggregation state of purified oil bodies, thereby establishing the role of caleosins not only as a target for calcium-binding in artificial and purified oil bodies, but also as an effecter of oil body stability. 2 During seed germination, caleosins are involved in the interaction of lipid bodies with vacuoles and, thus, they play a role in the mobilization of storage lipids. 10 Based on these findings and observations from the author's laboratory on calcium-dependent proteolysis, the possibility of cation channels on/around the oil body surface for facilitating calcium availability could not be ruled out.In plant cells, ion channels permeable to Ca 2+ are so far known to exist on the plasma membrane, endoplasmic reticulum, tonoplast, nuclear and plastid membranes. 11 Electrophysiological studies have elucidated that plants possess Ca 2+ channels with different types of gating mechanisms, namely ligand-, voltageand stretch-activated. 12 Ca 2+ channels in plant cells are similar to the L-type channels characterized in animal systems. 13

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Co-localization of putative calcium channels (phenylalkylamine-binding sites) on oil bodies in protoplasts from dark-grown sunflower seedling cotyledons

Vandana

Bhatla

2009

Plant Signaling & Behavior

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“…Lipid reserve mobilization accompanying extension growth of the seedlings is also likely to exhibit photomodulation. Within the cells of seedling cotyledons, a transient expression of various enzymes (such as proteases) has been reported on the oil body membrane leading to various signaling events and disruption of OB membrane to provide access to lipase action on TAG matrix (Sadeghipour and Bhatla 2002;Vandana and Bhatla 2006;Bhatla et al 2009). Additionally, oil body constituents are also likely to get modified through the action of enzymes like LOX.…”

Section: Discussionmentioning

confidence: 98%

Photomodulation of fatty acid composition and lipoxygenase activity in sunflower seedling cotyledons

Yadav

Bhatla

2015

Acta Physiol Plant

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The dynamics of fatty acid composition is an important metabolic index of seed germination and seedling development process. Present investigations indicate a preferential mobilization of fatty acids, particularly linoleic acid, out of the oil bodies in sunflower seedling cotyledons. A lack of selectivity in the utilization of saturated fatty acids during seed germination is also evident. Lipoxygenase (LOX) may play a role in the reconstitution of membrane lipid composition as cells expand during seed germination. LOX activity is absent in sunflower seeds and appears during germination. Photo modulation of LOX activity is evident by its enhanced expression in lightgrown seedling cotyledons. Since sunflower LOX activity is easily solubilized by mild detergent, such as 2 % Triton X-100, the association of LOX with the membrane does not seem to be very strong unlike other membrane proteins, such as oleosins, which can be extracted only by stringent procedures. Sunflower LOX has only one pH optimum with linoleic and linolenic acids as substrates, indicating the presence of single isoform in the total soluble protein (TSP) and oil body (OB) extracts. OB-associated LOX exhibits substrate-dependent variation in its pH optima. Specific activity of TSP and OB-associated LOX increases as seedling growth progresses. Sunflower TSP-LOX activity is inhibited by some hydrophobic thiols. TSP as well as OB-associated LOX activity in sunflower cotyledons is modulated by Ca 2? availability in a negative way. A critical role of LOX is, thus, evident during seed germination in sunflower.

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“…Nile red, a fluorescent probe for neutral lipids, serves as an ideal agent to monitor spatial and temporal changes in intracellular neutral lipid accumulation sites (Bhatla et al 2009;Greenspan et al 1985). Nile red fluorescing molecules accumulated as early as during late globular stage of embryo development in sunflower (Fig.…”

Section: Spatial Distribution Of Neutral Lipidsmentioning

confidence: 99%

Temporal and spatial analysis of lipid accumulation, oleosin expression and fatty acid partitioning during seed development in sunflower (Helianthus annuus L.)

2009

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Biochemical and fluorescence microscopic imaging approach has been adopted to investigate the accumulation of oil bodies at specific stages of seed development in Helianthus annuus L. cv. Morden. Seed filling in sunflower is marked with a rapid accumulation of proteins and lipids upto 30 DAA, after which protein accumulation declines whereas lipids continue to accumulate. Earliest signs of lipid accumulation are evident as early as during globular stage of embryo development. Spatially, a developing seed exhibits enhanced lipid deposition in peripheral cells. Oil body biogenesis is observed as early as 10 DAA, as is evident from the fluorescence microscopic detection of Nile red-positive entities in the protoplasts. To begin with, expression of one of the oleosin (the principal oil body membrane proteins) isoforms (16 kDa), is slower than the other two (17.5 and 20 kDa). Fatty acid composition of oil body lipids is quite similar to that of total seed lipids. An enhanced accumulation of linoleic acid is evident during later stages of seed filling. The proportion of major saturated fatty acids, palmitic (16:0) and stearic (18:0), however, do not alter much during the later phases of seed development. Present findings provide new information on oil body development, lipid accumulation and fatty acid composition, for a better understanding of the phasing of physiological and biochemical events associated with oilseed development.

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Recent developments in the localization of oil body-associated signaling molecules during lipolysis in oilseeds

Cited by 29 publications

References 53 publications

Co-localization of putative calcium channels (phenylalkylamine-binding sites) on oil bodies in protoplasts from dark-grown sunflower seedling cotyledons

Co-localization of putative calcium channels (phenylalkylamine-binding sites) on oil bodies in protoplasts from dark-grown sunflower seedling cotyledons

Photomodulation of fatty acid composition and lipoxygenase activity in sunflower seedling cotyledons

Temporal and spatial analysis of lipid accumulation, oleosin expression and fatty acid partitioning during seed development in sunflower (Helianthus annuus L.)

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