Biochemical and Cytochemical Transformations in Germinating Coconut (Cocos nucifera Linn.)
Biochemical and Cytochemical Transformations in Germinating Coconut (Cocos nucifera Linn.)
- Journal of the American Oil Chemistry Society, 72(11), p.1385-1391, 1995 .
The mechanism of mobilization and utilization of lipids by the developing seedling and the involvement of different tissues in this process was examined in germinating coconut. The endosperm (lipid reserve)and haustorium (spongy tissue developed during germination)were separated from germinating coconuts at intervals of two weeks up to week 22, and assayed for lipase, isocitrate lyase, malate synthase, and catalase, as well as for lipids and sugars. Except for lipase, activities of all the other enzymes were absent in the endosperm during the entire period of germination. However, these enzymes were found to be activated after the tenth week after germination and plateaued at week 16. Induction of these enzymes indicated the operation of the glyoxylate cycle in the haustorial tissue. Glyoxysomes also were observed in the haustorium. The haustorium was shown to absorb triacylglycerol and free fatty acids from endosperm for subsequent conversion to sugars in this tissue. Haustorium therefore is a biochemically active tissue and is the site of operation of the glyoxylate cycle in germinating coconut.
CATALASE
COCONUT
FREE FATTY ACIDS
GERMINATION
GLYOXYLATE CYCLE
GLYOXYSOMES
HAUSTORIUM
ISOCITRATE LYASE
LIPASE
MALATE SYNTHASE
SUGARS
TRIACYLGLYCEROLS
The mechanism of mobilization and utilization of lipids by the developing seedling and the involvement of different tissues in this process was examined in germinating coconut. The endosperm (lipid reserve)and haustorium (spongy tissue developed during germination)were separated from germinating coconuts at intervals of two weeks up to week 22, and assayed for lipase, isocitrate lyase, malate synthase, and catalase, as well as for lipids and sugars. Except for lipase, activities of all the other enzymes were absent in the endosperm during the entire period of germination. However, these enzymes were found to be activated after the tenth week after germination and plateaued at week 16. Induction of these enzymes indicated the operation of the glyoxylate cycle in the haustorial tissue. Glyoxysomes also were observed in the haustorium. The haustorium was shown to absorb triacylglycerol and free fatty acids from endosperm for subsequent conversion to sugars in this tissue. Haustorium therefore is a biochemically active tissue and is the site of operation of the glyoxylate cycle in germinating coconut.
CATALASE
COCONUT
FREE FATTY ACIDS
GERMINATION
GLYOXYLATE CYCLE
GLYOXYSOMES
HAUSTORIUM
ISOCITRATE LYASE
LIPASE
MALATE SYNTHASE
SUGARS
TRIACYLGLYCEROLS