Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/100423
Title: Desiccation sensitivity and activities of free radical-scavenging enzymes in recalcitrant Theobroma cacao seeds
Authors: Li, C.
Sun, W.Q. 
Keywords: Ascorbate peroxidase
Carbohydrate
Desiccation tolerance
Lipid peroxidation
Recalcitrant seed
Superoxide dismutase
Theobroma cacao
Issue Date: Sep-1999
Source: Li, C.,Sun, W.Q. (1999-09). Desiccation sensitivity and activities of free radical-scavenging enzymes in recalcitrant Theobroma cacao seeds. Seed Science Research 9 (3) : 209-217. ScholarBank@NUS Repository.
Abstract: Mature and immature axes of Theobroma cacao (cocoa) seeds tolerated desiccation under a rapid-drying regime to critical water contents of 1.0 and 1.7 g g-1 dw, respectively. These critical water contents corresponded to water contents below which activities of free radical-scavenging enzymes (ascorbate peroxidase, peroxidase and superoxide dismutase) decreased rapidly during desiccation. The decline in axis viability below the critical water content was correlated with sharp increases in lipid peroxidation and cellular leakage. Cotyledon tissues were more desiccation-tolerant than axes, with a low critical water content of 0.24 g g-1 dw. Desiccation sensitivity in cotyledon tissues was also correlated with the decrease in superoxide dismutase activity and increased lipid peroxidation products. However, in the cotyledons, no ascorbate peroxidase activity was detected at any water content, and peroxidase activity was gradually reduced as desiccation proceeded. Cocoa embryonic axes contained large amounts of sucrose, raffinose and stachyose but only traces of reducing monosaccharides. Desiccation sensitivity of recalcitrant cocoa axes did not appear to be due to the lack of sugar-related protective mechanisms during desiccation, and it was more likely related to the decrease of enzymic protection against desiccation-induced oxidative stresses.
Source Title: Seed Science Research
URI: http://scholarbank.nus.edu.sg/handle/10635/100423
ISSN: 09602585
Appears in Collections:Staff Publications

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