Low Temperature Sweetening in Potato Tubers: the Role of the Amyloplast Membrane
1995; Elsevier BV; Volume: 145; Issue: 3 Linguagem: Inglês
10.1016/s0176-1617(11)81899-7
ISSN1618-1328
AutoresEileen P. O’Donoghue, Rickey Y. Yada, Alejandro G. Marangoni,
Tópico(s)Polyamine Metabolism and Applications
ResumoProperties of the amyloplast membrane were examined for potato cultivars susceptible (Norchip) and resistant (ND860-2) to low temperature sweetening following storage for 4 months at either 12 °C or 4 °C. Chips from Norchip stored at 4 °C were darker and the tissue contained higher levels of glucose, fructose and sucrose as compared to ND860-2 tubers stored at 12 °C and 4 °C and Norchip tubers at 12 °C. Membrane lipid phase transitions of intact amyloplasts assessed using differential scanning calorimetry were higher for Norchip than ND860-2 tubers after storage at both 12 °C and 4 °C (45 vs. 38 °C and 35 vs. 27 °C,respectively). Fluorescence depolarization measurements using the probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and {ittrans}-parinaric acid (t-PA) indicated that the structural order parameters of Norchip amyloplasts membranes at 4 °C were higher than at 12 °C (0.655 vs. 0.459 with DPH and 0.658 vs. 0.531 with t-PA) while the opposite was true for ND860-2 (0.402 vs. 0.549 with DPH and 0.481 vs. 0.566 with t-PA). Small differences patterns of amyloplasts were observed between Norchip and ND860-2. Degradation of amyloplast unsaturated fatty acids was greater for Norchip membranes (93& decrease in double bond index) than for ND860-2 (70& decrease in DBI). The above results suggested that amyloplast membranes from Norchip potatoes senesced to a greater extent than ND860-2 amyloplast membranes upon exposure to low temperature and that this event may be associated with low-temperature sweetening.
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