Pentose Phosphate Metabolism of Potato Tuber Discs as Influenced by Prior Storage Temperature

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Abstract
Tubers of Solanum tuberosum L. var. Russet Burbank, Kennebec, and Targhee were stored at 95% relative humidity and at 1.7, 4.4, 5.8, 7.2 or 10 C. Rates of O2 consumption were measured periodically by removing individual tubers from storage, excising discs of pith parenchyma tissue, and incubating the discs in a Gilson respirometer at 30 C. With all three varieties, data suggest a greater involvement of pentose phosphate metabolism with tissues from tubers stored at 1.7 C as compared to those from higher temperatures. Discs from tubers stored at 1.7 C had higher respiratory quotient values (CO2/O2), were substantially less sensitive to the inhibitory effects of iodoacetic acid, and were somewhat more sensitive to the inhibitory effects of salicylhydroxamic acid than the discs from tubers stored at higher temperatures. Using [14C]glucose labeled in the 1 or the 6 carbon, mean C1 to C6 ratios in the Gilson after 3.5 hours of aging were 4.8:1 with discs from tubers stored at 1.7 C and 2.5:1 with discs from tubers stored at 7.2 C. Prior storage history is important in metabolic studies using potato tubers.