Changes in sugar content and activity of vacuolar acid invertase during low-temperature storage of potato tubers from six Japanese cultivars.
The storage of potato tubers at low temperatures leads to the accumulation of sugars in a process called "low-temperature sweetening." To understand this phenomenon, we measured the sugar contents and the activity of acid invertase over several months in tubers of six Japanese cultivars stored at 4 degrees C or 20 degrees C. At 20 degrees C, few changes in sugar contents took place in any of the tubers. On the other hand, when stored at 4 degrees C, three types of changes were observed among the cultivars: (1) increased levels of reducing sugars during storage; (2) a pattern similar to that of type 1, but with 4- to 6-fold lower levels of reducing sugars throughout storage; and (3) increased sucrose, but not reducing sugars. The activity of vacuolar acid invertase increased in the type-1 cultivars, whereas, in the type-2 and type-3 cultivars, the activities were very low during storage at 4 degrees C. Reverse transcription-polymerase chain reaction analysis of acid invertase showed that the transcripts of the enzyme accumulated in the tubers stored at 4 degrees C in the type-1 cultivars but not in type-3. These results suggest that the activity of vacuolar acid invertase is related to the types of changes that occurred in sugar content during low-temperature storage among the potato cultivars.
Department of Upland Agriculture, National Agricultural Research Center for Hokkaido Region, Memuro, Hokkaido 082-0071, Japan. mechie@affrc.go.jp
Chie
C
Matsuura-Endo
Akira
A
Kobayashi
Takahiro
T
Noda
Shigenobu
S
Takigawa
Hiroaki
H
Yamauchi
Motoyuki
M
Mori
D003080:Cold Temperature; D005511:Food Handling; D005519:Food Preservation; D005632:Fructose / Q000032:analysis*; D005947:Glucose / Q000032:analysis*; D011198:Solanum tuberosum / Q000737:chemistry* / Q000201:enzymology; D043324:beta-Fructofuranosidase / Q000378:metabolism*
D005632:Fructose; D043324:beta-Fructofuranosidase; D005947:Glucose