LOW-TEMPERATURE STRESS INDUCES TRANSIENT OSCILLATIONS IN SUCROSE METABOLISM IN SOLANUM-TUBEROSUM

Exposure to low but nonfreezing temperatures induces the net breakdown of starch and the accumulation of sucrose, glucose and fructose in po tato tuber tissue, a complex phenomenon known as low-temperature sweet ening (LTS). When transferred to 4 degrees C storage, tissue sucrose l evels in LTS-sensitive potato tubers (Solanum tuberosum cv. Norchip) d id not change monotonically to a new steady state, but rather transien tly oscillated about the trajectory to the new steady state. The dynam ic patterns observed in sensitive tubers grown in 1993 and 1994 were q ualitatively similar. Quantitatively, however, the transient oscillati on had a period of 11.5 days in 1993, whereas a period of 80 days was observed in 1994. In contrast, the sucrose levels of the LTS-tolerant potato tubers (solanum tuberosum seedling ND860-2) increased monotonic ally to a higher level upon exposure to low temperatures.