Changes in the potato (Solanum tuberosum L.) tuber at the onset of dormancy and during storage at 23 degrees C and 3 degrees C. II. Evaluation of protein patterns

The changes in polypeptide profiles (2D-PAGE) occurring in the soluble and microsomal fractions of parenchymatic tissue of potato (Solanum tuberosum L.) tubers were studied during the last 30 d of maturation and during storage at 23 °C and 3 °C. The major changes were observed in the last period of tuber maturation, when several polypeptides disappeared and new ones appeared. At both 23 °C and 3 °C specific polypeptides disappeared in dormant tubers and new polypeptides appeared during storage. At 3 °C specific changes in protein composition occurred, particularly in the microsomal fraction. The changes in polypeptide profiles are discussed in relation to the transition from 'sink' to 'source' of the tuber, the onset of dormancy and of sprouting ability and the activation of cold acclimation responses. The results are also discussed on the basis of the physiological and biochemical changes that occur in the parenchymatic tissue.