Construction Of A Diploid Potato Genetic Population And The Segregation In Cold Sweetening Resistance

The potato (Solarium tuberosum L.) is the fourth food crop with multiple uses in the world with their chips and fries are fashionable. In order to reduce the over much loss of moisture, development of sprout growth, cold storage of potato tubers at about 4℃is generally adopted to prolong the processing period. However, cold storage causes a large accumulation of reducing sugar (RS), as a consequence of the conversion of starch, that reacts with the amino acids under high temperature to result in undesirable dark brown color of the products. The starch-sugar conversion involves multiple metabolic pathways with many regulating factors. Therefore, mechanism of "cold-sweetening" (CS) is an important issue for improving potato post-harvest quality.In present study, a genetic segregation population was constructed through a cross of two diploid parents with distinct levels in the cold-sweetening and chipping qualities. Further molecular genetic markers analysis was performed. The main conclusions are as follows:1. Diploid wild spices S. berthaultii was used as maternal parent with CS-resistance and diploid succession line ED25 was used as paternal parent with CS-sensitivity. After crossing between them segregation population was obtained which contains 300 individuals and is denoted as "EB population".2. One hundred and ninety individuals including parents were grown in three geographic sites and RS of their tubers were tested after storage at 4℃for 60 days. A normal distribution was found in RS with a curve showing over-parent-extention, although the average RS obviously differed among the three sites.3. The recondition at 20℃for 21 days after the cold storage, the chip color index of selected 74 genotypes decreased by 13.7% from 8.019 to 6.920. Regression analysis indicated a significant correlation between the reducing sugar content of the tubers and their chip color index.4. Some genotypes exhibited good resistance to cold-sweetening, such as 064,179,166,109,035 et al; and some showed remarkable reduction in RS after recondition, such as 064,224,234,261,282,285,288,301 et al.5. One hundred and thirty-one pairs of SSR primers and 208 pairs of EST primers were used to test parents. The results showed that 111 pairs of SSR primers and 31 pairs of EST primers yielded distinct bands between parents; the polymorphic rate was 84.7% and 14.9%, respectively. Nineteen pairs of polymorphic SSR primers were used to test the EB population containing 183 individuals which showed 38 polymorphic bands,26 of them performed a segregation ratio of 1:1.