| Potato(Solanum tuberosum L.) is the world’s most important non-cereal food crop, widely grown in more than 150 countries, consumed by one billion people in their daily life. The cultivated potato is a tetraploid species, due to the complexity of tetrasomic inheritance, the genetic analysis of potato is very difficult. Therefore the diploid population is mainly used for the research of potato inheritance.Potato are usually consumed fresh, meanwhile they are widely used for the processing industry. Tuber shape is a very important tuber trait of potato, not only for the fresh market but also for the processing industry. Due to the irregular tuber shape, the costs for the processing industry would be higher. Cultivars with round tubers are often used for crisps and cultivars with long shape are used for fries. However, the genetic analysis of potato tuber shape is very limited now.The goal of our research was to construct a genetic map in a diploid population and QTL mapping of potato tuber shape. With this, the genetic analysis of potato tuber shape would be further uncovered. And it would lay the foundation of molecular marker-assisted selection breeding. A diploid population of 343 genotypes has been constructed by our lab in the former research, the female parent is DM1-3( S.phureja), with long tuber shape, and the male parent is 40-3(S.chacoense), with round tuber shape, our work was carried out on these materials. The main research results are as follows:1. The two parents and 178 progenies were induced in vitro, and experiments were replicated twice at 2014 and 2015. Through observation of the tuber shape of two parents, the female parent DM1-3 was with “long” tubers and 40-3 was with “round” tubers. After the harvest, tuber shape was evaluated quantitatively by using length/width(LW). The correlation analysis of the two years’ data, the results showed that the correlation coefficient was 0.92, indicated the phenotype data of tuber shape was very consistent between years and potato tuber shape character was stable. The average LW value of the 178 genotypes was 2.79 and 2.85 at 2014 and 2015 respectively, which was smaller than the mid parent value, therefore round tuber shape was dominant to long tuber shape. The tuber shape distribution of 178 genotypes didn’t fit normal distribution by X2 goodness-of-fit test.2. For genetic map construction, 821 pairs of SSR primers were used to amplify the genomic DNA of two parents and partial progenies, the results showed that 116 SSR primers were polymorphic. 165 polymorphism markers were produced by 116 SSR primers. Among these markers, 158 markers came from male parent and 7 came from female parent. The genetic map of the male parent has been constructed, the map consisted of 157 markers, 12 chromosomes were covered, the total length of the map was 688.3 c M and the average distance was 4.38 c M.3. The results of the correlation analysis showed that 13 markers were significantly associated with tuber shape, and they were almost located on chromosome 2 and 4. Further, one QTL LW04 was mapped on chromosome 4 by Map QTL® 6 software with MQM model, which positively control round tuber shape. The QTL was mapped on same position between 2014 and 2015, which explained 6.1% and 6.3% of the variation for tuber shape, respectively. |
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