Research On Breeding New Strains Of Potato Hybrids With High Quality And Yield And Black Scurf Resistance

To select new varieties of potatoes, which have the characters of high Rhizoctonia canker resistance, high quality and high-yield and have suitable growing period for area of Inner Mongolia, basing on the principle of ecotypes-diverse, traits complementarity between parents, we have selected potato cultivar Favorita as female parent, which is characterized by high quality, percocity, high-yield, high commodity rate, and selected J07-6 introduced from Japan, Longshu No.3 bred from China as male parents, which were both characterized by high resistance of Rhizoctonia canker, wide applicability, high contain of Vc and starch, Two hybrid F1 combinations have been produced successfully by artificial emasculation and crossing. Determine the main agronomic characters of superior single plant of clone 1 population to make initial selection, and identify authentic hybrids of superior single plants using SSR molecular markers. Evaluate and determine the traits of growth vigor, yield, quality of clone 2 population, and analyze the characteristic of cytogenetics to select main 4 superior lines: line A1, line A3, line A16 and line C2 of clone 3 population, thus, identify their resistance of Rhizoctonia canker in clone 4 population, and conduct further study of stability of the traits, such as growth vigor, yield and quality, and analyze the characters of SSR fingerprints. The main results are as follows:1. The study has selected 2 appropriate primer pairs S7 and STM1049 among the total 43 primer pairs to identify authentic hybrids of superior individuals of the F1 combinations Favorita×Longshu No.3 and Favorita×J07-6. At DNA level, 4 types of SSR bands were distinguished as heterozygous type, deletion type, Male parent type, female parent type. Those 34 and 27 individuals of F1 hybrids were identified as true hybrids from combinations Favorita×Longshu No.3 and Favorita×J07-6, respectively.2. The results of correlation analyses showed that: There is a positive correlation between yield per plant and plant height, stem diameter, main stalk number, tuber number per plant, average tuber weight, commodity potato rate, while number of plant branch shows the negative correlation. Taller plants which have appropriate main stalk and plant branch number should be chosen when breeding superior hybrid lines.3. Four superior potato lines, hybrid line A1, A3, A16 from Favorita×Longshu No.3, hybrid line C2 from Favorita×J07-6, are selected from clone 2 population of two combination, respectively, with traits of growth vigor, yield, quality performing well.4. There are pollen fertility variability in hybrid line A1, A3, A16 and C2, ranging between 11.99% ~ 76.19%. The hybrid line C2 has the highest amount of pollen fertility, while hybrid line A16 has the lowest.5. The karyotype of four tetraploid potato hybrid lines A1, A3, A16, C2, are 2B, 1B, 2A, 1A type, respectively. The karyotype formula of hybrid lines A1, A3 are both 2n=4x =48=48m, and hybrid line A16 is 2n=4x =48=44m+4sm, and hybrid line C2 is 2n=4x=48=48m.6. At PMC MⅠperiod,the univalent frequency of hybrid lines A1, A3, A16 and C2 rangs between 4.06%~53.35%, the bivalent frequency ranges between 3.45%~50.08%, the trivalent frequency ranges between 3.05%~42.70%, the quadrivalent frequency ranges between 4.32%~42.81%. Chromosome pairing configuration of hybrid line A1 is 13.29Ⅰ+1.24Ⅱ+9.31Ⅲ+1.08Ⅳ, line A3 is 10.44Ⅰ+1.33Ⅱ+9.80Ⅲ+1.38Ⅳ, line A16 is 12.99Ⅰ+0.85Ⅱ+9.56Ⅲ+1.16Ⅳ, line C2 is 0.68Ⅰ+8.45Ⅱ+0.51Ⅲ+7.22Ⅳ. That shows line A3, A16, C2 has maternal biased chromosome, while hybrid line A1 has paternal biased chromosome.7. Potato yields of cloning 4 population are stable. Their production HP was 45.56%, 31.75%, 34.92% and 50.95%, respectively. The amount of dry matter quantity ranges between 20.81%~27.53%, and starch ranges between 16.72%~22.68%, showing the highest proportion in superior line A3, and reducing sugar ranges between 0.01%~0.08%, showing lower proportion in all, and Vc ranges between 23.41~32.42mg/100 g, reaching the highest level in superior line A3.8. To infect potato tuber chips by inoculating Black Scurf germs, and strong resistance was found of hybrid line A1, hybrid line A3, hybrid line C2, while hybrid line A16 found the weakest.9. Genome DNA of 3 superior lines, lines A1, A3, C2 and their parents were amplified with 10 pairs of SSR primers. Total 50 SSR polymorphic bands were detected, and polymorphic bands rate was 79.37%. One SSR fingerprint map including 3 superior lines was established in the study.10. The genetic distance range(GD)of 3 superior hybrid lines is from 0.2903 to 0.7647, with a mean of 0.5342. Using the GD value 0.45 as threshold point, 6 potato materials could be clustered into 3 groups: The first group includes Favorita, hybrid line A1 and Longshu NO.3. The second group includes hybrid line A3, and C2 and J07-6 was clustered into one group separately.