Study on the hereditary variation of Jinzaoshi persimmon (Diospyros sp.) seedling progeny and the reproduction characteristics analyses based on SCoT and IRAP markers

Abstract: 【Objective】Jinzaoshi persimmon (Diospyros sp.) is one of the important economic fruit trees inZhejiang province. It is generally considered a new species of Diospyros. Its fruits can be seedless or seedbearing in different producing areas. However, its staminate flowers remain undetected and its reproduc-tion characteristics remain mistery. Some plants producing seeds stably were found in Qingyuan county of Zhejiang province. Seedling populations were used for studying the hereditary variations and reproductioncharacteristics by using SCoT and IRAP markers. The reproduction character of Jinzaoshi was also ana-lyzed based on the hereditary variation of these seedlings.【Methods】Two batches of seeds from two Jinza-oshi persimmon plants were collected in Qingyuan county, Zhejiang province in December of 2013. Then,the seeds were sowed in Persimmon Repository of Subtropical Forestry Research Institute, Chinese Acade-my of Forestry. In 2014, fifteen individuals from QY1(population 1) and 16 individuals from QY2(popula-tion 2) were randomly selected from the two seedling populations. Twelve individuals of Jinzaoshi persim-mon from other locations and each plant of three Diospyros species(D. kaki, D. lotus and D. japonica) were used as control. By using SCoT and IRAP markers, the hereditary variations of these individuals were evaluated. Multiplex ratio, polymorphic information content and marker index were calculated. The calculation of DICE similarity coefficient and clustering analysis were carried out by NTSYSpc version2.10 e software.【Results】In 36 selected SCoT primers and 26 IRAP primers, 21 SCoT primers and 20 IRAP primers performed well in the tested materials, respectively. The results abtained by these primers showed that the polymorphism level detected by IRAP markers was slightly higher than that by SCoT markers. A total of 473 clear and reproducible bands were obtained, of which 454 were polymorphic and the polymorphism frequencies were 93.56%(SCoT) and 97.50%(IRAP) respectively. In population 1, among the well-amplified primers, 14 SCoT primers and five IRAP primers could detect the variations among the seedling individuals. The DICE similarity coefficient variation ranges were 0.637-1.000(SCoT) and 0.927-1.000(IRAP), and the 15 individuals were divided into four and three genotypes by the two kinds of molecular markers. In population 2, two SCoT primers and four IRAP primers could detect the hereditary variations among the seedling individuals. The DICE similarity coefficient variation ranges were 0.987-1.000(SCoT) and 0.981-1.000(IRAP), respectively. And the 16 individuals were divided into nine and eight genotypes, respectively. It means that both the two kinds of molecular markers could be used for the hereditary variations detection of Jinzaoshi perssimon seedling populations. The DICE similarity coefficients of population 1 were lower than those of population 2, but the variations of population 1 mainly exhibited on some particular individuals while the genotypes of population 2 showed more diversity. However, the genetic variations of the two seedling populations were both lower than those of the population of Jinzaoshi perssimon individuals from other locations. In the clustering analysis, the clustering dendrogram obtained by IRAP was slightly more complex than that of SCoT, but the basic tendencies was the same. All Jinzaoshi perssimon individuals clustered together, while individuals of D. kaki, D. lotus and D. japonica were placed separately from the Jinzaoshi perssimon clade. In the Jinzaoshi perssimon clade, the 31 seedling individuals from Qingyuan consisted a main secondary clade. Some of the 12 individuals from other locations were placed within the secondary clade, and the others were placed separately from the secondary clade. However, the hereditary variations indicated that genetic segregation had occurred in Jinzaoshi perssimon progenies. Therefore, sexual hybridization seems to be involved in the seeds formation of Jinzaoshi perssimon. Although the staminate flowers of Jinzaoshi have not been discovered yet till now, from the seed production characteristics of Jinzaoshi perssimon in the ex situ repository which contains staminate flowers of other closely related species, and the sequence analysis of ITS regions in our previous studies. We assumed the pollen donor was unlikely to be the other closely related species.【Conclusion】The hereditary variations of 31 seedling progenies from two different Jinzaoshi female parents and 12 individuals from other distributing areas were detected by SCoT and IRAP markers. Genetic segregation had occurred in both progeny populations generated from two different Jinzaoshi perssimon female parents. The polymorphism level obtained by IRAP was slightly higher than that of SCoT. And the polymorphism level of population 1 was slightly higher than that of population 2. The hereditary variation found in the two progeny populations revealed that sexual hybridizaiton played an important role in the seed formation of Jinzaoshi perssimon. Some of the seedling individuals generated from the same female parent showed identical patterns, indicating that Jinzaoshi perssimon might have the possibility of facultative apomixis. More detailed experiment should be carried out in the future to verify this.