Study On Diversity Of Phenotypic Characters And The Construct In Basic Database Of Malus Sieversii(Ledeb.) Roem

Malus sieversii(Ledeb.) Roem. is a remnant of the tertiary species, belongings to the national second-grade protected endangered species. Based on previous studies, the diversity of Malus sieversii was investigated by measuring several phenotypic characters, and then, germplasm resources database of Malus sieversii was established. The main results are shown as following:(1) In descriptive characters aspect, the average genetic diversity index was 0.895, the characters in the shape of fruit, tree vigor and posture, color of annual branches, rust rate of stalk cavity and quality of pulp had high genetic diversity index, while the index leaf color and rust rate of calyx were low, however, there were significant differences between populations in leaf color, fruit flavor and rust rate of calyx, which might be related to the difference in geographical distribution and phylogeny of populations. In numerical characters aspect, the variation coefficient of each character was up to 10%, furthermore, the variation coefficient of flavonoid was the highest one, more than 40%, and the variation coefficient of titratable acid, single berry weight and length of fruit stalk was up to 25%, while roughness of annual branches, transverse length of fruit and shape index of fruit were very low. These results indicated that diversity of phenotypic characters was abundant in the two Malus sieversii populations, in addition, variation was mainly within population, while there was no significant difference among populations, the diversity of fruit characters were more prominent.(2) Principal component analysis of fruit characters showed that the first 4 principal factors hold the vast majority diversity information, and the cumulative contribution rate was up to 76.89%. Among them, the fruit size factor was up to 32.72%, which suggested that the genetic diversity of fruit size were more prominent, fruit diameter had the significant effect on single berry weight. The eigenvalue vector of soluble solids, soluble sugar and titratable acid in the second factor was 0.64, 0.60 and-0.50, which showed that titratable acid is a limiting factor on content of soluble sugar in a certain extent, soluble solids had the significant effect on soluble sugar. The eigenvalue vector of fruit shape, vertical length of fruit and transverse length of fruit in the third factor was 0.66, 047 and 0.43, which showed closely relationship among them. The eigenvalue vector of soluble sugar in the forth factor was-0.47, which indicated that individual with higher flavonoid content had lower soluble sugar content in a certain extent.(3) 7 main kinds of flavonoids in the pulp of Malus sieversii were detected, and procyanidin B2, procyanidin C1, chlorogenic acid and epicatechin were widely distributed, the diversity had significant difference among populations.(4) The germplasm resources database of Malus sieversii containing the 56 phenotypic characters and pictures of 171 individuals was established with the function of adding, deletion, search and export based on Microsoft Access 2007 and Visual Basic 6.0.