Genetic Diversity Of Germplasm Resources In Ornamental Crabapple

Genetic diversity of phenotypic, physiological and molecular characteristics of 70 different species or varieties of ornamental crabapple were studied. It will be benefit the conservation, classification, identification, genetic enhancement and effective utilization of the ornamental crabapple gemrplasm resources. The main results were as follows:1.Phenotypic diversity Phenotypic diversity were measured based on 22 quantitative characters and 13 qualitative traits, such as fruit, flower, leaf and branch. Results showed that all quantitative characters were significant differences among different species or varieties, and their CV were ranging from 5.69% to 70.30%. There was obvious and diverse variation among non-numerical traits. Principal component analysis indicated that flower size, fruit size and branch length were the main traits that resulted in phenotypic variations among different species or varieties of ornamental crabapple.2.Physiological diversity The flavor of the fruits was very acid and poor quality by analying fruit internal quality indexes which was significantly different. Significant differences between the content of chlorophyll were found. No significant differences in photosynthetic parameters were found. The correlation between content of chlorophyll and net photosynthetic was significant positive. So chlorophyll content can reflect plant photosynthetic capacity. The ornamental crabapples were stronger cold resistance by detecting the relative conductivity with logistic equation.3.DNA diversity Twenty SSR primers which could produce clear and polymorphic bands were selected from 67 primers to be used for the PCR amplification of genomic DNA. The average genetic diversity index of different species or varieties was 0.411 and expected heterozygosity was 0.821. Variations in average genetic diversity information content were 0.308. The varieties originated from the same ragion or with a common parent in parentage were likely to be classified into the same group with the cluster. Apple cultivars were clustered into one group. Genetic relationship between Malus halliana var. spontanea and some species from North America were relatively close. Cluster analysis based on genetic distance were similar to the result of phenotypic cluster analysis, but there was a little diffrence.