Studies On P. Tomentosa Genetic Diversity And Relationships With Relative Species In Prunus

Tomentosa cherry accessions were genetically analysed with both methods of morphology and SSR molecular markers.Relationships among P.Lithocerasus involving P.humilis,P. japonica,P.glandulosa and P.tomentosa all originated in China and with other species in Prunus were also analyzed.The main results are as follows:1.A collection of 44 Tomentosa cherry accessions from 10 eco-geographical regions was evaluated during two successive seasons on the basis of morphological descriptors. Morphological diversity was analyzed using a set of eighteen morphological traits.Significant differences between populations were noted for most morphological traits,highest variations being observed were fruit weight,fruit width and leaf width.The study revealed that the species is distributed in at least five northern China provinces and different accessions have their own specific morphological features.It was possible to identify several highly distinct accessions based on morphological characters.2.Genetic variation among Tomentosa cherries and 5 accessions from 3 relative species was characterized by SSR markers developed from peach,sweet cherry,sour cherry and apricot. 44 out of 110 SSR markers(40%)could be transferred to Tomentosa cherry and the other 3 species.A total of 250 alleles were detected with an average of 5.68 alleles per locus and an average polymorphism information content of 0.52.The results demonstrated the usefulness of cross-species transferability of microsatellite sequences allowing the discrimination of different genotypes of a fruit tree species with sequences developed in other species of the same genus.UPGMA analysis of the similarity data clustered the P.japonica,P.glandulosa and P.humulis into one group and the accessions of P.tomentosa into another parallel group with strong bootstrap support.Within P.tomentosa,the whipping accessions formed a subgroup and the rest formed several groups that reflect their geographical origins.3.Relationships were analysed among P.Lithocerasus including P.humilis,P.japonica,P. glandulosa and P.tomentosa originatd in China with other species from P.prunophora,P. amygdalus and P.cerassus,using 24 pair of SSR markers developed from peach,sweet cherry,sour cherry and apricot.UPGMA analysis clustered the accesions into 3 groups of P. prunophora,P.amygdalus and P.ccerassus.The results agreed with the past study on Prunus classification.However,4 species of P.Lithocerasus did not cluster into one group,P.humilis, P.japanica and P.glandulosa clustered with P.salicina forming one group and P.tomentosa clustered with P.triloba forming a parllel group which showed a closed relasionship with P.salicina.4.SSR technique was used to study the genetic diversity between 21 cherry cultivars from two species:sweet cherry and ground cherry.Eighteen pairs of primers cloned from cherry, peach and apricot amplified a total of 83 alleles among the 21 cherry cultivars,with a mean of 4.6.The polymorphic information content values(PIC)ranged from 0.38 to 0.80,with a mean of 0.64.Seven sweet cherry cultivars showed unique bands or banding patterns.A fingerprinting key of 18 sweet cherry cultivars was constructed by 4 pairs of primers: UDP98-414,UDP98-406,UDP96-001 and PMS40.UPGMA cluster analysis of genetic distance separated the 21 cultivars of sweet cherry and ground cherry into two groups.