Study On Dichondra Repens Germplasmin By RAPD And SRAP And Regional Adaptability Of Excellent Native Material

In this paper,the technique of RAPD and SRAP molecular markers were used to study genetic diversity of 20 native Dichondra repens and one conrol variety imported from America,for obtaining the complete information of genetic classification and relationship,then providing theoritical evidence for germplasm resources protection and utilization and variety breeding. In the study,an excellent materical of native Dichondra repens and one control variety:a reference species imported from America was selected for regional adaptability evaluation.The excellent native Dichondra repens has been optimized through comprehensive evaluating from 30 native Dichondra repens collected from Southwest of China. The major results as follows:1).Using the similar research methods of other plants,the RAPD and SRAP amplification programs were optimized to set up the reaction system of RAPD and SRAP fitting for analyzing the resources of Dichondra repens with the orthogonal diagram.2).The genetic diversity of 21 material were evaluated by RAPD marker,twenty primers were used and 189 bands were produced,of which 130 (68.78%) were polymorphic,the amplified band ranged from 6bands to 13bands, and each primer generated 6.5 polymorphic bands.The coefficient range of genetic similarity (GS) was 0.323-0.984 with 0.665 on average,which showed rich genetic diversity of Dichondra repens germplasm.21 matericals could be divided into 2 main groups by cluster.In most cases,materials from the similar geographical environment were classified into the same group,and the classification was related to the morphological characteristics and geographical distribution. In spite of the worse repeatability,the research suggested RAPD was a useful marker system for primary or ordinary genetic research.3).21 materials of Dichondra repens were analyzed by 19 highly polymorphicand stable primer pairs selected from 80 pairs of SRAP primer.The conclusions were showed: nineteen primer pairs produced 212 bands,including 156 polymorphic bands (8.2 polymorphic bands per primer pair).The average percentage of polymorphic bands was 73.58%.Genetic similarity of Dichondra repens was calculated by Nei method and the results were:the genetic similarity was ranging from 0.444-0.980 with 0.711 on average.These results suggest that there was a rich genetic diversity among the resources of Dichondra repens tested. The shape of the SRAP dendrogram reflected that 21 materials of Dichondra repens could be divided into three groups.Moreover,the materials from the same origin frequently clustered into the same group,and the classification was related to the morphological characteristics and geographical distribution too,which indicated the representativeness of all experiment germplasm and showed the genetic diversity and relationship of native Dichondra repens in southwest China.4) The correlation between RAPD and SRAP(r0.01=0.930) indicated that the two methods were rather highly consistant and the optimized systems were stable in detecting genetic diversity and genetic relationships in Dichondra repens, though some materials still clustered different between the two markers.5) The value of GS was estimated between 0.426-0.969 of 21materials based on the RAPD and SRAP analysis,and the average is 0.689,which is between RAPD and SRAP,but it is of no significant difference.The polygenetic tree of the genetic relationship in 21 individuals was drawn,and divided into two groups.It is closely similar with the RAPD and SRAP.Comparatively,it is more similar to the latter one.6).During the period of 2009 to 2010,the adaptability of an excellent native Dichondra repens material was evaluated comprehensively in four regions of southwest China.As it was showed:GD200503 has long green period, fast mature time, pretty good homogeneity, strong resistance with excellent turf-used characteristic.In the regions of Ya'an and Hongya, GD200503 can be keeping green above 320d, and except in Wenjiang,GD200503 has longer green period than CK in the other three regions.The range of mature time of GD200503 is from 55d to 60d,3d to 9d longer than CK.The leaf area ranges from 0.57 cm2 to 0.66cm2,0.38 cm2 to 0.96 cm2 smaller than CK. The leaf color of GD200503 is light green,and that of CK is deep green.The turf height of GD200503 is shorter than that of CK in four regions.Conprehensively analysising leaf area,leaf color, homogeneity, turf height, leaf gauffer, resistance.mature time and green period,GD200503 is an excellent native material with potential.In general,rich diversity can be observed in DNA formation.The genetic variance was correlated with geographic distribution and morphological characters.The genetic similarity between GD200503 and CK were 0.397(based on RAPD) and 0.527(based on SRAP),showing far genetic distance. In regional adaptability, differences also existed in morphology and fastness between these two materials.By those token, GD200503 was a excellent native materical with higher application potential,differing from control variety in genetic basis and morphology.