Study On The Genetic Diversity Of Three Caragana Fabr. Species

C. korshinskii Kom. /C. intermedia Kuang et H.C.Fu. / C. microphylla Lam.are plants of Caragana Lam. in Leguminosae,which are mainly distributed in arid and semiarid areas of northwestern/northeastern china.They are not only high drought-tolerant and cold-resistant plants,but nourishing plants. They have high ecological and economical value. They play important roles in ecological environment construction,sand-control,dune-fixation and development of stock raising of Northwest part of China.In order to provide new evidence for the study of genetic diversity and relation among C. korshinskii Kom./ C. intermedia Kuang et H.C.Fu. and C. microphylla Lam.,34 meterials were investigated with the technique of ISSR analysis and morphological diversity,which were including 17 materials of C. korshinskii Kom., 12 materials of C. intermedia Kuang et H.C.Fu. and 5 materials of C. microphylla Lam. from Mongolia,Shanxi, Shaanxi and Ningxia. Main results are as follows:(1) Longitude and altitude have significant influence on the morphological variation.The morphological variation results from genetic factors and natural selection.(2) Morphological diversity is high in the C. microphylla Lam., C. korshinskii Kom.. and C.intermedia Kuang et H.C.Fu.. Pod length, Pod width, Seed length, Seed width and 1000-seed mass are main factors that result in morphological variation among the three species.(3) An optimized PCR reaction system for ISSR analysis was established:PCR was performed in a 10 μL reaction mixture with 40 ng DNA, 2.0mmol/L MgCL₂, 150 umol/L of each dNTP, 200nmol/L primer,0.5U Taq polymerase.The temperature profile used for PCR was 94℃ for 5 min, followed by 40 cycles of 94 ℃ for 45sec,52℃ for 45sec,72℃ for 90 sec, and was terminated with a 7min DNA extention step at 72℃. Then the production of PCR could be placed in refrigeratory at 4℃ for less than 24h.(4) In this experimentation, 154 bands were amplified with 19 ISSR primers among which 177(87.0%) was polymorphic respectively. The genetic diversity is high among the three species.(5) Although there is a slight difference in three species ,of which C. korshinskii Kom.,C. intermedia Kuang et H.C.Fu. and C. microphylla Lam. are closed in genetic relationship,but it cann't attribute them to one species with the results of morphological diversity and ISSR analysis. It needs more study on the classification relationship of the three species.