A Study On The Molecular Evolution Passway Of Four Ecotypes Of Reed Growing In The Hexi Corridor In Adaption Of Drought-prone And Saline Habitats

We did research in Phragmites communis Trin.-dune reed(DR), heavy-salt meadow reed(HSMR), swamp reed(SR), light-salt meadow reed(LSMR) growing in Hexi Corridor, Lin Ze county in Gansu province about their molecular evolutional passway in adaption to drought-prone and saline habitats. We detected the value ofδ¹³C and the contents of Na⁺ in the leaves of four ecotypes of reed. STR (short tandem repeats) and RAPD(random-amplified polymorphic DNA) markers were used to analyse the genetic diversity of different ecotypes of reed. The results are as follows:(1) There is remarkable differentiation of the value ofδ13C in four ecotypes of reed. The highest is DR(-25.933), there is gradually decrease in according to the sequence of LSMR(-26.186), SR(-26.405), HSMR(-26.632). The value ofδ¹³C in DR is most different from other ecotypes of reed. Water maybe the mostly factor in effecting the differentiation of DR.(2) HSMR has the highest contents of Na⁺,the contents of Na⁺ are 22.8667%; SR has the lowest contents of Na⁺,the contents of Na⁺ are 3.9125%. The contents of Na⁺ in HSMR is most different from other ecotypes of reed. Salinity maybe the mostly factor in effecting the differentiation of HSMR.(3) Seven primers were screened from 10 STR primers and got a total of 38 genetic locations, among which 34(89.5%) were polymorphic; The genetic distance of four different ecotypes of reed was between 0.06973 and 0.24613. Although there is faster evolution speed in chloroplast genome non-coding district, the STR analysis of reed in chloroplast genome non-coding district can not post the evolution relation of different ecotypes of reed growing in Hexi Corridor effected by many environmental factors.(4) Nine primers were screened from 20 arbitrary RAPD primers and got a total of 106 genetic locations, among which 106(100%) were polymorphic; The genetic distance of four different ecotypes of reed was between 0.05581 and 0.34226. The analytic results of RAPD are consistent with the compartmentalize standard about the shape and physiological characteristics of different ecotypes of reed growing in Hexi Corridor in our experiment. The analysis of variation of reed genome by RAPD can show the evolutional relation of different ecotypes of reed growing in Hexi Corridor.According to the analysis results of physiology and molecular markers we conclude that the evolutional direction of different ecotypes of reed growing in Hexi Corridor: from SR to LSMR to HSMR, forming DR at last. The analytic results of RAPD show that DR has the farthest genetic distance with three other ecotypes of reed, so water maybe the important environmental factor in influencing the evolution of different ecotypes of reed, salinity takes the second place.