Genetic Diversity Of Aquilaria Sinensis (Lour.) Gilg

Aquilaria sinensis(Lour.) Gilg is an endangered and endemic plant in SE China. In present study,ISSR molecular markers were used to investigate genetic diversity of this plant,and some suggestions were proposed to protect and utilize this important economical plant.We established the reaction system and amplified procedure suitable for A. sinensis,that is 25μl amplification reactions system containing 1^*PCR buffer,2.0 mmol/L MgCl₂,100 ng template DNA,200μmol/L dNTPs,1.1 U Taq DNA polymerase,0.4μmol/L primer.The optimal amplified procedure was as follows: after a pre-denaturing of 5 min at 94℃,45 cycles were performed with denaturing of 45 s at 94℃,annealing of 45 s due to 1-2℃lower than denaturing temperature of different primer,extension of 75s at 72℃,a final extension step of 7 min at 72℃.Of 100 ISSR primers screened,16 primers were used for 8 populations of A. sinensis and 1 population of A.agallocha Roxb.A total of 168 bands were resulted,of which 156 were detected in A.sinensis and 143 in A.agallocha.The ISSR analyses revealed a high level of genetic diversity at the species level(PPF=84.62%;Na =1.8462,Ae=1.4378,Hpop=0.2643,I=0.4038);and a relatively low level at the population level(PPF=38.78%,Na=1.3878,Ae=1.2637,Hpop=0.1497,I= 0.2196).The genetic diversity of Maoming population(MM) is the highest in A. sinensis populations.We presumed that the reason of high level of genetic diversity at species level is:A.sinensis distributed extensively in the recent historical period, which is better for exchang of gene;while biological characteristics of this species and exogenous factors lead to the relatively low genetic diversity of population level.High level of genetic differentiation is found among populations of A.sinensis (G_ST=0.4425).The analyses of UPGMA and PCA revealed that 8 populations of A. sinensis were sorted into two Lineages.Lineageâ… includes 5 populations which are located in Guangdong(MM,GG and GZ),Fujian(FJ) and Hainan(HN);Lineageâ…¡comprises 3 populations which are in Guangxi(GX) and Yunnan(YX and YM). At species level,The gene flow(Nm=0.6633＜1) was very limited,which lead to high differentiation among populations.The limitation of gene flow mostly occurred among populations between two lineages,while extensive gene flow was found among populations within lineage(Nm＞1) in recent historical period.As several mountains,such as Yunkai Mountains,located between the distributions of two lineages,Geographical isolation may be the main reasons hinder the gene flow between two lineages.The results of ISSR analysis also indicated that distinct genetic differentiation was between A.sinensis and A.agallocha,which supported their specific status.In additional,according to distribution pattern of genetic diversity in A.sinensis, some strategies were proposed to protect this plant.