RESUMO
Genetic diversity of Elymus sibiricus (Poaceae) was examined in eight populations from the southeast Qinghai-Tibet Plateau. We detected 291 RAPD polymorphic loci in 93 samples. The percentage of polymorphic bands (PPB) was 79%. Genetic diversity (H(E)) was 0.264, effective number of alleles (N(E)) was 1.444, Shannon's information index (H(O)) was 0.398, and expected Bayesian heterozygosity (H(B)) was 0.371. At the population level, PPB = 51%, N(E) = 1.306, H(E) = 0.176, I = 0.263, and H(B) = 0.247. A high level of genetic differentiation was detected based on Nei's genetic diversity analysis (G(ST) = 32.0%), Shannon's index analysis (33.7%), and the Bayesian method (θ(B) = 33.5%). The partitioning of molecular variance by AMOVA demonstrated significant genetic differentiation within populations (60%) and among populations (40%). The average number of individuals exchanged between populations per generation (N(m)) was 1.06. The populations were found to share high levels of genetic identity. No significant correlation was found between geographic distance and pairwise genetic distance (r = 0.7539, P = 0.9996). Correlation analysis revealed a significant correlation (r = 0.762) between RAPD H(E) found in this study and ISSR H(E) values from a previous study.
Assuntos
Elymus/genética , Variação Genética , Técnica de Amplificação ao Acaso de DNA Polimórfico/métodos , Altitude , Marcadores Genéticos , Genética Populacional , Geografia , Filogenia , Polimorfismo Genético , Estatísticas não Paramétricas , TibetRESUMO
Saccharum spontaneum is a wild sugarcane species that is native to and widely distributed in China. It has been extensively used in sugarcane breeding programs, and is being tested for the development of bioenergy cultivars. In order to provide basic information for the exploitation of this species, we analyzed genetic variation among and within native S. spontaneum populations collected from Sichuan, China. Eighty plants from nine native populations were sampled. Twenty-one sequence-related amplified polymorphism primer pairs generated 235 clearly scorable bands, of which 185 were polymorphic (78.7%). Nei's genetic diversity was 0.2801 and Shannon's information index was 0.4155 across the populations. Genetic diversity parameters, G(ST) value (0.2088) and N(m) value (1.8944), showed that the genetic variation within populations was greater than that among populations. In the cluster analysis, one major grouping was formed by populations from Ya'an and another one by populations from Sichuan basin; a population from Baoxing formed a single cluster. In order to fully comprehend the genetic diversity of cold-tolerant local germplasm in this species, germplasm should be collected from the heterogeneous environments along the northern regions of this species' distribution. The germplasm that we collected should be a valuable resource for Saccharum breeding.
Assuntos
Variação Genética , Saccharum/genética , Sequência de Bases , China , Primers do DNA , Reação em Cadeia da PolimeraseRESUMO
The sea cucumber (Apostichopus japonicus) is an important item in Asian cuisine. It is currently produced through aquaculture, especially in China, after being overexploited in the wild in the 1990s. We isolated 70 novel polymorphic microsatellite loci using an enrichment-colony hybridization protocol. All loci were characterized in 48 individuals from a natural population in Rongcheng (Shandong, China) using genomic DNA isolated from muscle tissue. The number of alleles ranged from 2 to 17 (mean 7.0), and the observed and expected heterozygosities varied from 0.0010 to 1.0000 and from 0.2125 to 0.9477, respectively. Thirty-one of the 70 loci exhibited departure from Hardy-Weinberg equilibrium. These microsatellite markers should be useful resources for population genetic studies and for molecular marker-assisted breeding of A. japonicus.