Development and characterization of novel microsatellite markers for Ginkgo biloba using 454 pyrosequencing.

As a "living fossil" that is used to understand the evolutionary history of seed plants, Ginkgo biloba is a well-known multipurpose tree with edible seeds, medicinal properties, and ornamental value, but little is known about its genetic diversity. Microsatellite, or simple sequence repeat (SSR), markers have proven to be powerful tools for genetic studies of plants. In this study, we isolated 30 novel polymorphic microsatellite loci in G. biloba using 454 pyrosequencing. The characteristics of these loci were tested with 48 cultivars. The number of alleles (NA) per locus ranged from two to seven. The observed (HO) and expected (HE) heterozygosities ranged from 0.000 to 0.750 and from 0.021 to 0.792, with an average of 0.326 and 0.443, respectively. In terms of genetic diversity in the Ginkgo population, NA was 3.300, NE was 2.090, I was 0.782, HO was 0.326, and HE was 0.443. These polymorphic SSRs will be useful for the assessment of population genetic diversity and resource conservation of G. biloba.

Associations between HLA-A\B\DRB1 polymorphisms and risks of vulvar lichen sclerosus or squamous cell hyperplasia of the vulva.

In this study, we aimed to explore the associations between HLA-A\B\DRB1 polymorphisms and the risks of vulvar lichen sclerosus (VLS) or squamous cell hyperplasia of the vulva (SCHV) in Han Chinese women. We enrolled 76 Han Chinese women with VLS (Group A), 74 with SCHV (Group B), and 66 healthy women (control group) in this study. Polymerase chain reaction amplification with sequence specific primers (PCR-SSP) was used to determine HLA-A\B\DRB1 polymorphisms. Compared with the control group, HLA-A*11, -B*15, and -DRB1*12 were present at a higher frequency in groups A and B, while HLA-B*13 was present at a higher frequency in group A. Fewer women in group A carried HLA-A*31, -DRB1*01, and -DRB1*03 genotypes and fewer women in group B carried HLA-B*40 and -DRB1*03 genotypes. Significant differences were found between group B and the control group for HLA-A*11, -B*15, -B*40, and -DRB1*03, and between group A and the control group for HLA-B*15 and -DRB1*12. The HLA-A*11, HLA-B*13, HLA-B*15, and HLA-DRB1*12 genotypes were associated with a higher risk of VLS, while the HLA-A*31, HLA-DRB1*01, and HLA-DRB1*03 genotypes were associated with a lower risk of VLS. In addition, carrying HLA-A*11, HLA-B*15, HLA-B*35, and HLA-DRB1*12 genotypes, and carrying HLA-B*40 and HLA-DRB1*03 genotypes were found to be risk or protective factors for SCHV, respectively.

Development of novel chloroplast microsatellite markers for Ginkgo biloba.

Ginkgo biloba is considered to be a living fossil that can be used to understand the ancient evolutionary history of gymnosperms, but little attention has been given to the study of its population genetics, molecular phylogeography, and genetic resources assessment. Chloroplast simple sequence repeat (cpSSR) markers are powerful tools for genetic studies of plants. In this study, a total of 30 perfect cpSSRs of Ginkgo were identified and characterized, including di-, tri, tetra-, penta-, and hexanucleotide repeats. Fifteen of 21 designed primer pairs were successfully amplified to yield specific polymerase chain reaction products from 16 Ginkgo cultivars. Polymorphic cpSSRs were further applied to determine the genetic variation of 116 individuals in 5 populations of G. biloba. The results showed that 24 and 76% genetic variation existed within and among populations of this species, respectively. These polymorphic and monomorphic cpSSR markers can be used to trace the origin and evolutionary history of Ginkgo.

Functional characterization of the Ginkgo biloba chalcone synthase gene promoter in transgenic tobacco.

The regulative sequence (2273 bp) of the chalcone synthase gene promoter of biloba was cloned by genomic walking. A 2273-bp promoter 5' upstream translation start site of GbCHS was cloned and designated as GbCHSP. pBI121+CHSP:GUS and pBI121-35S:GUS were constructed and transformed into tobacco by LBA4404. We found that GbCHSP could drive transient expression of GUS in tobacco and differentially expressed in root, stem and leaf tissues of this plant. GUS activity regulated by the CHSP promoter were located in tissues (apical meristems) at the growing points of roots and stems. pBI121+CHSP:GUS could be induced by wounding, copper, UV-B, abscisic acid, and ethephon treatments of transgenic seedlings. This activity was weakly inhibited by gibberellin. Deletion analysis of the CHSP promoter in transgenic tobacco showed that CHSP1 complete promoter conferred a GUS expression and activity similar to that of 35 S(CaMV). GUS activity dropped dramatically when there were CHSP4, CHSP5 constructs and was almost totally absent when the CHSP6 construct was present. We conclude that the upstream sequence -1548 to -306 of GbCHSP is the main region for transcriptional regulation of the CHS gene and that it is activated by hormone and stress factors in G. biloba. These results will help us to understand the transcriptional regulatory mechanisms involved in GbCHS expression and flavonoid accumulation in G. biloba.

An efficient approach to identify Ginkgo biloba cultivars by using random amplified polymorphic DNA markers with a manual cultivar identification diagram strategy.

Cultivar identification is a key step to avoid the formation of homonyms and synonyms of Ginkgo biloba. In this study, a new approach based on combinational utilization of polymorphic bands produced from 6 different random amplified polymorphic DNA (RAPD) primers was developed for identifying 42 Ginkgo cultivars, and a manual cultivar identification diagram that consisted of polymorphic bands produced from different RAPD primers was reported. To check the reliability and efficiency of the cultivar identification diagram, 5 randomly chosen cultivars were further tested, and the workability of the diagram was verified. This new approach will be very helpful for Ginkgo cultivar discrimination and protection, and will also be beneficial for the nursery industry for early identification of Ginkgo seedlings.

Endothelial nitric oxide synthase gene polymorphisms and essential hypertension in Han Chinese.

We examined the effect of polymorphisms in the endothelial nitric oxide synthase gene on the risk for essential hypertension in a Han Chinese population through a meta-analysis of data from 15 studies. Associations between increased risk for essential hypertension and 4b/a were obtained in a dominant model and allele contrast (aa + ab vs bb: odds ratio (OR)(FE) = 1.26, 95% confidence interval (CI) = 1.10-1.44; a vs b allele: OR(FE) = 1.23, 95%CI: 1.09-1.40). Four studies with sample sizes over 500 produced similar results. No evidence of publication bias was found. Also, no significant heterogeneity was observed among these studies. When we examined the G894T polymorphism, we found a marginally significant association for allele contrast and the recessive model when all the eligible studies were pooled together. However, there was no evidence for a significant association after the exclusion of two studies deviating from Hardy-Weinberg equilibrium in the control group. Heterogeneity among studies was observed. Results of cumulative and recursive cumulative meta-analysis indicated that more studies are needed to objectively determine the effects of these two polymorphisms.