Analysis of Genetic Diversity of Processing Apple Varieties

Genetic diversity of 18 processing apple varieties and two fresh varieties were evaluated using 12 simple sequence repeats （SSR） primer pairs previously identified in Malus domestica Borkh. A total of 87 alleles in 10 loci were detected using 10 polymorphic SSR markers selected within the range of 5-14 alleles per locus. All the 20 varieties could be distinguished using two primer pairs and they were divided into four groups using cluster analysis. The genetic similarity （GS） of groups analyzed using cluster analysis varied from 0.14 to 0.83. High acid variety Avrolles separated from other varieties with GS less than 0.42. The second group contained Longfeng and Dolgo from Northeast of China, the inherited genes of Chinese crab apple. The five cider varieties with high tannin contents, namely, Dabinette, Frequin rouge, Kermerrien, M.Menard, and D.Coetligne were clustered into the third group. The fourth group was mainly composed of 12 juice and fresh varieties. Principal coordinate analysis （PCO） also divided all the varieties into four groups. Juice and fresh apple varieties, Longfeng and Dolgo were clustered together, respectively, using both the analyses. Both the analyses showed there was much difference between cider and juice varieties, cider and fresh varieties, as well as Chinese crab apple and western European crab apple, whereas juice varieties and fresh varieties had a similar genetic background. The genetic diversity and differentiation could be sufficiently reflected by combining the two analytical methods.

Determination of genetic relationships between evergreen azalea cultivars in China using AFLP markers

Evergreen azaleas are among the most important ornamental shrubs in China.Today,there are probably over 300 cultivars preserved in different nurseries,but with little information available on the cultivar itself or relationships between cultivars.Amplified fragment length polymorphism(AFLP) markers were employed to determine the genetic relationships between evergreen azalea cultivars in China.One hundred and thirty genotypes collected from gardens and nurseries,including cultivars classified in the groups East,West,Hairy,and Summer,unknown cultivars,and close species,were analyzed using three primer pairs.A total of 408 polymorphic fragments were generated by AFLP reactions with an average of 136 fragments per primer pair.The average values of expected heterozygosity and Shannon's information index were 0.3395 and 0.5153,respectively.Genetic similarities were generated based on Dice coefficients,used to construct a neighbor joining tree,and bootstrapped for 100 replicates in Treecon V1.3b.Principal coordinate analysis(PCO) was performed based on Dice distances using NTSYS-pc software.The AFLP technique was useful for analyzing genetic diversity in evergreen azaleas.Cluster analysis revealed that cultivars in the West and Summer groups were quite distinct from other groups in the four-group classification system and that the East and Hairy groups should be redefined.

Microbial characteristics in anaerobic membrane bioreactor treating domestic sewage:Effects of HRT and process performance

Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.

Distribution of shrublands in relation to soil and climate in mid-subtropical China

Aims Understanding relationships between vegetation and environments is of importance for ecosystem restoration and management.However,information on how environments influence the floristic patterns of shrublands is lack,especially in the subtropical China.In this study,we explored how environments regulate species composition of shrublands at landscape scale in mid-subtropical China.Methods We investigated species composition and measured the climate and soil environments for 207 shrubland plots in mid-subtropical China(24°39′-30°08′N,108°47′-114°15′E).We applied a hierarchical cluster analysis and indicator species analysis based on the Bray-Curtis similarity index to identify the main shrubland types and employed principal coordinate analysis(PCoA)to explore the relationship between floristic composition and environment.Important Findings We identified four shrubland types occurring in different environmental conditions.Montane shrubland,dominated by species suitable for cool climates(e.g.Rhododendron simsii),were distributed in steep areas at comparatively high altitudes;foothill shrubland,dominated by mesophilous species(e.g.Loropetalum chinense),were distributed in low mountains and hills;pioneer shrubland,dominated by fast grow and short-life cycles species(e.g.Rhus chinensis),were distributed at low altitudes with dense population;and finally,limestone shrubland,dominated by calcicole plants(e.g.Coriaria nepalensis),were distributed in the extensive karst areas.Communities occurring in high pH soils were completely separated from those in low pH soils according to the hierarchical cluster analysis.PCoA ordination associated the four types with distinct edaphic and climatic gradients.Soil pH explained 63.3%of variation in PCoA,followed by soil depth and soil bulk density.