BackgroundChinese bayberry (Myrica rubra Sieb. and Zucc.) is a subtropical evergreen tree originating in China. It has been cultivated in southern China for several thousand years, and annual production has reached 1.1 million tons. The taste and high level of health promoting characters identified in the fruit in recent years has stimulated its extension in China and introduction to Australia. A limited number of co-dominant markers have been developed and applied in genetic diversity and identity studies. Here we report, for the first time, a survey of whole genome shotgun data to develop a large number of simple sequence repeat (SSR) markers to analyse the genetic diversity of the common cultivated Chinese bayberry and the relationship with three other Myrica species.ResultsThe whole genome shotgun survey of Chinese bayberry produced 9.01Gb of sequence data, about 26x coverage of the estimated genome size of 323 Mb. The genome sequences were highly heterozygous, but with little duplication. From the initial assembled scaffold covering 255 Mb sequence data, 28,602 SSRs (≥5 repeats) were identified. Dinucleotide was the most common repeat motif with a frequency of 84.73%, followed by 13.78% trinucleotide, 1.34% tetranucleotide, 0.12% pentanucleotide and 0.04% hexanucleotide. From 600 primer pairs, 186 polymorphic SSRs were developed. Of these, 158 were used to screen 29 Chinese bayberry accessions and three other Myrica species: 91.14%, 89.87% and 46.84% SSRs could be used in Myrica adenophora, Myrica nana and Myrica cerifera, respectively. The UPGMA dendrogram tree showed that cultivated Myrica rubra is closely related to Myrica adenophora and Myrica nana, originating in southwest China, and very distantly related to Myrica cerifera, originating in America. These markers can be used in the construction of a linkage map and for genetic diversity studies in Myrica species.ConclusionMyrica rubra has a small genome of about 323 Mb with a high level of heterozygosity. A large number of SSRs were identified, and 158 polymorphic SSR markers developed, 91% of which can be transferred to other Myrica species.

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Abstracts A collection of 122 Chinese bayberry accessions and one wax myrtle (Myrica cerifera L.) were analyzed with 14 polymorphic simple sequence repeats (SSRs). The average number of alleles per locus was 9.3, and polymorphism information content varied from 0.07 to 0.83, with a mean value of 0.62. The genetic relationships among the 123 accessions were analyzed using the unweighted pair-group method with arithmetic mean (UPGMA). The similarity among all the accessions, based on Dice's coefficient, varied from 0.78 to 0.99, and 0.74 between the Chinese bayberries and wax myrtle. A set of 122 Chinese bayberries clustered into four groups, with the first group further divided into six subgroups. The accessions originating from the same geographical region were more closely related than those from different regions, although extensive gene flow has taken place. The Mantel test, used to compare similarity matrices calculated from AFLP and SSR data, showed that their combination could provide information on the genetic relationship among the Chinese bayberry accessions. Ten selected SSR markers were able to distinguish most accessions, and multiplex PCR systems were developed. In addition, we found that SSRs developed from Chinese bayberry are transferable to M. cerifera.

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is one of the important subtropical fruit crops native to the South of China and Asian countries. In this study, 107 novel simple sequence repeat (SSR) molecular markers, a powerful tool for genetic diversity studies, cultivar identification, and linkage map construction, were developed and characterized from whole genome shotgun sequences. M13 tailing for forward primers was applied as a simple method in different situations. In total, 828 alleles across 45 accessions were detected, with an average of 8 alleles per locus. The number of effective alleles ranged from 1.22 to 10.41 with an average of 4.08. The polymorphic information content (PIC) varied from 0.13 to 0.89, with an average of 0.63. Moreover, these markers could also be amplified in their related species Myrica cerifera (syn. Morella cerifera) and Myrica adenophora. Seventy-eight SSR markers can be used to produce a genetic map of a cross between 'Biqi' and 'Dongkui'. A neighbor-joining (NJ) tree was constructed to assess the genetic relationships among accessions, and the elite accessions 'Y2010-70', 'Y2012-140', and 'Y2012-145', were characterized as potential new genotypes for cultivation.

Novel compact microstrip quint‐mode multi‐stub‐loaded resonator has been investigated. Meanwhile, its applications to the dual‐band bandpass filter (BPF) and quad‐channel diplexer have also been proposed. The proposed dual‐band BPF is constructed by a single quint‐mode resonator, leading to a very small circuit size. Herein, the first three resonant modes are used to form the first passband, while the other two are used to form the second passband. Besides, the proposed quad‐channel diplexer is constructed by two different quint‐mode resonators, which also occupies a very small circuit size. In this diplexer design, one of the quint‐mode resonator is used to realise the passbands for channels 1 and 3, and the other one is used to realise the passbands for channels 2 and 4. For demonstration, a dual‐band BPF operating at 0.9 and 2.2 GHz with a size of 0.17λg × 0.23λg and a quad‐channel diplexer operating at 0.9, 1.45, 2.1, and 2.7 GHz with a size of 0.28λg × 0.23λg have been designed, fabricated, and measured. The electromagnetic simulated and measured results are in good agreement.