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Dendrobium plants are important commercial herbs in China, widely used in traditional medicine and ornamental horticulture. In this study, sequence-related amplified polymorphism (SRAP) markers were applied to molecular phylogeny analysis and species identification of 31 Chinese Dendrobium species. Fourteen SRAP primer pairs produced 727 loci, 97% of which (706) showed polymorphism. Average polymorphism information content of the SRAP pairs was 0.987 (0.982-0.991), showing that plenty of genetic diversity exists at the interspecies level of Chinese Dendrobium. The molecular phylogeny analysis (UPGMA) grouped the 31 Dendrobium species into six clusters. We obtained 18 species-specific markers, which can be used to identify 10 of the 31 species. Our results indicate the SRAP marker system is informative and would facilitate further application in germplasm appraisal, evolution, and genetic diversity studies in the genus Dendrobium.

Premise of the Study: Expressed sequence tag (EST)-derived simple sequence repeat (SSR) markers were developed in Dendrobium officinale by screening a cDNA library. The loci were verified by sequencing and explored for polymorphism among 19 genotypes and transferability among 30 other distantly related Dendrobium species. •, Methods and Results: One hundred ten EST-SSRs were developed, and a set of 20 amplified two to six nucleotide repeats with a mean number of 2.5 alleles per locus and with an observed heterozygosity and polymorphism information content per locus ranging from 0.3463 to 0.9003 and 0.0997 to 0.6537 in 19 D. officinale genotypes, respectively. Furthermore, 92 of these markers have cross-taxa transferability, ranging from 6.45% to 100% among 30 other distantly related Dendrobium species. •, Conclusions: The developed markers have potential for application in germplasm appraisal, genetic diversity study, genetic mapping, and molecular breeding in D. officinale and other congeneric species.

Amplified fragment length polymorphism (AFLP) was assessed in 13 Chinese species of Dendrobium. Three primer combinations E+ACT/M+CAC, E+AAC/M+CAC and E+ACA/M+CAC were used for selective amplification. Between 100 bp and 300 bp, a totle of 346 fragments were detected, in which 342 are polymorphic. The rate of polymorphism was 98.8%. The AFLP data were analyzed using Nei & Li similarity coefficient and UPGMA Cluster method. The result indicated that the 13 species were clustered into three groups on coefficient level 0.54. Group I included D. falconeri, D. officinale, D. wilsonii, D. hercoglossum, D. crystallinum. D. hancockii, D. guangxiense, D. primulinum, D. crepidatum, D. thyrsiflorum. Group II included D. chrysotoxum. Group III included D. loddigesii. This outcome was corresponding to the classification result by using the traditional method. It is concluded that AFLP markers can be used on the studies of genetic relationships and classification of Dendrobium.

Abstract: The genetic diversity of the genus Dendrobium is not well known and the phylogenetic relationship of Dendrobium species are mainly determined by studies of the comparative vegetative anatomy and plant systematics. In the present study, we used the technique of inter-simple sequence repeats (ISSRs) to evaluate genetic diversity and phylogenetic relationship among 31 Dendrobium species from Yunnan region of China. In total, 2368 bands were amplified by 17 ISSR primers, resulting from 278 ISSR loci with 100% polymorphism at genus level. Thirty-one species were unequivocally distinguished based on ISSR fingerprinting. Species-specific ISSR markers were identified in nine of 31 tested Dendrobium species. Unweighted pair-group mean analysis (UPGMA) showed that 31 Dendrobium species were grouped into six clusters, indicating the genus was polyphyletic with several well-supported lineages. The high polymorphism and reliable amplification across species demonstrated the utility of ISSR marker for species diagnosis and genetic diversity study of the genus Dendrobium. [Copyright &y& Elsevier]

Highlights: [•] A full-length D. nobile cDNA library was constructed and 1835 ESTs were obtained. [•] One hundred seventy novel EST-SSRs were developed in D. nobile. [•] A set of 142 EST-SSRs showed robust transferability among 31 Dendrobium species. [•] The genetic diversity showed wide genetic differentiation of section Dendrobium. [•] The phylogeny analysis revealed different genetic architecture among sections. [Copyright &y& Elsevier]

Abstract: The genome organization of Dendrobium species remains largely unexplored. An F1 family derived from the controlled interspecific hybridization between Dendrobium moniliforme and D. officinale were used to create genetic linkage maps of parental Dendrobiums using double pseudo-testcross strategy. A total of 422 markers, including 66 EST-SSR, 126 SRAP, 74 ISSR, and 156 RAPD markers, showed expected Mendelian segregation ratio and were used for genetic map construction. Genetic linkage groups with Kosambi genetic distances were constructed using a LOD score≥4 and a recombination threshold of 0.4. The map of D. moniliforme was 1127.9cM in total length with 165 marker loci distributed in 17 linkage groups; and the D. officinale map consisted of 19 genetic linkage groups with a total length of 1210.9cM positioned by 169 marker loci. The genetic maps constructed in this study can serve as a reference linkage map of Dendrobium species for efficient studies of comparative genetics, genetic mapping of traits with economic interest, and marker-assisted selection in horticultural breeding. [Copyright &y& Elsevier]