ABSTRACT
Sedumjinglanii, a new species of Crassulaceae from Mount Danxia in Guangdong, China, is described and illustrated. Phylogenetic analysis based on the internal transcribed spacer (ITS) region of nrDNA suggests that the new species belongs to S.sect.Sedum sensu Fu and Ohba (2001) in the "Flora of China", and is sister to a clade comprising S.alfredi and S.emarginatum with high support values (SH-aLRT = 84, UFBS = 95) but is distantly related to S.baileyi. The new species is morphologically similar to S.alfredi but it can be distinguished from the latter in its opposite leaves (vs. alternate leaves), its usually wider leaves (0.4-1.2 cm vs. 0.2-0.6 cm), its usually shorter petals (3.4-4.5 mm vs. 4-6 mm), its shorter nectar scales (0.4-0.5 mm vs. 0.5-1 mm), its shorter carpels (1.5-2.6 mm vs. 4-5 mm), and its shorter styles (0.6-0.9 mm vs. 1-2 mm). The new species can be easily distinguished from S.emarginatum which both have opposite leaves by its short, erect or ascending rhizome (vs. long and prostrate rhizome in the latter), shorter petals (3.4-4.5 mm vs. 6-8 mm) and shorter carpels (1.5-2.6 mm vs. 4-5 mm). It can also be easily distinguished from S.baileyi by its short, erect or ascending rhizome (vs. long and prostrate rhizome) and its shorter style (0.6-0.9 mm vs. 1-1.5 mm).
ABSTRACT
Viola huizhouensis (Violaceae), a new species from Xiangtoushan National Nature Reserve of Guangdong Province in China, is described and illustrated. The new species is most similar to V. guangzhouensis, but it can be easily distinguished by its much stouter rhizome, lack of aerial stem, dense pubescence of the basal pedicel and the whole plant. Our phylogenetic analysis, based on ITS sequences, confirms that the new species belongs to V. sect. Diffusae.
ABSTRACT
Rhodoleia Champion ex Hooker is one of the most primitive relict genera of Hamamelidaceae, a key family exploited to understand the origin and early evolution of flowering plants. Genomic simple sequence repeats (SSRs) were developed for R. championii to perform genetic diversity, phylogeographical structure or even systematic evolution studies of the genus. Among the 278,743 contigs (105,758,242 bps) de novo assembled from the low-coverage whole genome sequencing of R. championii, a total of 9106 SSRs were detected in 8370 contigs, and SSR primer pairs were successfully designed for 6677 SSRs. Among the 110 selected primer pairs, 41 were amplified successfully in the preliminary test of SSR screening. Further amplification of these 41 primer pairs across the 122 individuals collected from six populations of the three Rhodoleia species showed that 32 and 40 SSR markers can be amplified in Vietnam and Jinping populations of R. parvipetala, 41, 33, and 41 SSR markers in Boluo, Hongkong and Xinyi populations of R. championii, 25 SSR markers in Fugong population of R. forrestii, and 20 SSR markers demonstrated to be polymorphic across the three species. Genetic analysis for these 20 polymorphic SSRs showed that Allele number (A) ranged from four to 13 and polymorphic information content (PIC) ranged from 0.479 to 0.876 across the three species. At the population level, observed heterozygosity (HO) ranged from 0.000 to 1.000, and expected heterozygosity (HE) ranged from 0.091 to 0.851. In the present study, we provided the first whole-genome sequencing database for the species R. championii, identified ample SSR loci with designed primers, and revealed that 20 of the 110 selected SSRs were polymorphic across three Rhodoleia species. These provide valuable resources for future studies on genetic study, species delimitation, phylogeography, and conservation of this genus.
Subject(s)
Microsatellite Repeats , Trees/classification , Whole Genome Sequencing/methods , DNA, Plant/genetics , Linkage Disequilibrium , Species Specificity , Trees/geneticsABSTRACT
Fokienia hodginsii is a Tertiary relict conifer of the monotypic genus Fokienia (Cupressaceae s.l.). Currently, the species is distributed in southern China, northern Vietnam, and northern Laos and listed as a "near threatened" species by the IUCN. In this study, a total of 427 individuals of F. hodginsii were sampled from China and Vietnam to characterize its genetic diversity and population differentiation. Based on the profiles of 12 simple sequence repeat (SSR) markers, we observed a high level of genetic diversity in F. hodginsii at the species level (H e =0.635), albeit slightly lower than that of its sister species Chamaecyparis obtusa. Signals of bottleneck events were detected in the populations GXDMS, GXHJ, V-PXB, and V-HB, probably due to Pleistocene glaciations or overexploitation in recent years. Pronounced genetic differentiation (F st = 0.157) was found in this species. The inbreeding index (F is = 0.176 ± 0.024) indicated that F. hodginsii has a mixed mating system. Significant correlation was found between the pairwise genetic differentiation and geographic distance (r = 0.882, p = 0.01), suggesting that genetic differentiation among the populations follows the model of isolation by distance (IBD). STRUCTURE analysis and principal coordinate analysis revealed that these populations were divided into four groups: the western China group located mainly in the Yunnan-Guizhou Plateau, the central China group located mostly in the Luoxiao Mountains and Nanling Mountains, the eastern China group located in the Wuyi Mountains and the Vietnam group containing two populations in Vietnam. The different terrains and elevations of populations may be the most likely factors leading to the differentiation between the western China group and the central China group, while the geographic isolation caused by the lack of appropriate habitats may greatly contribute to the differentiation between the central China group and the eastern China group. Based on the results, some conservation suggestions for this species are provided, such as establishing seed orchards and multiple nature reserves.
ABSTRACT
PREMISE OF THE STUDY: Hamamelis mollis (Hamamelidaceae) is a Tertiary relict species endemic to southern China. Polymorphic microsatellite markers were developed to reveal the genetic diversity of this species. METHODS AND RESULTS: The genome of H. mollis was sequenced and de novo assembled into 642,351 contigs. A total of 72,097 paired primers were successfully designed from 80,282 simple sequence repeat (SSR) markers identified in 63,419 contigs. PCR amplification showed that 96 of the 136 synthesized primers could be successfully amplified, and 22 demonstrated polymorphism. The mean number of alleles, levels of observed heterozygosity, and levels of expected heterozygosity were 4.602 ± 0.140, 0.632 ± 0.020, and 0.696 ± 0.010, respectively. The majority of the 96 primer pairs could be amplified in at least one other Hamamelidaceae species, including Distylium myricoides (60), Loropetalum chinense (39), Exbucklandia populnea (24), and E. tonkinensis (24). CONCLUSIONS: These microsatellite loci provide abundant genomic SSR markers to evaluate genetic diversity of this woody ornamental plant.
