Zheng-Feng Wang

Characteristics of sun- and shade-adapted populations of an endangered plant Primulina tabacum Hance

Primulina tabacum Hance is an endangered perennial herb distributed in calcium-rich and nitrogen-limited soil of the karst limestone areas in southern China. The morphological, ultrastructural, and physiological traits were determined for P. tabacum populations growing in three different environment conditions: twilight zone of a cave (site TZ, extremely low light intensity), at a cave entrance (site EZ, low light intensity), and in an open area (site OA, high light intensity). At site OA, P. tabacum plants were exposed to high light (635 μmol m−2 s−1 of mean daily photosynthetically active radiation) with drought stress, and expressed traits to minimize light capture and water loss. Compared to plants at sites EZ and TZ, those at site OA had thicker leaves with higher densities of stomata and pubescence, higher palisade/spongy ratio, higher light-saturated rate of net photosynthetic rate (Pmax), higher biomass, higher non-photochemical quenching coefficient (NPQ), and higher light saturation point (LSP) but fewer grana per chloroplast and less thylakoid stacking per granum. In contrast, P. tabacum growing at the cave vicinities: EZ (mean daily irradiance 59 μmol m−2 s−1) and TZ (mean daily irradiance 11 μmol m−2 s−1) showed typical shade-adapted characteristics for optimum light capture. The presence of sun- and shade-adapted characteristics indicates that P. tabacum has different strategies to cope with different environments but whether these strategies reflect genetic selection or phenological plasticity is yet to be determined. Such variability in physiological and morphological traits is important for the survival of P. tabacum in heterogeneous light conditions.

Isolation and characterization of microsatellite markers for Primulina tabacum, a critically endangered perennial herb

Primulina tabacum is a rare and endangered perennial herb with highly restricted limestone distribution in southern China. To enrich our scientific conservation for this species, we developed ten microsatellite markers using repetitive DNA enriched libraries. The number of alleles per microsatellite locus varied from two to six. The expected (HE) and observed (HO) heterozygosities varied from 0.4059 to 0.7294 and from 0.1364 to 0.5217, respectively. These markers will be employed in future studies of genetic structure in P. tabacum.

Isolation and characterization of microsatellite loci in endangered Cycas changjiangensis (Cycadaceae).

Eight microsatellite loci were isolated from repetitive DNA enriched libraries for Cycas changjiangensis, an endangered endemic species in Hainan Island, China. The number of allele ranged from three to seven. The observed (HO) and expected (HE) heterozygosities ranged from 0.0000 to 0.8750 and from 0.2359 to 0.7582, respectively. These microsatellite loci will enrich our scientific understanding for C. changjiangensis conservation.

Identification and characterization of EST-SSRs and cpSSRs in endangered Cycas hainanensis

We report on the identification and characterization of six EST-linked simple sequence repeats (EST-SSRs) and chloroplast SSRs (cpSSRs) in endangered Cycas hainanensis. The number of alleles ranged from two to eight for EST-SSRs, two to three for cpSSRs. Observed and expected heterozygosities ranged from 0.042 to 0.417 and 0.042 to 0.811 for EST-SSRs, respectively. Expected heterozygosities ranged from 0.156 to 0.457 for cpSSRs. All these markers gave successful cross-species amplification in C. fairylakea. These markers will allow analyses of the baseline genetic variability and population structure of C. hainanensis to provide strategies for effective conservation and management.

Pollen and seed flow under different predominant winds in wind-pollinated and wind-dispersed species Engelhardia roxburghiana

In most plants, the contributions of pollen and seed flow to their genetic structures are generally difficult to disentangle. For typical wind-pollinated and wind-dispersed species Engelhardia roxburghiana in a 20-ha natural forest plot in lower subtropic China, because the prevailing wind directions change during its pollen release and seed dispersal seasons, we could compare its genetic structures in different directions, which could result primarily from pollen or seed flow. Furthermore, because the plot has undergone from an open to a closed canopy stage historically, we also examined forest canopy effects on gene flow in different generations and different directions. Using 522 E. roxburghiana individuals mapped in the plot, our results revealed that greater pollen flow led to biased gene flow in the pollen dispersal-predominant direction (pollen direction), while greater seed flow generated less spatial genetic structure in the seed dispersal-predominant direction (seed direction). The results predicted from generalized additive models indicated that canopy closure enhanced resistance to gene flow from the old generation to the new generation. Analyses by landscape genetic models for the new generation revealed that gene flow associated with pollen direction was more strongly affected by canopy than with seed direction. Our study is new by proposing an alternative way to separate effects of the pollen and seed flow on spatial variation patterns in E. roxburghiana. To our knowledge, our study is also the first attempt to use landscape genetic models to represent canopy effects for different dispersal vectors in spatial scales only up to a few hundred meters.

Genetic variation of Ardisia crenata in south China revealed by nuclear microsatellite.

Abstract  Ardisia crenata Sims, one of the most widely distributed Ardisia in the world, is an important ornamental and medicinal plant species. Using seven polymorphic nuclear microsatellite loci, we studied the genetic variation of 20 natural populations of A. crenata across its distribution center in south China. Significant deviation from the Hardy–Weinberg equilibrium in all populations and at all loci were detected, and the fixation index was high (FIS= 0.725), indicating that inbreeding may be dominant in the mixed mating system of this self‐compatible species. The average genetic diversity within populations was relatively low (HS= 0.321). There was significant genetic differentiation among populations (FST= 0.583), which may have resulted from a high level of inbreeding and a low level of gene flow. Ardisia crenata in south China can be roughly divided into an eastern group and a western group, consistent with the floristic division of the Sino‐Himalayan forest subkingdom and the Sino‐Japanese forest subkingdom. There may be separated glacial refugia in each region.

Isolation and characterization of 36 polymorphic microsatellite markers in Schima superba (Theaceae).

PREMISE OF THE STUDY Our objective was to develop microsatellite markers to investigate the level of genetic diversity within and among populations in a dominant evergreen broad-leaved tree, Schima superba, in southern China. METHODS AND RESULTS Thirty-six microsatellite markers were developed and showed polymorphism in three populations. The number of alleles per locus ranged from six to 34, with an average of 19. The observed and expected heterozygosities ranged from 0.242 to 1.000 and from 0.504 to 0.945, respectively. CONCLUSIONS The developed microsatellites will be useful for studying genetic diversity and population structure in S. superba.

Isolation and characterization of polymorphic microsatellite loci in Camellia nitidissima Chi (Theaceae).

UNLABELLED PREMISE OF THE STUDY Microsatellite markers were developed in Camellia nitidissima for further population genetic studies. • METHODS AND RESULTS Eight microsatellite markers were newly developed from C. nitidissima and 7 were transferred from other Camellia species. Two to 13 alleles per locus were identified for these microsatellites. Observed and expected heterozygosities ranged from 0.040 to 0.909, and 0.184 to 0.916, respectively. Four loci showed a significant deviation from Hardy-Weinberg equilibrium and five locus pairs displayed linkage disequilibrium. • CONCLUSIONS These microsatellite markers will be useful to assess the genetic variation and genetic structure of C. nitidissima.

Inferring the invasion history of coral berry Ardisia crenata from China to the USA using molecular markers

Genetic comparisons between native and invasive populations of a species can provide insights into its invasion history information, which is useful for guiding management and control strategies. The coral berry Ardisia crenata was introduced to Florida last century as a cultivated ornament plant, and has since spread widely throughout the southern regions of the USA. Previously, the genetic variation among 20 natural populations of A. crenata across its distribution center in southern China was quantified using seven microsatellite markers. Here we expand on that work by additionally sampling individuals from four other native populations in Taiwan and Japan, and from five invasive populations in the USA. We also examined the results from one chloroplast intergenic spacer region (trnF-trnL) in all 29 populations. Our aim is to identify the invasion source and subsequent history of the species’ spread throughout the southern USA. We observed lower genetic diversity in the invasive populations based on both microsatellite and chloroplast markers. Our data show that the invasive populations can be clustered with native populations in southeastern China, inferring this region as the geographic origin of A. crenata cultivars invading the USA. We further classified invasive individuals into invasive I and invasive II clusters. Nantou in Taiwan and Xihu in mainland China are the most closely related populations to those, which identify the former as potential sources for host-specific control agents. Our results, combined with the known introduction records, suggest that A. crenata was first multiply introduced into Florida and then secondarily colonized Louisiana and Texas from Florida.

Development of microsatellite markers for Suriana maritima (Surianaceae) using next-generation sequencing technology.

Our objective was to develop microsatellite markers for use in assessing genetic variation in the small shrub or tree species Suriana maritima (Surianaceae). In China, this species is found only as a few fragmented populations and individuals on the Paracel Islands. Using next-generation genome sequencing methodology, we developed 17 novel microsatellite markers for S. maritima. Fifty-four individuals from six populations of S. maritima were examined for polymorphisms; only one allele was detected for each of the markers. Microsatellite loci developed indicate a complete absence of genetic diversity for S. maritima on the Paracel Islands in China. These markers will be useful for examining genetic variation among S. maritima populations in other areas of the world.