Sequence-related amplified polymorphism (SRAP) markers were used to investigate the genetic diversity among 30 populations of Toona ciliata Roem. sampled from the species' distribution area in China. To analyze the polymorphism in the SRAP profiles, 1505 primer pairs were screened and 24 selected. A total of 656 SRAP bands ranging from 100 to 1500 bp were acquired, of these 505 bands (77%) were polymorphic. The polymorphism information content (PIC) values ranged from 0.32 to 0.45, with an average of 0.41. An analysis of molecular variance (AMOVA) indicated that the most significant variation was attributable to differences among the populations and that variation within the populations was OPEN ACCESSForests 2015, 6 1095 small. STRUCTURE analysis divided the 30 populations into two parts. The unweighted pair group method of arithmetic averages (UPGMA) clustering and principal coordinates analysis (PCoA) showed that the 30 populations could be classified into four types. The results demonstrate a clear geographical trend for T. ciliata in China and provide a theoretical basis for future breeding and conservation strategy of T. ciliata.

Neolamarckia cadamba is a fast-growing and deciduous tropical hardwood with anatomical, morphological, and chemical characteristics that make it suitable for building materials, pulp production, and medicine raw materials. In this study, a protocol for direct adventitious shoot organogenesis and plant regeneration from the aseptic cotyledons of N. cadamba was established. The cotyledons with petioles from 3-week-old seedlings were used for adventitious shoot induction in DCR medium containing 22.20 µM 6-benzyladenine (BA) and 0.27 µM α-naphthaleneacetic acid (NAA). The frequency of adventitious shoot induction was 54.2%. Micro-shoots were then transferred to MS medium containing 4.44 µM BA and 0.25 µM indole-3-butyric acid (IBA) for shoot propagation. Available shoots per explant reached 5.9. The highest rooting percentage (98.3%) was obtained when shoots were transferred to half-strength MS medium supplemented with 0.27 µM NAA and 0.25 µM IBA. The rooted plantlets could be successfully acclimatized to a greenhouse with more than 95% survival, and the regenerated plants showed the same morphological characteristics as those of the control plants in fields. Histological observations revealed that the adventitious shoots only originated from the epidermal tissue around the edge of the cut zone of the cotyledonary petiole.

BackgroundPatterns of genetic divergence between populations of facultative metallophytes have been investigated extensively. However, most previous investigations have focused on a single plant species making it unclear if genetic divergence shows common patterns or, conversely, is species-specific. The herbs Rumex acetosa L. and Commelina communis L. are two pseudo-metallophytes thriving in both normal and cupriferous soils along the middle and lower reaches of the Yangtze River in China. Their non-metallicolous and metallicolous populations are often sympatric thus providing an ideal opportunity for comparative estimation of genetic structures and divergence under the selective pressure derived from copper toxicity.ResultsIn the present study, patterns of genetic divergence of R. acetosa and C. communis , including metal tolerance, genetic structure and genetic relationships between populations, were investigated and compared using hydroponic experiments, AFLP, ISSR and chloroplast genetic markers. Our results show a significant reduction in genetic diversity in metallicolous populations of C. communis but not in R. acetosa . Moreover, genetic differentiation is less in R. acetosa than in C. communis , the latter species also shows a clustering of its metallicolous populations.ConclusionsWe propose that the genetic divergences apparent in R. acetosa and C. communis , and the contrasting responses of the two species to copper contamination, might be attributed to the differences in their intrinsic physiological and ecological properties. No simple and generalised conclusions on genetic divergence in pseudo-metallophytes can thus be drawn.

Abstract:The uncertainty about whether, in China, the genus Melia (Meliaceae) consists of one species (M. azedarach Linnaeus) or two species (M. azedarach and M. toosendan Siebold & Zuccarini) remains to be clarified. Although the two putative species are morphologically distinguishable, genetic evidence supporting their taxonomic separation is lacking. Here, we investigated the genetic diversity and population structure of 31 Melia populations across the natural distribution range of the genus in China. We used sequence-related amplified polymorphism (SRAP) markers and obtained 257 clearly defined bands amplified by 20 primers from 461 individuals. The polymorphic loci (P) varied from 35.17% to 76.55%, with an overall mean of 58.24%. Nei's gene diversity (H) ranged from 0.13 to 0.31, with an overall mean of 0.20. Shannon's information index (I) ranged from 0.18 to 0.45, with an average of 0.30. The genetic diversity of the total population (H t ) and within populations (H s ) was 0.37˘0.01 and 0.20˘0.01, respectively. Population differentiation was substantial (Gst = 0.45), and gene flow was low. Of the total variation, 31.41% was explained by differences among putative species, 19.17% among populations within putative species, and 49.42% within populations. Our results support the division of genus Melia into two species, which is consistent with the classification based on the morphological differentiation.

Machilus pauhoi Kanehira is an important timber species in China. A provenance trial was recently set up to evaluate the growth performance of trees from different localities, with the aim of designing seed transfer guidelines. Here, we tested twelve nuclear microsatellite markers derived from other species of the Lauraceae family and investigated population genetic structure in M. pauhoi. Both the number of observed alleles per locus (Na) and the polymorphic information content (PIC) significantly decreased against the latitude, but showed an insignificant decrease against the longitude. Heterozygosity (Ho) and gene diversity (h) exhibited a weak correlation with geographic location. Private alleles were present in multiple populations, and a moderate level of population genetic differentiation was detected (Gst = 0.1691). The joint pattern of genetic diversity (Na, PIC, Ho, and h) suggests that general northeastward dispersal led to the current distribution of M. pauhoi. Significant but weak effects of isolation-by-distance (IBD) occurred, implicating the mountain ranges as the major barrier to gene flow. Both STRUCTURE and hierarchical clustering analyses showed three distinct groups of populations related to the physical connectivity among mountain ranges. A priority in designing genetic conservation should be given to the populations at the southwest side of the species’ distribution. This conservation strategy can also be combined with the pattern of adaptive genetic variation from the provenance trial for comprehensive genetic resource management of native M. pauhoi.

Morinda officinalis How (Rubiaceae) is well known as one of the four most popular medicinal plants in the southern region of China. In order to assess its genetic diversity and assist the development of its molecular assisted-selection breeding in China, we constructed the transcriptome database of M. officinalis using fresh leaf material and developed novel expressed sequence tag-simple sequence repeat (EST-SSR) markers for this important medicinal plant species. Our study identified 8064 potential EST-SSRs from 6668 unigenes. For perfect repeat motifs, the mononucleotide repeats were most abundant (4221; 52.34%), followed by the trinucleotide repeats (1588; 19.69%), and the dinucleotide ones (1040; 12.90%). The seven most commonly occurring repeat motifs were A/T (4661), AG/CT (588), AAG/CTT (408), AC/GT (353), ATC/ATG (338), AT/AT (296) and AGG/CCT (277). Of a total of 5605 SSR primer sets that were successfully designed de novo, 100 were selected for validation analysis. There, 24 primer sets were polymorphic across the 96 M. officinalis individuals collected from four different populations in Guangdong province. Based on cross-species transferability test, 19 and 22 primer sets produced successful amplification in M. umbellata subsp. obovata and M. parvifolia, respectively. These novel EST-SSR markers with high cross-species transferability between M. officinalis and its closely-related species could serve as aids to future studies in genetic diversity, conservation, assisted-selection breeding and genes associated with the medical uses of the genus.

Forests suffer from heavy losses due to the occurrence of fires. A prediction model based on environmental condition, such as meteorological and vegetation indexes, is considered a promising tool to control forest fires. The construction of prediction models can be challenging due to (i) the requirement of selection of features most relevant to the prediction task, and (ii) heavily imbalanced data distribution where the number of large-scale forest fires is much less than that of small-scale ones. In this paper, we propose a forest fire prediction method that employs a sparse autoencoder-based deep neural network and a novel data balancing procedure. The method was tested on a forest fire dataset collected from the Montesinho Natural Park of Portugal. Compared to the best prediction results of other state-of-the-art methods, the proposed method could predict large-scale forest fires more accurately, and reduces the mean absolute error by 3–19.3 and root mean squared error by 0.95–19.3. The proposed method can better benefit the management of wildland fires in advance and the prevention of serious fire accidents. It is expected that the prediction performance could be further improved if additional information and more data are available.

Premise of the study:The genus Anneslea (Pentaphylacaceae) contains four species and six varieties, most of which are locally endemic. Here, simple sequence repeat (SSR) markers were developed for the conservation of these species.Methods and Results:The genome of A. fragrans was sequenced and de novo assembled into 445,162 contigs, of which 30,409 SSR loci were detected. Primers for 100 SSR loci were validated with PCR amplification in three populations of A. fragrans. Seventy-nine loci successfully amplified, and 30 were polymorphic. The mean number of alleles, observed heterozygosity, and expected heterozygosity were 7.01 ± 1.60, 0.817 ± 0.241, and 0.796 ± 0.145, respectively. Most primers could be amplified in Ternstroemia gymnanthera, T. kwangtungensis, and Cleyera pachyphylla.Conclusions:Our study demonstrated that shotgun genome sequencing is an efficient way to develop genomic SSR markers for nonmodel species. These genomic SSR loci will be valuable in population genetic studies in Anneslea and its relatives.