Pinus Bungeana Research Articles

The response system of the growth, physiological and uptake characteristics of Pinus bungeana under ozone stress

Objective: To study the changes of growth, physiological and absorption characteristics of Pinus bungeana under ozone (O3) stress, to elucidate the correlations among the indicators, and to determine its degree of response to O3. Methods: The growth, physiological characteristics and O3 uptake capacity of Pinus bungeana seedlings were measured in an open-top O3 fumigation manual control experiment with three concentration gradients (NF: normal atmospheric O3 concentration, NF40: normal atmospheric O3 concentration plus 40 nmlol/mol; NF80: normal atmospheric O3 concentration plus 80 nmol/mol), and the relationships between the characteristics of Pinus bungeana under different O3 concentrations were investigated with correlation analysis, redundancy analysis and analysis of variance. Results: (1) Plant height growth (ΔH), diameter growth at 50 cm (ΔDBH), stomatal size (S), stomatal density (M), stomatal opening (K), stomatal conductance (Gs), net photosynthetic rate (Pn), transpiration rate (Et), water use efficiency (WUE), maximum photochemical efficiency (Fv/Fm), chlorophyll content (CHL), whole tree water consumption (W), and O3 uptake rate () all decreased with the increase of O3 concentration; while intercellular CO2 concentration () and relative conductivity (L) increased with the increase of O3 concentration; (2) growth indicators of Pinus bungeana under O3 stress (ΔH, ΔDBH) were the most correlated with O3 uptake status (, W), followed by photosynthetic indicators (, WUE, ,, ) and growth indicators (ΔH, ΔDBH) and stomatal characteristics (K, M, S) under O3 stress, some physiological indicators (L, ) were relatively weakly correlated with photosynthesis (, WUE,,, ) and stomatal (K, M, S); (3) all the indicators of Pinus bungeana were significantly different under O3 treatments of NF and NF80 (P < 0.05), ΔH, ΔDBH, M, CHL, , , W and were most significantly different under NF and NF40 treatments, and K, S, WUE, , , , L were more significantly different under NF40 and NF80 treatments. Conclusion: The experiment proved that the growth of Pinus bungeana was slowed, photosynthetic capacity was reduced, and the absorption capacity of O3 was further reduced by long-term exposure to high concentration of O3. The growth of Pinus bungeana was most correlated with the changes of O3 absorption characteristics, and the stomatal characteristics were most correlated with photosynthetic physiological characteristics, and the reduction of photosynthetic capacity etc. further led to the curtailment of its growth.

Revealing the Genetic Structure and Differentiation in Endangered Pinus bungeana by Genome-Wide SNP Markers

Understanding the genetic variation and differentiation of natural populations is essential for their protection, specifically if the species status is endangered as with Pinus bungeana. Here, we used 346,840 high density and strong specificity SNP loci to carry out genetic analyses (i.e., genetic diversity, genetic structure, phylogeny, and geographical differentiation) on 52 P. bungeana individuals from 5 populations (4 natural and one artificial) representing the main regions of the species distribution in China. Genetic diversity assessment indicated a trend of genetic diversity gradual decrease from west to east across the species distribution areas. Population genetic structure, PCA and phylogenetic analyses consistently indicated that populations in the central and eastern regions were clustered together, while those from the western regions were separated. Mantel test values indicated the presence of geographic isolation among populations, an important factor contributing to the observed genetic differentiation. The maximum likelihood tree and potential migration events inferred from TreeMix analysis indicated the presence of historical genetic exchanges between the west of Qinling Mountains and the Lvliang Mountains populations. Based on the generated genetic information, in situ and ex situ conservation strategies for P.bungeana germplasm resources are proposed, these strategies could be valuable for the conservation, protection and genetic improvement of this endangered species.

Low genetic diversity and population connectivity fuel vulnerability to climate change for the Tertiary relict pine Pinus bungeana

AbstractEndemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping‐by‐sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global FST 0.234) even at regional scales, reflecting long‐term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction.

Variation characteristics of plant electrical signal and their relationship with negative air ion under different light intensities.

Negative air ion (NAI) is an essential indicator for measuring air cleanliness of a given area, with vital role in regulating psychological and physiological functions of human body. The photoelectric effect is an important source and influencing factor for the generation of NAI during photosynthesis, but the photoelectric effect is extremely weak and difficult to monitor. Plant electrical signal is an important indicator that indirectly reflects photoelectric effect. Previous studies mostly focused on the spatiotemporal variation of NAI in different forest communities and its relationship with meteorological factors. At present, there is little research on NAI and plant electrical signal. In this study, we explored the effect of different light intensities (0, 150, 300, 500, 700, 800, 1000 and 1200 μmol·m-2·s-1) on characteristics of the plant electrical signal and its relationship with negative air ion, with Pinus bungeana as the research object. The results showed that the intensity of plant electrical signal increased significantly with the increases of light intensity in the illumination range of 0-700 μmol·m-2·s-1. When light intensity reached 700 μmol·m-2·s-1, plant electrical signal activity reached the highest level, and plant was inhibited by light when light intensity increased further, with plant electrical signal activity decreased. The frequency-domain parameters (edge frequency, gravity frequency, power spectrum entropy and power spectrum peak) of plant electrical signals were significantly correlated with NAI. The correlation coefficient between edge frequency (E) and NAI was the highest, the relationship between them was NAI=30.981E+168.814 (R2=0.54), and the mean square error was 52.203. There was a significant correlation between plant electrical signals and NAI, which could characterize the change rule of NAI, and provide scientific evidence for further understanding the contribution potential and production mechanism of forest to NAI.

Halogen‐Doped Carbon Dots on Amorphous Cobalt Phosphide as Robust Electrocatalysts for Overall Water Splitting

AbstractDesigning a stable and efficient dual‐functional catalyst for the hydrogen evolution and oxygen evolution reactions (HER/OER) is of great significance to the development of hydrogen production by water splitting. This work reports on novel halogen (X = F, Cl, and Br)‐doped carbon dots modifying amorphous cobalt phosphide (X‐CDs/CoP), which can be tuned by the choice of X‐CDs to have urchin, Pinus bungeana, and Albizia julibrissin type structures. The different characteristics of the various X‐CDs led to different formation mechanisms and final structures. As a bifunctional catalyst, urchin‐shaped F‐CDs/CoP crystals achieve superior electrocatalytic performance, exhibiting excellent HER/OER activity and sustained stability in an alkaline solution. For overall water splitting, they provide current density of 10 mA cm−2 and require a low cell voltage of 1.48 V in 1 M KOH. In addition, the catalytic performance shows negligible degradation after 100 h, thus demonstrating excellent long‐term cycling stability. Density functional theory calculations show that the improved electrocatalytic performance of F‐CDs/CoP catalysts is due to the coupling interface between CoP and F‐CDs, which optimizes the hydrogen/oxygen adsorption energy and accelerates the water splitting kinetics. This work provides guidance for the rational design of transition metal phosphide electrocatalysts with outstanding performance.

Effects of O3 stress on photosynthesis of trees

The effects of elevated O3 (O3) on photosynthetic characteristics of urban trees were studied in an open-top air chamber. The results showed that net photosynthetic rate (Pn), transpiration rate (Et), stomatal conductance (Gs) and water use efficiency (WUE) of different tree species decreased significantly with the increase of O3 concentration, while intercellular CO2 (Ci) concentration of different tree species increased significantly with the increase of O3 concentration. Under different O3 concentrations, the net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration of Ginkgo biloba (G. biloba) and Koelreuteria paniculata (K. paniculata.) were higher than those of Pinus bungeana (P. bungeana) and Platycladus orientalis(P. orientalis), and the WUE of P. bungeana and P. orientalis was higher than that of G. biloba and K. paniculata. The effect of elevated O3 concentration on plant photosynthesis is more obvious in K. paniculata and G. biloba.

Characteristics of tree growth and leaf damage under different O3 concentrations

Pinus bungeana, Platycladus orientalis, Koelreuteria paniculata and Ginkgo biloba were taken to research. 3 open-top chambers with O3 concentration gradient were set up to study the characteristics of tree growth and leaf damage under different O3 concentrations. The results showed that with the increase of O3 concentration, the growth of different tree species were inhibited, but the diameter between different tree species was not significantly different. The plant height of different tree species the plant height of different tree species increased from 0.05m to 0.06m under NF O3 concentration, from 0.01m to 0.03m under NF40 O3 concentration, but from 0.01m to 0.02m under NF80 O3 concentration. The diameter of different tree species at 50cm increased from 0.90cm to 1.40cm under NF O3 concentration, from 0.70cm to 1.00cm under NF40 O3 concentration, and from 0.60cm to 0.80cm under NF80 O3 concentration. Under NF O3 concentration, the leaves of different tree species performed well, without any damage symptoms. With the increase of O3 concentration, leaves were withered and died. Leaves wilted under NF40 O3 concentration, but died and fallen under NF80 O3 concentration. Pinus bungeana and Platycladus orientalis were good at resisting O3 pollution, while Koelreuteria paniculata and Ginkgo biloba were worse. The damage of O3 concentration to plants is more sensitive to broad-leaved trees.

Development of SNP molecular markers of Pinus bungeana based on SLAF-seq technology

Development of SNP molecular markers of Pinus bungeana based on SLAF-seq technology

Geography and climate regime affect needle stoichiometry character of Pinus bungeana across China

Leaf stoichiometric pattern and its potential determinants are of great significance in the modeling nutrient cycling, detecting ecosystem stability and predicting the response of ecosystem to global changes. To reveal the stoichiometric characteristic of Pinus bungeana, we analyzed the needle nitrogen (N) and phosphorous (P) concentrations of 76 needle samples from 15 sampling sites throughout the country, and took the local geographical and climatic variables into consideration. The generalized linear mixed model (GLMM) and principal component analysis (PCA) were used to explore the effects of environmental factors on needle stoichiometry. This study revealed that both the concentrations and ratio of N, P content showed significant differences in needles of P. bungeana among different sampling sites. The needle N, P concentrations and N: P ratio showed quadratic curve correlation with climatic factors. The PCA indicated that all variables can be explained by three principal components, namely, temperature, N and P, which were very important factors affecting the geographical distribution of P. bungeana. Among the three components, N is most crucial factor limiting the growth and metabolism of P. bungeana. In summary, our study will help to elucidate the patterns of needle N and P concentrations in needles of P. bungeana, thus revealing the causes and driving forces for its natural region.

Green-colored paperboard enhances the Asian longhorned beetle response to host plant odor cues

The Asian longhorned beetle (Anoplophora glabripennis) attacks apparently healthy trees, and more effective tools for surveying and monitoring them are needed. To better understand how the beetle recognizes and locates its hosts, we compared adult feeding on and orientation to cut branches of Acer negundo (a preferred host), Salix matsudana, Ailanthus altissima and Pinus bungeana, and found that adults preferred Acer negundo to others. We then evaluated whether color cues enhanced host (A. negundo) odor attractiveness for A. glabripennis. We assessed preference of adult A. glabripennis for colors that mimicked the bark of cut branches and found that adults were significantly attracted by forest green. We examined the effect of plant odors alone and found no significant difference among tested plants; however, the combination of forest green and A. negundo odors was more attractive to adults than combinations of other colors with A. altissima and P. bungeana odors. Finally, we studied the interaction between color and odor to determine their potential influence on A. glabripennis behavior. We found that combinations of cues that included forest green and host odor were more attractive to adults than others, but these preference of adults for forest green was disrupted by A. altissima odors.

Identifying conservation priority areas for gymnosperm species under climate changes in China

China has a rich flora of gymnosperms. Gymnosperm species dominate and co-dominate more than half of China's forest area, but many of them are threatened and vulnerable to climate changes. This study mapped the geographical distributions of 209 gymnosperm species in China, modeled the niches of 124 gymnosperm species with adequate records of field occurrences using MaxEnt, and predicted their range changes under two dispersal scenarios (no dispersal and unlimited dispersal) and three emission scenarios (Representative concentration pathway [RCP] 2.6, RCP 6.0, RCP 8.5). To inform gymnosperm conservation facing climate change, we proposed a multi-criteria framework to identify conservation priority areas by integrating information on species diversity patterns and potential climate refugia, and detected gymnosperm conservation gaps with reference to the existing conservation networks. Our results indicated that the centers of species richness, threatened species, and endemism of gymnosperms in China were highly consistent in space and were concentrated in the subtropical mountains. By the 2070s, 64 (RCP 2.6)–88 (RCP 8.5) species would lose more than 10% of their currently suitable climatic niche, and 19 (RCP 2.6)–45 (RCP 8.5) species would lose more than 30%. Cathaya argyrophylla (endangered, EN), Pinus bungeana (EN), Pinus koraiensis (vulnerable, VU) and Torreya fargesii (VU) would be most vulnerable to the projected climate changes. Seven high conservation priority regions were identified, and a substantial proportion of the regions were found lack of adequate protection. The primary recommended measures included increasing the size of protected areas to cover more high priority regions and establishing populations in new sites as required ex-situ conservation efforts.

The growth law for natural secondary forests of Pinus bungeana in the Huanglong Mountain forest region

The growth law for natural secondary forests of Pinus bungeana in the Huanglong Mountain forest region

Pestalotiopsis trachicarpicola, a novel pathogen causes twig blight of Pinus bungeana (Pinaceae: Pinoideae) in China.

Pinus bungeana is one of indigenous trees in China and widely distributed in poor and arid regions for vegetation and industrial woody use. However, since a high-incidence disease threatens the growth of mature P. bungeana tree in the garden and in the plantation every year, the overwintering shoots were infected and died in the next spring with a ratio over 70%, but the cause was beyond understood. A total of 120 fungal isolates were separated from symptomatic twigs by histological isolation methods, including Pestalotiopsis spp., Fusarium spp., Trichothecium spp., Penicillium and some unknown fungal species. Pestalotiopsis spp. was dominant, accounting for 85%. Morphological observation under microcopy showed all Pestalotiopsis species are identical, and six isolations among them were randomly selected for pathogenicity tests. Fulfilling Koch's postulates showed that all six isolates of Pestalotiopsis spp. were pathogens of twig blight, causing the same symptoms as observed in the field, while other non-Pestalotiopsis isolates were avirulent to P. bungeana twigs. Multi-gene (ITS, tub2 and TEF1) analysis and morphological observation revealed that all the six Pestalotiopsis isolates belonged to P. trachicarpicola. To our knowledge, this is the first study reporting P. trachicarpicola as the pathogens responsible for P. bungeana twig blight in China.

Investigation of the Impact of Land-Use Distribution on PM2.5 in Weifang: Seasonal Variations.

As air pollution becomes highly focused in China, the accurate identification of its influencing factors is critical for achieving effective control and targeted environmental governance. Land-use distribution is one of the key factors affecting air quality, and research on the impact of land-use distribution on air pollution has drawn wide attention. However, considerable studies have mostly used linear regression models, which fail to capture the nonlinear effects of land-use distribution on PM2.5 (fine particulate matter with a diameter less than or equal to 2.5 microns) and to show how impacts on PM2.5 vary with land-use magnitudes. In addition, related studies have generally focused on annual analyses, ignoring the seasonal variability of the impact of land-use distribution on PM2.5, thus leading to possible estimation biases for PM2.5. This study was designed to address these issues and assess the impacts of land-use distribution on PM2.5 in Weifang, China. A machine learning statistical model, the boosted regression tree (BRT), was applied to measure nonlinear effects of land-use distribution on PM2.5, capture how land-use magnitude impacts PM2.5 across different seasons, and explore the policy implications for urban planning. The main conclusions are that the air quality will significantly improve with an increase in grassland and forest area, especially below 8% and 20%, respectively. When the distribution of construction land is greater than around 10%, the PM2.5 pollution can be seriously substantially increased with the increment of their areas. The impact of gardens and farmland presents seasonal characteristics. It is noted that as the weather becomes colder, the inhibitory effect of vegetation distribution on the PM2.5 concentration gradually decreases, while the positive impacts of artificial surface distributions, such as construction land and roads, are aggravated because leaves drop off in autumn (September–November) and winter (December–February). According to the findings of this study, it is recommended that Weifang should strengthen pollution control in winter, for instance, expand the coverage areas of evergreen vegetation like Pinus bungeana Zucc. and Euonymus japonicus Thunb, and increase the width and numbers of branches connecting different main roads. The findings also provide quantitative and optimal land-use planning and strategies to minimize PM2.5 pollution, referring to the status of regional urbanization and greening construction.

Responses of Parameters for Electrical Impedance Spectroscopy and Pressure–Volume Curves to Drought Stress in Pinus bungeana Seedlings

Background and Objectives: Drought occurs more frequently in Northern China with the advent of climate change, which might increase the mortality of tree seedlings after afforestation due to hydraulic failure. Therefore, investigating water relations helps us understand the drought tolerance of tree seedlings. Electrical impedance spectroscopy (EIS) is widely used to assess the responses of plant tissues to stress factors and may potentially reveal the water relations of cells. The aim of this study is to reveal the relationships between EIS and water related parameters, produced by pressure–volume (PV) curves in lacebark pine (Pinus bungeana Zucc.) seedlings reacting to drought stress. Materials and Methods: Four-year-old pot seedlings were divided into three parts (0, 5, and 10 days of drought) before planting, the treated seedlings were then replanted, and finally exposed to post-planting drought treatments with the following soil relative water contents: (i) adequate irrigation (75%–80%), (ii) light drought (55%–60%), (iii) moderate drought (35%–40%), and (iv), severe drought (15%–20%). During the post-planting growth phase, the EIS parameters of needles and shoots, and the parameters of PV curves, were measured coincidently; thus, the correlations between them could be obtained. Results: The extracellular resistance (re) of needles and shoots were substantially reduced after four weeks of severe post-planting drought stress. Meanwhile, the osmotic potential at the turgor-loss point (ψtlp) and the saturation water osmotic potential (ψsat) of shoots decreased after drought stress, indicating an osmotic adjustment in acclimating to drought. The highest correlations were found between the intracellular resistance (ri) of the shoots and ψtlp and ψsat. Conclusions: EIS parameters can be used as a measure of drought tolerance. The change in intracellular resistance is related to the osmotic potential of the cell and cell wall elasticity. Extracellular resistance is a parameter that shows cell membrane damage in response to drought stress in lacebark pine seedlings.

Effect of Temperature, Light, and Storage Time on the Seed Germination of Pinus bungeana Zucc. ex Endl.: The Role of Seed-Covering Layers and Abscisic Acid Changes

Pinus bungeana Zucc. ex Endl. is an endemic conifer tree species in China with high ornamental value. In order to investigate favorable conditions for seed germination and explore the germination inhibition mechanism of this species at high temperatures, the effects of temperature, light, and storage on the mean germination time (MGT), speed of germination (SG), and total germination percentage (TGP) are evaluated here. Seeds that have either been kept still or entered into a state of dormancy at high temperature are assessed here by a recovery experiment. Furthermore, the contribution of covering layers on thermo-inhibition is analyzed here, including the way they work. This has been realized by the structural observation and via the determination of the abscisic acid (ABA) content. The results show that seeds germinate to a high percentage (approximately 90%) at temperatures of 15 or 20 °C, with or without light, whereas higher temperatures of 25 or 30 °C impeded radicle protrusion and resulted in the germination percentage decreasing sharply (within 5%). Inhibition at high temperatures was thoroughly reversed (bringing about approximately 80% germination) by placing the ungerminated seeds in favorable temperatures and incubating them for an additional 30 days. Dry cold storage did little to reduce the temperature request for germination. Embryo coverings, especially the nucellar membrane, and ABA levels both had a dominant role in seed germination regulation in response to temperature. Under favorable temperature conditions, the levels of ABA significantly decreased. Germination occurred when the levels dropped to a threshold of 15 ng/g (FW (Fresh Weight)). Incubation at a high temperature (25 °C) greatly increased ABA levels and caused the inhibition of radicle protrusion.

First Report of Diaporthe eres Causing Twig Dieback of White Bark Pine in China

White bark pine (Pinus bungeana Zucc.) is popularly cultivated as a garden ornamental tree in China because of the high ornamental value. During July 2017, twig dieback symptoms were found on white bark pine trees in the campus of Henan Agricultural University, Zhenzhou, Henan Province, China. The rate of diseased plants was 25% (up to 40% in 2018) in this campus. Early symptoms appeared as round or oval, red-brown lesions on the twigs, which enlarged progressively, leading to dieback. Two representative Diaporthe strains (zm170130 and zm180920) were isolated and purified from two specimens collected in 2017 and 2018 on potato dextrose agar (PDA). Pycnidia scattered in PDA, dark brown to black, globose to subglobose. Conidiogenous cells phialidic, cylindrical, tapering toward the apex, with periclinal thickening. Two kinds of conidia were produced: α-conidia, unicellular, hyaline elliptical or fusiform, two-guttulate, 5.2 to 9.0 × 2 to 3 µm (n = 50); β-conidia hyaline, aseptate, without guttules, filiform, curved, with obtuse ends, 15.5 to 31 × 0.8 to 1.5 µm (n = 50). These morphological characteristics of the isolates agreed with those of Diaporthe eres (Dissanayake et al. 2015; Liu and Tang 1995; Udayanga et al. 2014). The identity of the two fungal isolates was confirmed by DNA sequencing of the ITS rDNA region (GenBank accession nos. MK265702 and MK265701), TUB gene (GenBank accession nos. MK265704 and MK265703), and histone H3 gene (GenBank accession nos. MK265700 and MK265699), which were over 99% homologous to those consensus sequences of the ex-epitype strain D. eres (KJ210529, KJ420799, KJ210550) (Guarnaccia et al. 2018). The pathogenicity of the isolate zm180920 was tested on 2-year-old healthy twigs of white bark pine in July 2018. Five 2-year-old healthy twigs (30 cm long) cut from 5-year-old trees were used for each treatment. Fifteen mycelial plugs harvested from the periphery of a 7-day-old colony were placed on the surface of the wounded twigs, after the twigs had been surface sterilized with 75% ethanol for 2 min; an equal number of noncolonized plugs of PDA served as the control treatment. All test twigs were kept in a clear plastic box with wet sterilized cotton to maintain high relative humidity at 26 to 30°C in the greenhouse. Symptoms similar to those originally observed on the naturally infected twigs were observed 10 days after inoculation, and the same fungus was reisolated from each of the symptomatic twigs; control twigs remained asymptomatic, and no fungus was isolated. The isolates from the symptomatic twigs were identified as D. eres on the basis of the morphology and the same gene sequences. Koch’s postulates were repeated three times with the same results. The fungus has been reported on peach, grapevine, jujube, Red Robin, and so on in China (Dissanayake et al. 2015; Liu and Tang 1995; Song et al. 2019; Yang et al. 2018; Zhang et al. 2018). To our knowledge, this is the first report of D. eres causing twig dieback of white bark pine in China. Disease control strategies in the region are being further studied.

Nucleotide diversity and demographic history of Pinus bungeana, an endangered conifer species endemic in China

AbstractOrographic and climatic oscillations have played crucial roles in shaping the nucleotide diversity and evolutionary history of many species across the Northern Hemisphere. In this study, based on 10 nuclear loci and a chloroplast DNA marker, we analyzed the nucleotide polymorphisms and demographic history of the endangered conifer species Pinus bungeana in Northwest China and investigated the phylogenetic relationships between P. bungeana and two related species, that is, Pinus gerardiana and Pinus squamata. We found that P. bungeana exhibited an extremely low level of nucleotide diversity (πsil = 0.00159). Demographic simulations based on DIYABC analysis showed that P. bungeana underwent demographic expansion and contraction during the Miocene. According to ecological niche modeling, we found that this species survived in situ during the glacial period and was not restricted to southern refugia. We speculate that P. bungeana may have experienced widespread population shrinkage from the Last Interglacial to the Last Glacial Maximum due to geological or climatic events. Isolation‐with‐migration analysis revealed that the divergence (~2.4–4.2 Ma) among P. bungeana and its related species was significantly associated with the Qinghai–Tibetan Plateau uplift events in the mid‐to‐late Tertiary period. Species tree analyses suggested that these three related Pinus species formed a monophyletic clade with high bootstrap support. These results suggest that the Miocene–Pliocene and Pleistocene geological and climatic fluctuations might have profoundly affected the nucleotide diversity and demography of this psychrotolerant conifer species in western China.

Landscape genetics reveals that adaptive genetic divergence in Pinus bungeana (Pinaceae) is driven by environmental variables relating to ecological habitats

BackgroundUnderstanding the genetic basis of local adaptation has long been the concern of biologists. Identifying these adaptive genetic variabilities is crucial not only to improve our knowledge of the genetic mechanism of local adaptation but also to explore the adaptation potential of species.ResultsUsing 10 natural populations and 12 start codon targeted (SCoT) markers, a total of 430 unambiguous loci were yielded. The Bayesian analysis of population structure clearly demonstrated that the 10 populations of P. bungeana could be subdivided into three groups. Redundancy analysis showed that this genetic divergence was caused by divergence selection from environmental variables related to the ecological habitats of “avoidance of flooding” and “avoidance of high temperature and humidity.” LFMM results indicated that Bio1, Bio5, Bio8, Bio12, Bio14, and Bio16, which are related to the ecological habitat of P. bungeana, were correlated with the highest numbers of environment-associated loci (EAL).ConclusionsThe results of EAL characterization in P. bungeana clearly supported the hypothesis that environmental variations related to the ecological habitat of species are the key drivers of species adaptive divergence. Moreover, a method to calculate the species landscape adaptation index and quantify the adaptation potential of species was proposed and verified using ecological niche modeling. This model could estimate climatically suitable areas of species spatial distribution. Taking the results together, this study improves the current understanding on the genetic basis of local adaptation.

Subcellular dissolution of xylan and lignin for enhancing enzymatic hydrolysis of microwave assisted deep eutectic solvent pretreated Pinus bungeana Zucc

The mechanism for enhancing enzymatic hydrolysis during microwave-assisted deep eutectic solvent (Mw-DES) pretreatment in deconstruction of plant cell wall was proposed by combining wet chemical analysis and microscopic measurements. Mw-DES pretreatment achieved significantly higher enzymatic conversion of 81.90% with lower lignin and comparable xylan removal (42.81% and 74.73%, respectively). While DES pretreated sample with higher lignin and xylan removal (66.59% and 74.93%, respectively) obtained limited sugar yield (45.67%). There were no significant differences with respect to chemical structures of lignin fraction between DES and Mw-DES pretreatment but primary discrepancies of topochemical and morphological changes were observed. Non- or low-substituted xylan was directly removed from secondary walls (SW) exposed more cellulose for enzyme attacking after Mw-DES pretreatment. Meanwhile, high-substituted xylan and lignin were synergistically dissolved from cell corner middle lamella (CCML). These topochemical changes of components resulted in cracked and porous cell wall structure, thus facilitating the accessibility of cellulose.