Search Results (41)

Plantations of the valuable Chinese timber species, Chamaecyparis hodginsii, established by planting, primarily rely on seed orchards for propagation. Therefore, effective management of the genetic composition of these orchards is essential to ensure a sustainable supply of high-quality seeds. However, the mating system and pollen dispersal mechanisms in its high-generation seed orchards remain unclear, limiting precise genetic management. To address this, we analyzed 30 parental clones and 75 of their open-pollinated progeny from a second-generation seed orchard using 15 polymorphic EST-SSR markers. Compared to reported natural populations of C. hodginsii, both parental and progeny populations maintained high genetic diversity (mean uHe = 0.438 and 0.449, respectively), with a significant excess of heterozygotes (mean Fis = −0.084 and −0.066, respectively). Population genetic structure analysis indicated weak genetic differentiation among the parental genetic groups (mean Fst = 0.012), which was further reduced in the progeny population (mean Fst = 0.003) due to open pollination, reflecting a trend toward genetic homogenization. The mating system was characterized exclusively by outcrossing (tm = 1.000). However, paternity analysis revealed highly skewed paternal contributions, a low effective number of pollen donors (Nep = 8.13), and contributions of S5, S11, and S17 as dominant pollen parents, with 17.33% external pollen flow. These findings elucidate the mechanisms underlying sustained genetic diversity despite unequal paternal contributions and provide a theoretical basis for optimizing parental configuration and pollen management. Full article

Ambrosia artemisiifolia (ragweed) is a highly invasive species that produces large amounts of allergenic pollen. This poses a serious health risk to allergy sufferers. The “Ragweed Finder” is an Austrian citizen science platform (website and app) that enables the public to report occurrences of ragweed, which are then verified by experts. Over 90% of reports are confirmed as positive, with most originating from eastern Austria, where ragweed is widespread. The number of reports has generally increased over time, except in 2020 during the pandemic. Report frequency does not directly correlate with daily pollen concentrations, but peaks before and during pollen season. Most observations occur along traffic routes, likely due to seed dispersal by vehicle airflow or easier accessibility for users. Verified observations are displayed on an interactive map, helping allergy sufferers to avoid exposure and informing local authorities of the need for targeted control actions. The data are also used to raise awareness among policymakers and help to enact the first law for the control and prevention of ragweed in Burgenland (Austria), in 2021: the “Burgenland Ragweed Control Act”. This demonstrates the success of the “Ragweed Finder” as an important tool for monitoring this invasive species in Austria. Full article

Many plant species depend on pollen flow to maximize reproduction and maintain genetic variability. Pollinators mediate this process, but distance between individuals can influence its benefits. Proximity may cause inbreeding depression, while extreme distances can mix locally adapted genotypes, leading to outbreeding depression and reduced fitness. Vereda palm swamps, shaped by the water table, are important habitats in the Cerrado, but they face anthropogenic changes that can affect reproduction, pollinators, and genetic diversity. This study examined how pollen dispersal distance influences the reproductive success of spiral ginger (Costus spiralis, Costaceae), a vereda self-compatible rhizomatous herb pollinated by hummingbirds. Hand pollinations were carried out between plants ranging from 10 to 2000 m distant, and the resulting fruit-set and seed quality traits were evaluated. Fruit set did not vary significantly with distance, with no hint of either inbreeding or outbreeding depression. Nevertheless, seeds resulting from shorter pollination distance (10 m) were heavier, while germination rates were up to five-fold higher at greater pollination distances than at shorter pollination distances. These distinct seed traits are possibly related to main hummingbird pollinators of C. spiralis, which show distinct foraging strategies. The results suggest that C. spiralis is adapted to various modes of pollen dispersal, ensuring reproduction via either territorial or traplining hummingbirds. Full article

Cannabis is usually dioecious, with male and female flowers on separate plants. Cultivators prioritize the use of female plants because their flowers contain a higher density of glandular trichomes, the primary source of cannabinoids, compared to male flowers. Feminized seeds, which give rise exclusively to female plants, are highly valued in the cannabis industry. These seeds are produced by crossing a natural female plant with another female plant that has been masculinized to generate pollen. Masculinization is achieved by inhibiting ethylene and/or applying gibberellins prior to flower initiation in female plants. Currently, silver thiosulfate (STS) is the most common treatment used in the cannabis industry, though environmental concerns arise from silver applications. This study compared STS with three other ethylene-inhibiting agents: aminoethoxyvinylglycine (AVG), cobalt nitrate (CBN), and 1-methylcyclopropene (1-MCP). Some STS and CBN treatments also included gibberellic acid as a synergist. STS-treated plants displayed the most effective masculinization and pollen dispersal, compared to plants treated with AVG. Only STS and AVG generated sufficient pollen for collection. This pollen was initially tested for germination potential and subsequently stored for up to five weeks at 22.2 °C, 7.2 °C, or 1.1 °C.Germination rates ranged from 2.2% to 5.8%, underscoring the influence of storage conditions and highlighting the need to refine preservation methods to enhance agricultural viability. Pollen from plants treated with AVG remained viable for three weeks at 1.1 °C, although there were concerns about a high risk of phytotoxicity. STS-treated pollen also remained viable for three weeks at the same temperature. Neither CBN nor 1-MCP treatments were effective in inducing masculinization. No clear synergistic effect of gibberellic acid combined with STS or AVG was observed; however, growth stunting led to increased mortality. Due to pollen viability and phytotoxicity problems with AVG, STS remains the best treatment to masculinize female cannabis plants when breeding for feminized seeds. Full article

The gene flow rate in rice (Oryza sativa L.) is a critical factor for establishing safe isolation distances between genetically modified (GM) and non-GM varieties and for ensuring varietal purity in rice breeding programs. This study refines existing gene flow models by disentangling two key components of rice pollen dynamics: quantitative pollen competition and genetic competitiveness. We define B as the proportion of GM pollen within mixed pollen, representing quantitative pollen competitiveness. The outcrossing parameter C_b reflects the likelihood of successful fertilization and seed development by foreign pollen, while the hybrid compatibility parameter C_p captures the relative fertilization success of GM versus non-GM pollen within the same pollen pool. Together, C_b and C_p characterize the genetic competitiveness of rice pollen. Our findings reveal a nonlinear relationship between B and the observed GM pollen rate G, which may exhibit either upward or downward curvature. A nonlinear model provides a significantly better fit to this relationship than a linear model, improving R² by 4.1–21.4% and reducing RMSE by 9.9–47.8%. The parameters C_b and C_p play central roles in determining gene flow; higher values correspond to stronger GM pollen competitiveness, resulting in higher gene flow rates and greater dispersal distances. Specifically, C_b sets the range of the B–G curve, while C_p determines its curvature. Full article

Wildfires have had measurable impacts on pollen dispersal in some areas; both facilitation and potential barriers to pollen movement have been reported. These dispersal dynamics in turn affect population genetics and reestablishment of seed-producing plants, at times significantly impacting the successional trajectory of the area in question. However, research on post-fire pollen distribution and occurrence is lacking for the boreal and sub-boreal forests of western Canada, and many communities that have been heavily impacted by wildfire remain concerned about the future forest landscape of these areas. We analyzed post-fire pollen samples from unburned and severely burned sub-boreal spruce stands in north-central British Columbia four years after a major wildfire. We used pollen traps to measure the occurrence and abundance of pollen types from four important plant families: Asteraceae, Ericaceae, Onagraceae, and Pinaceae families, to address specific concerns of the First Nation communities with territories overlapping the Shovel Lake wildfire burned area. Pinaceae pollen was found across all traps and was observed as the most dominant pollen type at all study sites, while pollen belonging to other families was found less frequently. No significant differences in pollen occurrence or abundance were found between burn severities, despite differences in the plant communities; however, plant and pollen abundance were found to be positively correlated to one another. These results may indicate that, as previously noted in other conifer-dominated forests, openings of the forest landscape by wildfire may facilitate rather than hinder pollen movements. Understory species should be studied in more detail as the effect of wildfire on pollen transport may vary between taxa and pollination syndromes. Full article

Himantoglossum metlesicsianum is a threatened orchid with low population numbers and fragmented distribution, present in four of the Canary Islands. This study focused on assessing the genetic variability and population genetic structure of the natural populations known to date, identifying those characteristics of the species that condition the flow and genetic variation. For that purpose, we collected samples from eight sites in its distribution range and developed 14 polymorphic microsatellite markers. Despite its rarity, this orchid presents high levels of genetic diversity and a homogeneous population structure, characterised by a low degree of genetic differentiation and patterns consistent with high genetic connectivity among populations. Our results suggest that the species might show dichotomy in seed dispersal, combining long- and short-distance events. In addition, it is possible that pollen cross-pollination (pollinia) between adjacent sites may also be involved. In conclusion, these findings reveal unexpectedly high genetic diversity and connectivity among populations, despite the species’ rarity and fragmented distribution, highlighting key biological traits that should be considered in future conservation and recovery plans. Full article

To address challenges in hybrid rice seed production—specifically labor dependence, low uniformity of pollen distribution, and low operational efficiency—which collectively drive up large-scale production costs, technological innovations are critical. However, despite the demonstrated potential of UAV-assisted pollination, the quantitative relationships between its operational parameters (altitude, speed, flight patterns) and pollen dispersal dynamics remain poorly understood, impeding standardization efforts. In this study, guided by agronomic pollination requirements, we developed an integrated analytical framework linking “pollen density-yield” dynamics to elucidate the governing mechanisms of flight parameters on pollination quality. A DJI T50 UAV was used to carry out the assisted pollination test on two varieties of hybrid rice, Changtian You 405 and Wanxiang You 377, to explore the effects of different flight speeds, altitudes, and trajectories of the UAV on pollination quality and to evaluate the cost-effectiveness ratio, taking the yield and its composition as the evaluation indexes. The experimental results showed that the UAV flight operation parameters had a significant effect on the pollination quality, and the best pollination quality was obtained when the flight altitude was 4 m and the speed was 3 m/s, achieving yields of 2.64 and 3.15 t/hm²; the average yields of the UAV-assisted pollination were 2.10 and 2.61 t/hm², and the filled grain percentages were 15.76% and 34.2%, respectively. These increased the yields by 21.4% and 11.06%, respectively, and the filled grain percentages by 8.69% and 3.95%, compared with artificial pollination. The results also showed that the cost-effectiveness ratio of UAV-assisted pollination was 28.11% lower than that of artificial operation. The results indicate that UAVs have great application prospects in hybrid rice pollination. Full article

Tamarix chinensis Lour. is a halophytic shrub native to coastal China, commonly used in afforestation and ecological restoration due to its high tolerance to salinity and drought. To understand how this species maintains genetic variation and adapts to extreme environments, we examined the genetic diversity, mating system, and spatial genetic structure of a natural T. chinensis population on the geographically isolated and environmentally harsh Wudi Seashell Island. Using both SSR and ISSR markers, we observed high levels of genetic diversity despite the small population size and spatial fragmentation. SSR markers revealed an average of 11.75 alleles per locus, with an expected heterozygosity (He) of 0.754 and an observed heterozygosity (Ho) of 0.702. ISSR markers showed a polymorphic locus rate of 97.87%, with a mean He of 0.402. Parentage analysis revealed relatively long seed and pollen dispersal distances, with most dispersal occurring within 150 m and seeds and pollens occasionally reaching 948 m and 447 m, respectively. The species exhibited a mixed mating system, with a multilocus outcrossing rate of 0.554, contributing to gene flow and reducing inbreeding. A fine-scale spatial genetic structure was detected within 75 m, consistent across both SSR and ISSR markers, suggesting limited local gene dispersal. These findings provide new insights into the adaptive strategies of T. chinensis in marginal habitats and offer valuable guidance for conservation and restoration efforts in vulnerable coastal ecosystems. Full article

The repeated application of herbicides has led to the development of herbicide resistance. Models are useful for identifying key processes and understanding the evolution of resistance. This study developed a spatially explicit model at a landscape scale to examine the dynamics of Lolium rigidum populations in dryland cereal crops and the evolution of herbicide resistance under various management strategies. Resistance evolved rapidly under repeated herbicide use, driven by weed fecundity and herbicide efficacy. Although fitness costs associated with resistant plants reduced the resistance evolution, they did not affect the speed of its spread. The most effective strategies for slow resistance involved diversifying cropping sequences and herbicide applications. Pollen flow was the main dispersal vector, with seed dispersal also making a significant contribution. Strategies limiting seed dispersal effectively decreased resistance spread. However, the use of a seed-catching device at harvest could unintentionally enrich resistance in the area. It would be beneficial to optimize the movement of harvesters between fields. The model presented here is a useful tool that could assist in the exploration of novel management strategies within the context of site-specific weed management at landscape scale as well as in the advancement of our understanding of resistance dynamics. Full article

Exploring the gene flow and its causes in complex habitats of forest trees is valuable for understanding species’ adaptive evolution. Pinus yunnanensis var. tenuifolia (PYT) is mainly distributed in the dry–hot valleys along the Nanpan-Hongshui rivers in southwest China, an ecologically fragile area. In this study, we analyzed 1056 seeds from eleven natural populations of PYT across its range using twelve cpSSR markers to explore haplotype polymorphisms and correlations with environmental factors. The results revealed a high genetic diversity (H_E = 0.83), with the private haplotypes significantly exceeding the shared haplotypes. A genealogical structure was observed among the populations, with a moderate differentiation (F_ST = 0.162). The population clustering and haplotype network demonstrated localized areas of pollen exchange, especially in the middle and lower reaches of the river. Redundancy analysis showed that, as the populations were closer to the river, genetic diversity tended to decrease significantly, implying that the pollen dispersal is restricted by the foehn effect in the valley. Variability in genetic differentiation among the offspring populations was primarily influenced by geographic factors, such as mountains and rivers, which, along with local environmental adaptations, shaped the pollen distribution pattern. These findings may facilitate the sustainable management and conservation of PYT and other species under similar habitats. Full article

Genetic diversity is crucial for determining the evolutionary potential of a species and is essential for developing optimal conservation strategies. The impact of habitat fragmentation on the genetic diversity of food-deceptive orchids seems to be unpredictable because of their specialized seed and pollen dispersal mechanisms. The habitat of deceptive Cypripedium flavum was severely fragmented during the past half century. This study investigated the genetic diversity and structure of seven fragmented Cypripedium flavum populations in Shangrila County using AFLP markers. A total of 376 alleles were identified, with a range of 70 to 81 alleles per locus. The species exhibited considerable genetic diversity, as evidenced by an average Nei’s gene diversity (H) of 0.339 and a Shannon’s information index (I) of 0.505, with all loci being polymorphic. Based on Molecular Variance (AMOVA), 8.75% of the genetic differentiation was found among populations, while the remaining 91.25% of genetic variation occurred within populations. Population structure analysis revealed that the C. flavum germplasm can be categorized into 2 distinct groups, among which there was significant gene flow. Despite habitat fragmentation, C. flavum still retained a high level of genetic diversity, and the substantial gene flow (5.0826) is a key factor in maintaining the genetic diversity. These findings offer valuable insights for the conservation and potential use of C. flavum genetic resources. Full article

Meconopsis integrifolia is an endangered Tibetan medicinal plant with significant medicinal and ornamental value. Understanding its genetic diversity and structure is crucial for its sustainable utilization and effective conservation. Here, we develop a set of SSR markers based on transcriptome data to analyze the genetic diversity and structure of 185 individuals from 16 populations of M. integrifolia. The results indicate that M. integrifolia exhibits relatively high genetic diversity at the species level (the percentage of polymorphic bands PPB = 91.67%, Nei’s genetic diversity index He = 0.2989, Shannon’s information index I = 0.4514) but limited genetic variation within populations (PPB = 12.08%, He = 0.0399, I = 0.0610). The genetic differentiation among populations is relatively high (the coefficient of gene differentiation GST = 0.6902), and AMOVA analysis indicates that 63.39% of the total variation occurs among populations. This suggests that maintaining a limited number of populations is insufficient to preserve the overall diversity of M. integrifolia. Different populations are categorized into four representative subclusters, but they do not cluster strictly according to geographical distribution. Limited gene flow (Nm = 0.2244) is likely the main reason for the high differentiation among these populations. Limited seed and pollen dispersal abilities, along with habitat fragmentation, may explain the restricted gene flow among populations, highlighting the necessity of conserving as many populations in the wild as possible. Full article

The conservation biology field underscores the importance of understanding genetic diversity and gene flow within plant populations and the factors that influence them. This study employs Simple Sequence Repeat (SSR) molecular markers to investigate the genetic diversity of the endangered plant species Saussurea involucrata, offering a theoretical foundation for its conservation efforts. Utilizing sequencing results to screen SSR loci, we designed and scrutinized 18 polymorphic microsatellite primers across 112 samples from 11 populations in the Bayinbuluke region. Our findings reveal high genetic diversity (I = 0.837, He = 0.470) and substantial gene flow (Nm = 1.390) among S. involucrata populations (China, Xinjiang), potentially attributed to efficient pollen and seed dispersal mechanisms. Principal Coordinate Analysis (PCoA) indicates a lack of distinct genetic structuring within the Bayinbuluke populations. The cluster analysis using STRUCTURE reflected the genetic structure of S. involucrata to a certain extent compared with PCoA. The results showed that all samples were divided into four groups. To safeguard this species, we advocate for the in situ conservation of all S. involucrata populations in the area. The SSR markers developed in this study provide a valuable resource for future genetic research on S. involucrata. Full article

Wildfires act as a selection force threatening the sustainability and diversity of forest genetic resources. Few studies have investigated the genetic effects of forest wildfires. Species with perennial canopy seed banks in serotinous cones and soil or with long-distance seed and pollen dispersion can preserve genetic diversity and population differentiation under normal fire regimes. To test this hypothesis, we characterised molecularly Pinus pinaster Aiton (maritime pine) seedlings produced from seeds sampled in post-fire, naturally regenerated populations that had been subject to different fire regimes in the North of Portugal using inter-simple sequence repeats (ISSRs). The sampled populations burned once (A), twice (B), or three (D) times or had no prior fire history (C, control). Given the globally low seed germination ability, only 104 plantlets regenerated and were described. These plantlets were grouped according to their origin population. Intra-group ISSR polymorphism ranged from 72.73% (B) to 89.41% (D), revealing genetic differentiation among groups originating from populations that had experienced different fire recurrence. Overall, the unaffected genetic diversity of the regenerated plantlets allowed us to accept the hypothesis. Our findings enhance our understanding of the species ability to withstand fire-induced challenges and their responses to wildfires, guiding conservation endeavours and forest management strategies to bolster ecosystem resilience. Full article