The US National Seed Strategy for Rehabilitation and Restoration: progress and prospects

The National Seed Strategy for Rehabilitation and Restoration was developed by a partnership of 12 federal agencies and over 300 non‐federal cooperators in the United States and launched in 2015. Implementation aims to ensure the availability of genetically appropriate native seed for ecological restoration across the country. Ecological restoration is required in response to a wide range of human impacts. The four main goals of the strategy are: identification of seed needs and availability of genetically appropriate seed; research to improve seed production and ecosystem restoration; development of decision support tools for ecological restoration; and communication and outreach. With the increasing occurrence and intensity of extreme weather events including drought and related wild fires, hurricanes and flooding, native seed is increasingly required in large quantities to build ecological resilience. Acceptance of this need will be crucial to implementation of the National Seed Strategy.     

Genetic and molecular approaches to improve nutritional value of Brassica napus L. seed

Oilseed rape (Brassica napus L.) is a major oil crop that also supplies proteins for the feed industry. In order to reduce total cost production, the objective is to increase oil yield while reducing crop inputs (especially nitrogen and pesticides). Concomitantly, it is necessary to anticipate specific uses (e.g., fatty acid composition) and to ensure the valorisation of the by-products (rapeseed meal). By the past, improvement of seed quality focused on fatty acid balance and low seed glucosinolate content. Current goals include the breeding of yellow-seeded rapeseed lines with high content of seed oil. The use of molecular tools and the exploitation of Arabidopsis knowledge will be presented and discussed.     

Collection and production of native seeds for ecological restoration

The global push to achieve ecosystem restoration targets has resulted in an increased demand for native seeds that current production systems are not able to fulfill. In many countries, seeds used in ecological restoration are often sourced from natural populations. Though providing seed that is reflective of the genetic diversity of a species, wild harvesting often cannot meet the demands for large‐scale restoration and may also result in depletion of native seed resources through over harvesting. To improve seed production and decrease seed costs, seed production systems have been established in several countries to generate native seeds based on agricultural or horticultural production methods or by managing natural populations. However, there is a need to expand these production systems which have a primary focus on herbaceous species to also include slower maturing shrub and tree seed. Here we propose that to reduce the threat of overharvest on the viability of natural populations, seed collection from natural populations should be replaced or supplemented by seed production systems. This overview of seed production systems demonstrates how to maximize production and minimize unintended selection bias so that native seed batches maintain genetic diversity and adaptability to underpin the success of ecological restoration programs.     

Seed planning,sourcing, and procurement

Ensuring the availability of adequate seed supplies of species and sources appropriate for restoration projects and programs necessitates extensive science‐based planning. The selection of target species requires a review of disturbance conditions and reference areas, development of a reference model, and consideration of specific objectives, timeframes, available resources, and budgets as well as the performance of prospective species in past restoration efforts. Identification of seed sources adapted to site conditions is critical to provide for short‐term establishment and long‐term sustainability. Seed zones and plant movement guidelines provide tools for sourcing plant materials with reduced risk of maladaptation. A seed zone framework also facilitates seed use planning and contributes to stability and predictability of the commercial market, thereby reducing costs and improving the availability of adapted seed supplies. Calculating the amount of seed required for each species is based on seed quality (viability, purity), seed weight, expected seedling establishment, and desired composition of the seeding. If adequate collections from wildland stands are not feasible, then seed increase in seed fields or use of nursery stock may be warranted. Adherence to seed collection and seed production protocols for conserving genetic diversity is critical to protect genetic resources and buffer new seedings and plantings against environmental stressors. Maintenance of genetic diversity becomes even more critical considering current or expected climate change impacts. Collaboration and partnerships can benefit seed selection and procurement programs through sharing of information, coordination in project planning, and increasing the availability of native seed.     

Effects of parentage,prior fruit set and pollen load on fruit and seed production in Campanula americana L

Summary We conducted a controlled crossing experiment to examine the effects of maternal and paternal parentage, the size of the pollen load, and prior fruit production on the proportion of flowers that set fruit, seed number per fruit and seed weight in a natural population of Campanula americana. Effects due to the maternal parent were large for all measures of fruit and seed production, while the paternal parent had a significant effect only upon mean seed weight. As the number of prior fruits on the maternal plant increased the probability that a flower would produce a mature fruit, the number of seeds per fruit, and total seed weight per fruit all decreased. We found no effect of the size of the pollen loads used in this study on fruit or seed production. These results are consistent with those of other studies that suggest in natural plant populations maternal effects, especially environmental maternal effects, can have an overwhelming effect on fruit and seed production and on seed characteristics.     

Eco-physiological and Biochemical Responses of Rapeseed (Brassica napus L.) to Abiotic Stresses: Consequences and Mitigation Strategies

Rapeseed yield parameters have been altered due to the increased exposure to abiotic stresses. The changing climatic conditions have reduced biomass production and seed yield, which ultimately affect the success of rapeseed crops. The severity and ability of abiotic stresses to act in tandem are a growing concern for agriculture producers across the globe. Rapeseed is one of the most vital cultivars in the world, serving as a major player in edible oil production. Abiotic stress conditions impose various effects on plant metabolism associated with growth stages, soil water storage capacity and plant physiological aspects. Modern agriculture aims to increased plant productivity to ensure global food security for the future. This can be achieved using quality seed, appropriate agricultural practices, measuring pest reduction techniques and understanding crop production challenges. Important tools, including conventional breeding and biotechnological approaches, can be employed to develop abiotic stress tolerance rapeseed. This review highlights the physiological and biochemical responses of rapeseed to abiotic stresses. The review also addresses conventional and modern stress mitigation strategies for the development of climate-smart rapeseed.

     

Primate Seed Dispersal: Old and New Challenges

Primate seed dispersal plays crucial roles in many ecological processes at various levels of biological organization: from plant population genetics and demography to community assembly and ecosystem function. Although research on primate seed dispersal has advanced significantly in the last 20–30 years, many aspects are still poorly understood. Here, we discuss some new challenges that we need to address, as well as some old ones that still need our attention, highlighting examples from the Neotropics. Despite new analytical tools from network theory, research on primate seed dispersal rarely takes a community-wide approach, thus limiting our understanding of its evolutionary, ecological, and conservation implications. Of particular relevance for conservation are changes caused by landscape-scale processes (e.g., forest loss and fragmentation), but these effects need to be assessed using a landscape approach, which is currently absent in primate seed dispersal research. Agroecosystems can play a key role in maintaining primate seed dispersal in anthropogenic landscapes, but this topic remains poorly studied. Primate seed dispersal research will need to play a role in refaunation projects aimed at restoring plant–animal interactions. Old challenges that we still need to address include the long-term effects of primate declines on plant populations and communities, and the role of primate seed dispersal in the regeneration of degraded habitats. If we take advantage of all tools provided by modern science, from powerful methods of data analyses to molecular techniques, and combine them with strong multidisciplinary collaborations, the future of primate seed dispersal research will indeed be exciting.     

Seed quality and carbon primary metabolism

Improving seed quality is amongst the most important challenges of contemporary agriculture. In fact, using plant varieties with better germination rates that are more tolerant to stress during seedling establishment may improve crop yield considerably. Therefore, intense efforts are currently being devoted to improve seed quality in many species, mostly using genomics tools. However, despite its considerable importance during seed imbibition and germination processes, primary carbon metabolism in seeds is less studied. Our knowledge of the physiology of seed respiration and energy generation and the impact of these processes on seed performance have made limited progress over the past three decades. In particular, (isotope‐assisted) metabolomics of seeds has only been assessed occasionally, and there is limited information on possible quantitative relationships between metabolic fluxes and seed quality. Here, we review the recent literature and provide an overview of potential links between metabolic efficiency, metabolic biomarkers, and seed quality and discuss implications for future research, including a climate change context.     

Direct and indirect effects of masting on rodent populations and tree seed survival

Many plant species are thought to benefit from mast seeding as a result of increased seed survival through predator satiation. However, in communities with many different masting species, lack of synchrony in seed production among species may decrease seed survival by maintaining seed predator populations through the intermast cycle. Similarly, masting by different plant species may have different effects on the seed predator community. We conducted a three-year study in a northeastern USA temperate deciduous forest to determine if production of large seed crops by several tree species was synchronous, and if they had similar effects on all small mammal species. We found that red oak mast crops resulted in increased densities of Peromyscus leucopus and P. maniculatus , but had no effect on Clethrionomys gapperi abundance. Conversely, C. gapperi populations, but not Peromyscus populations, appeared to increase in response to a large red maple seed crop. Differences in small mammal abundance resulted in changes in species-specific seed survival: in the year of abundant C. gapperi , experimentally placed red oak acorns had significantly higher survival than in the year of high Peromyscus abundance. Red oak acorn removal was positively correlated with Peromyscus abundance, while red maple seed removal was significantly higher with increased C. gapperi abundance. Thus, species-specific seed production had differential effects on subsequent small mammal abundance, which in turn affected seed survival. We suggest that at the level of the community, even short-term lack of synchrony in production of large seed crops can cause variation in postdispersal seed survival, through differential effects on the community of small mammal seed predators.     

Pollination biology and the impact of floral display, pollen donors, and distyly on seed production in Arcytophyllum lavarum (Rubiaceae)

In animal-pollinated plants, two factors affecting pollen flow and seed production are changes in floral display and the availability of compatible mates. Changes in floral display may affect the number of pollinator visits and the availability of compatible mates will affect the probability of legitimate pollination and seed production. Distyly is a floral polymorphism where long-styled (pin) and short-styled (thrum) floral morphs occur among different individuals. Distylous plants frequently exhibit self and intra-morph incompatibility. Therefore changes in morph abundance directly affect the arrival of compatible pollen to the stigmas. Floral morph by itself may also affect female reproductive success because floral morphs may display differences in seed production. We explored the effects of floral display, availability of neighboring compatible mates, and floral morph on seed production in the distylous herb ARCYTOPHYLLUM LAVARUM. We found that floral display does not affect the mean number of seeds produced per flower. There is also no effect of the proportion of neighboring legitimate pollen donors on seed production in pin or thrum flowers. However, floral morphs differed in their female reproductive success and the thrum morph produced more seeds. Hand pollination experiments suggest that differences in seed production between morphs are the result of pollen limitation. Future research will elucidate if the higher seed production in thrum flowers is a consequence of higher availability of pollen donors in the population, or higher efficiency of the pin morph as pollen donor.     

野慈姑(Sagittaria trifolia)人工授粉的有效性:授粉工具与花粉保存

人工授粉作为一项关键性技术在生态研究与农业生产领域广泛应用,但是授粉过程中的工具有效性以及花粉保存尚未受到研究者的关注。以植物野慈姑为试验材料,研究了人工授粉方式和花粉保存条件对繁殖的影响。两年的结果表明,相较于直接接触式授粉,借助毛刷工具授粉显著降低了野慈姑的座果概率和种子数。花粉经过半小时野外高温保存后,其授粉的座果概率显著高于对照组,但单果种子数和种子大小保持稳定。综上,在野慈姑的人工授粉中应避免使用毛刷等工具,离体花粉可置于野外环境适当保存。在相关应用中,研究人员应当警惕工具授粉造成的负面影响,注意比较工具与其他授粉方式的等效性,保证实验的科学性。     

Responses of a specialist and a generalist seed predator to variation in their common resource

Fluctuations of resources in time and space will influence not only species abundance but also interactions among species. For plant–consumer interactions, the effects of resource variation have mostly been studied in systems with high resource variability. Systems with moderate variations are less studied, although ecological and evolutionary dynamics of plants and consumers are likely to be affected also by less extreme variability. The effects of variation in a particular resource should depend on consumer diet width.
We examined how spatial and temporal variation in seed production in the perennial herb Lathyrus vernus influenced population dynamics and resource utilization in two beetle pre-dispersal seed predators with different host ranges over six years. The monophagous Apion opeticum occupied fewer patches and had lower densities than the oligophagous Bruchus atomarius . The proportion of seeds attacked increased with increases in seed production between years for both seed predators. A possible explanation for these patterns is that population dynamics of beetles are driven largely by local factors and that the same factors influence both beetle performance and seed production. In B. atomarius , patterns may also be influenced by a more pronounced preference for L. vernus in years with a high seed production in L. vernus . We conclude that relatively modest variation in seed production may result in responses that differ in both direction and extent from those usually observed in systems with high variation in seed production.     

Dust seed production and dispersal in Swedish Pyroleae species

Dust seeds are the smallest seeds in angiosperms weighing just about a few micrograms. These seeds are characteristic of most orchids, and several studies have been performed on seed features, fecundity and dispersal of orchid dust seeds. In this study we examine seed features, seed production and seed dispersal in another plant group with dust seeds, the Pyroleae (Monotropoideae, Ericaceae), focusing on six species: Pyrola chlorantha, P. minor, P. rotundifolia, Chimaphila umbellata, Moneses uniflora and Orthilia secunda. Seed production per capsule among these species was in the range between ca 1000 and 7800, and seed production per capsule bearing shoot was in the range between ca 7000 and 60 000. Combining our results with published information on pollen‐ovule ratios suggests that these Pyroleae species have a generally efficient pollination system. The most fecund species was P. minor, the only species among the investigated that is probably largely self‐pollinating. The investigated Pyroleae species have a seed production comparable to the less fecund orchid species. We studied seed dispersal in the field in one of the species, P. chlorantha. Despite the extremely small and potentially buoyant seeds, the vast majority of seeds are deposited close to the seed source, within a few meters. Further studies on the recruitment ecology of the investigated Pyroleae species are currently under way.     

Grass seed production in the central Monte desert during successive wet and dry years

In desert regions, water availability triggers primary production, which determines seed production, the composition and size of soil seed reserves and the abundance and behaviour of seed-eating animals. In the central Monte desert, large precipitation events (≥10 mm) account for a high proportion of growing season’s rainfall. Our first objective here was to assess whether and how timing and amount of seed production of C₃ and C₄ perennial grasses are linked to spring and summer precipitation pulses and to estimate the seasonal and year-to-year variability in seed production. Our second aim was to calculate grass seed production and compare it with seed requirements by granivorous animals to infer whether the animals can exert top-down effects on plant populations. Seed production of C₃ and C₄ species was triggered by significant spring and summer rainfall, respectively. Such distinct response may be associated with the effect of precipitation during flower development and seed set in both functional groups. In all species, seed production varied among years. Rainfall pulses in the summer triggered and positively affected the magnitude of seed production in most C₄ grasses. However, all perennial grasses were able to produce high amount of seeds even during a year subjected to extreme drought, suggesting that perenniality would allow these species to make large reproductive investment despite harsh environmental conditions. The comparative assessment of seed production and consumer demands suggests that it is unlikely that granivory exerts a top−down control on grasses in the Monte desert.     

Seed coating with beneficial microorganisms for precision agriculture

Seed coating is a technique of covering seeds with adhesive agents to improve seed performance and plant establishment while reducing production cost. To meet the needs of development of precision agriculture, seed coating has been widely used in agriculture as an effective means to alleviate biotic and abiotic stresses, thus enhancing crop growth, yield, and health. Plant growth promoting microorganisms (PGPM) are recognized as essential contributors to improving agricultural productivity via direct application to the rhizosphere and plant tissues, or seed inoculation. However, during conventional inoculation processes, several factors such as insufficient microbial survival, hindrance in the application of biocontrol inocula to the seeds and exposure to unsuitable temperature and light in subsequent seed storage, force us to explore efficient and reliable microbial application tools. Recently, biological seed coating with PGPM is proposed as an alternative to conventional seed treatment (such as fertilizer and protection products) due to its ecological safety and socio-economic aspects. In this review, microbial seed coating technology and its contribution to sustainable precision agriculture are well discussed and highlighted in the extensive table and elaborate schematic drawings.     

Factors regulating fruit and seed production in the desert annual Lesquerella gordonii

Summary This study examines the pattern of reproduction and factors that limit the maternal reproductive output in the self-incompatible annual, Lesquerella gordonii. Greenhouse experiments showed that fruits do not abscise and they mature if they contain at least one fertilized (outcrossed) ovule. Field studies showed that flowering increased to a peak and then fell off rapidly, while seed production/fruit decreased through the season. Pollen addition did not increase the number of fruit or seeds per fruit, suggesting that fruit and seed production are not pollinator limited. Addition of water increased fruit and seed production by extending the life of the plant, by increasing the number of stalks which flowered, and by increasing the number of seeds per fruit. This indicates that fruit and seed production are resource limited. Fruits are relatively inexpensive as compared to seeds as over 93% of the water in fruits is contained in the seeds. Fifty-three percent of the plants were lost to herbivory as were 64.6% of the fruits on the remaining plants, indicating that herbivory also limited fruit and seed production. It is hypothesized that high fruit set coupled with variable seed set in L. gordonii is an adaptive response to unpredictable, variable resource levels, and high herbivory risk.     

Soybeans as bioreactors for biopharmaceuticals and industrial proteins

Plants present various advantages for the production of biomolecules, including low risk of contamination with prions, viruses and other pathogens, scalability, low production costs, and available agronomical systems. Plants are also versatile vehicles for the production of recombinant molecules because they allow protein expression in various organs, such as tubers and seeds, which naturally accumulate large amounts of protein. Among crop plants, soybean is an excellent protein producer. Soybean plants are also a good source of abundant and cheap biomass and can be cultivated under controlled greenhouse conditions. Under containment, the plant cycle can be manipulated and the final seed yield can be maximized for large-scale protein production within a small and controlled area. Exploitation of specific regulatory sequences capable of directing and accumulating recombinant proteins in protein storage vacuoles in soybean seeds, associated with recently developed biological research tools and purification systems, has great potential to accelerate preliminary characterization of plant-derived biopharmaceuticals and industrial macromolecules. This is an important step in the development of genetically engineered products that are inexpensive and safe for medicinal, food and other uses.     

Seed production in fens and fen meadows along a disturbance gradient

Question: The seed production in several wetland communities across Europe was investigated and differences in seed output in relation to disturbance intensity were tested. The relationship between the vegetation composition and the seed production profile was examined and the results are discussed in relation to restoration. Location: Poland, Germany and the Netherlands. Methods: The seed production in various plant communities was estimated, based on field counts. In addition, records from available databases were used for missing data. Multivariate methods were used to characterize the vegetation and seed production. Communities were grouped according to level of disturbance and tested for differences in seed production. Similarity between vegetation composition and seed profile was examined using the Sørensen index and Spearman correlation coefficient. Results: It was found that the seed production of the studied communities is large, variable and in general increasing with disturbance intensity. The estimated median seed production was ca. 24 × 10³ seeds m^?2 in fens, 167 × 10³ in fen meadows and 556 × 10³ seeds m^?2 in degraded meadows. The majority of seeds was produced by just a few species. The similarity between the vegetation composition and the seed production profile was low (similarity 52%, correlation coefficient 0.42, P<0.05) and slightly increased with disturbance intensity. Conclusions: Increased disturbance enhances seed production at the community level. The composition of the vegetation is a poor predictor of the seed output. It is estimated that the number of seeds transferred with hay is much lower than the seed production in fens and fen meadows.     

Effects of the Neotyphodium endophyte fungus on dormancy and germination rate of Lolium multiflorum seeds

Abstract Neotyphodium frequently occurs as an endophyte in grasses. Evidence shows enhanced fitness of endophyte infected grasses relative to non‐infected ones. Some studies of seed germination show endophyte enhancement of plant fitness in various environments, but inconsistent results indicate that further studies are needed. So far, experiments have failed to separate the confounded effects of population origin and seed management. For this reason, we evaluated the effects of endophyte infection on seed dormancy and germination in Lolium multiflorum using an experimental design controlling these factors. Depending on the year of seed production, endophyte infection modified seed response to light quality, affecting predominantly seed dormancy levels. Nevertheless, the endophyte did not affect base temperature or thermal time of germination. We concluded that endophytes were not a strong influence on germination behaviour. We speculate from our results that the presence of the endophyte changes germination by an indirect effect, in extending growth of the maternal plant during seed development and ripening. The direct effect of hyphae in the seed on seed behaviour was disregarded, because the difference between infected and non‐infected seed varied within the year of seed production. Future experiments should focus on effects of the endophyte on the canopy of parent plants during seed production and ripening, and, hence, on subsequent dormancy and germination of the seeds.     

Evaluation of pollinator effectiveness based on pollen deposition and seed production in a gynodieocious alpine plant,Cyananthus delavayi

Examining variations in pollinator effectiveness can enhance our understanding of how pollinators and plants interact. Pollen deposition and seed production after a single visit by a pollinator are often used to estimate pollinator effectiveness. However, seed production is not always directly related to pollen deposition because not all pollen grains that are deposited on a stigma are compatible or conspecific. In the field, we tested pollinator effectiveness based on pollen deposition and the resulting seed production after single visits by different pollinator groups in a gynodieocious alpine plant Cyananthus delavayi (Campanulaceae). Our results showed that mean pollen deposition was generally inconsistent with mean seed production when comparisons were performed among different pollinator groups and sexes. In general, the correlations were not significant between pollen deposition and seed production in both perfect and female flowers after single visits by halictid bees, bumble bees, and hoverflies. We suggest seed set of virgin flowers after single visits is a more reliable indicator of pollinator effectiveness than pollen deposition and would be a better indicator of pollinator effectiveness for future studies.