Small Seeds Research Articles

Seed Size, Not Dispersal Syndrome, Determines Potential for Spread of Ricefield Weeds by Gulls.

Recent field data suggest that migratory gulls disperse many rice field weeds by gut passage (endozoochory), most of which are dry fruited and widely assumed to have no long-distance dispersal mechanisms, except via human activity. We investigated this mechanism with a feeding experiment, in which seeds of five common rice field weeds (in order of increasing seed size: Juncus bufonius, Cyperus difformis, Polypogon monspeliensis, Amaranthus retroflexus, and the fleshy-fruited Solanum nigrum) were fed to seven individuals of lesser black-backed gulls Larus fuscus held in captivity. We quantified seed survival after collecting faeces at intervals for 33 h after ingestion, then extracting intact seeds and running germination tests, which were also conducted for control seeds. All five species showed high seed survival after gut passage, of >70%. Gut retention times averaged 2-4 h, but maxima exceeded 23 h for all species. Germinability after gut passage was 16-54%, and gut passage accelerated germination in J. bufonius and S. nigrum, but slowed it down in the other species. All species had lower germinability after gut passage compared to control seeds (likely due to stratification prior to the experiment), but the loss of germinability was higher in smaller seeds. There was no evidence that the different dispersal syndromes assigned to the five species (endozoochory, epizoochory or barochory) had any influence on our results. In contrast, mean gut retention time was strongly and positively related to seed size, likely because small seeds pass more quickly from the gizzard into the intestines. Non-classical endozoochory of dry-fruited seeds by waterbirds is a major but overlooked mechanism for potential long-distance dispersal, and more research into this process is likely essential for effective weed management.

Reframing the question of Baytown food production: plant remains from the Oliver site, northern Yazoo Basin, Mississippi

ABSTRACT Site densities in Mississippi's Upper Yazoo Basin indicate that populations increased in numbers during the Late Woodland period. Plant remains recovered during salvage operations at the Oliver site in Coahoma County contribute to a database confirming the importance of both wild and cultivated resources for Baytown people of that time. Because the samples reported here were retrieved by water screening rather than flotation, small seeds are uncommon. Still, all four starchy seed taxa and both oily seed crops belonging to the Eastern Agricultural Complex were recovered, along with the unidentified grass known as Type X. The abundance of acorn shell at Oliver and nearby sites with Baytown components calls for more inquiry into how acorns were accessed, processed, cooked, and eaten. We call attention to the pottery that occurs in high frequencies, suggesting that much of it was used to store, cook, and leach tannins from acorns, as well as to prepare other foodstuffs. Discussions of early agriculture in the Yazoo Basin once focused on corn, subsequently incorporating pre-corn native crops. We propose an expanded concept of food production that includes management of nut tree groves and tending of gardens to partially explain the thickly populated Late Woodland Delta landscape.

Linking seed size and number to trait syndromes in trees

AbstractAimOur understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whether reproduction represents an independent dimension related to a seed size–seed number trade‐off.LocationMost of the data come from Europe, North and Central America and East Asia. A minority of the data come from South America, Africa and Australia.Time period1960–2022.Major taxa studiedTrees.MethodsWe gathered 12 million observations of the number of seeds produced in 784 tree species. We estimated the number of seeds produced by individual trees and scaled it up to the species level. Next, we used principal components analysis and generalized joint attribute modelling (GJAM) to map seed number and size on the tree traits spectrum.ResultsIncorporating seed size and number into trait analysis while controlling for environment and phylogeny with GJAM exposes relationships in trees that might otherwise remain hidden. Production of the large total biomass of seeds [product of seed number and seed size; hereafter, species seed productivity (SSP)] is associated with high leaf area, low foliar nitrogen, low specific leaf area (SLA) and dense wood. Production of high seed numbers is associated with small seeds produced by nutrient‐demanding species with softwood, small leaves and high SLA. Trait covariation is consistent with opposing strategies: one fast‐growing, early successional, with high dispersal, and the other slow‐growing, stress‐tolerant, that recruit in shaded conditions.Main conclusionsEarth system models currently assume that reproductive allocation is indifferent among plant functional types. Easily measurable seed size is a strong predictor of the seed number and species seed productivity. The connection of SSP with the functional traits can form the first basis of improved fecundity prediction across global forests.

Seed traits and tropical arboreal species conservation: a case study of a highly diverse tropical humid forest region in Southern Costa Rica

Tropical areas are vital for conserving endangered tree species. However, barriers to the propagation and storage of plant material still limit preservation outcomes. Seed traits are essential in conservation but have rarely been applied in the tropics. In this work, we compile information about the germination and seed desiccation tolerance behaviour of 953 arboreal species from the Osa Peninsula, Costa Rica. We analysed how those traits are related to the growing strata, seed size, and dispersal mode and how they can be used to improve conservation initiatives based on the species distribution, abundance, extinction risk, and ex situ cultivation. Over a third of the species are probably recalcitrant but this number increase to almost half among the endangered and endemic ones. Most species have seeds dispersed by animals, but wind dispersal is usually orthodox and dominant in secondary forests. All species with tiny seeds and most understorey ones with small seeds are orthodox. Approximately half of the species have dormant seeds, while nearly one-third of nondormant species have cohorts with extended germination. Almost half of the species are conserved ex situ; however, several endangered, endemics could be expected to be considered exceptional. Seed traits could target orthodox species for seed banking in tropical forests, including the potential of secondary forests and a subset of oligarch species. For the recalcitrant ones, approaches based on the risk of extinction, distribution, abundance, and ex situ status allow for prioritizing collection and conservation strategies. Under this approach, we develop a list with priority species.

Assessment of the variability of the morphological traits and differentiation of Cucurbita moschata in Cote d’Ivoire

With its predisposition to adapt to different environments, Cucurbita moschata grows well in various ecosystems. It is not a very exigent plant and has an inherent capacity for plasticity that underlies its large variability. An assessment of the accessions of C. moschata in Cote d’Ivoire shows that the plant exhibits large morphological and phenological variability for all the 28 measured traits. There are outliers among most measured traits. Further analysis indicates the emergence of three ecotypes in congruence with the three distinct ecosystems and their respective bioclimatic characteristics. In the savannah region, characterized by a short rainy season followed by a long dry season, a total yearly rainfall of 900 mm, an elevated daily temperature of 29 °C, and a high relative humidity of 80%, the cline of C. moschata is long and thin, with small leaves, small peduncles and small fruits. It has a high growth rate and accelerated phenology. The mountain region has a very long rainy season followed by a short dry season, a total pluviometry of 1400 mm, an average daily temperature of 27 °C and a relative humidity of 69%. The cline of C. moschata in the mountain region is characterized by a delayed flowering and a delayed fruit maturity, large number of small seeds and large fruits. The forest region has a favorable climate for the growth of C. moschata in Cote d’Ivoire. It has two rainy seasons that alternate with two dry seasons of unequal durations, an annual rainfall of 1200 mm, an average daily temperature of 27 °C and a relative humidity of 70%. The cline of C. moschata in that region has a large girth size, large dimensions of the leaves, long peduncles and larger and heavier fruits. The seeds are also large but in small number. It appears that the anatomy and physiology of the clines are differentiated primarily in response to soil water content and availability for the ontogeny of the plant.

Temporal changes in the dominance of tree functional traits, but no changes in species diversity during woody plant encroachment in a Brazilian savanna

AbstractQuestions: Woody encroachment in savannas has been associated with changing taxonomic composition and ecosystem function. Interestingly, there is little understanding of how encroachment impacts plant functional diversity and how those changes relate to plant demography, a crucial mediator between taxonomic composition and ecosystem function.Location: Southeastern Brazil.Methods: Using a landscape scale fire suppression experiment in a diverse Brazilian savanna, we quantify how change in species composition over seven years impacted vegetative and reproductive tree functional diversity as determined by new recruits, dead and surviving trees.Results: Over seven years, tree above‐ground biomass increased by 15%, while total species richness did not change. Despite minor changes, species composition remained overall similar (82%), with few species contributing significantly to plot dissimilarity over time. There were small changes in vegetative traits, where the community‐weighted mean increased in maximum tree height (↑ 2.1%) and specific leaf area (↑ 5.3%), and decreased in wood density (↓ 1.3%) and bark thickness (↓ 9.4%). Changes in reproductive traits were larger than in vegetative traits, with an increase in the prevalence of monoecy (↑ 32.6%), dioecy (↑ 44.2%), large seeds (↑ 20.3%), animal‐mediated seed dispersal (↑ 4.9%) and pollination by very small insects (↑ 45.5%), and a decrease in the prevalence of hermaphroditism (↓ 9%), small seeds (6.8%) and pollination by small insects (12.5%). The overall decrease in bark thickness and increase in monoecy and dioecy were mainly driven by characters of the new recruits, while the overall increase in specific leaf area (SLA) and decrease in small seeds appeared largely determined by the loss of trees possessing those traits.Conclusions: Encroachment leads to changes that are likely increasing ecosystem vulnerability to fire and drought. Further, the compositional changes observed appear to drive marked change in reproductive traits, indicating increasing dependence on animals for dispersal and reproduction. Understanding post‐hoc encroachment impacts in an era of widespread pervasive encroachment is fundamental to reconciling ecosystem functions such as nutrient cycling and pollination services as there is a loss of species with open ecosystem life‐history strategies. Among savannas, there remains an urgent need to understand relationships between woody cover and ecosystem function to determine thresholds in woody cover promoting resilient savanna ecosystems.

Identification and Pyramiding Major QTL Loci for Simultaneously Enhancing Aflatoxin Resistance and Yield Components in Peanut.

Peanut is susceptible to Aspergillus flavus infection, and the consequent aflatoxin contamination has been recognized as an important risk factor affecting food safety and industry development. Planting peanut varieties with resistance to aflatoxin contamination is regarded as an ideal approach to decrease the risk in food safety, but most of the available resistant varieties have not been extensively used in production because of their low yield potential mostly due to possessing small pods and seeds. Hence, it is highly necessary to integrate resistance to aflatoxin and large seed weight. In this study, an RIL population derived from a cross between Zhonghua 16 with high yield and J 11 with resistance to infection of A. flavus and aflatoxin production, was used to identify quantitative trait locus (QTL) for aflatoxin production (AP) resistance and hundred-seed weight (HSW). From combined analysis using a high-density genetic linkage map constructed, 11 QTLs for AP resistance with 4.61-11.42% phenotypic variation explanation (PVE) and six QTLs for HSW with 3.20-28.48% PVE were identified, including three major QTLs for AP resistance (qAFTA05.1, qAFTB05.2 and qAFTB06.3) and three for HSW (qHSWA05, qHSWA08 and qHSWB06). In addition, qAFTA05.1, qAFTB06.3, qHSWA05, qHSWA08 and qHSWB06 were detected in multiple environments. The aflatoxin contents under artificial inoculation were decreased by 34.77-47.67% in those segregated lines harboring qAFTA05.1, qAFTB05.2 and qAFTB06.3, while the HSWs were increased by 47.56-49.46 g in other lines harboring qHSWA05, qHSWA08 and qHSWB06. Conditional QTL mapping indicated that HSW and percent seed infection index (PSII) had no significant influence on aflatoxin content. Interestingly, the QT 1059 simultaneously harboring alleles of aflatoxin content including qAFTA05.1 and qAFTB05.2, alleles of PSII including qPSIIB03.1, qPSIIB03.2, and qPSIIB10 and alleles of HSW including qHSWA05, qHSWB06, qHSWA08 had better resistance to A. flavus infection and to toxin production and higher yield potential compared with the two parents of the RIL. The above identified major loci for AP resistance and HWS would be helpful for marker-assisted selection in peanut breeding.

Big Tree by Brian Selznick

Reviewed by: Big Tree by Brian Selznick April Spisak Selznick, Brian Big Tree; written and illus. by Brian Selznick. Scholastic, 2023 [528p] Trade ed. ISBN 9781338180633 $32.99 Reviewed from digital galleys R* Gr. 5-7 Louise and her brother, Merwin, never expected to be apart from their mom so young—they are still quite small Sycamore seeds when a fire leaves them alone in a giant and dangerous world. This world is full of terrors even if you aren’t a little seed, but for them water and wind can be risky, not to mention the dinosaurs and volcanoes. Louise is optimistic, trusting that her vibes will get her where she is destined to grow. Merwin is far more skeptical and fearful, but their love and mutual respect for each other lasts through separations, harrowing adventures, and, ultimately, two very different timelines for planting roots and becoming trees. The [End Page 232] story is unrushed, moving at a measured pace that encourages contemplation and patience: nature can be quick and wild, but trees will not be hurried. Selznick’s dedication to dual storytelling through text and hundreds of finely detailed pencil drawings allows for each to progress the plot in succession, creating a balanced and rich book that invites careful reading and poring over illustrations to find all of the connective threads. An author’s note describes how the pandemic derailed this Steven Spielberg idea from becoming a movie and how Selznick then adapted their project into a book. His expressive art that highlights the heart of the story, paired with his keen eye for creating sympathetic and memorable lost children (here he subbed in seeds for the kids) are a powerful combination to bring to this epic quest. Selznick fans will be delighted, and dinosaur fans and nature buffs will likely be just as enthralled. Copyright © 2023 The Board of Trustees of the University of Illinois

Soil texture involvement in wildflower strip ecosystem services delivery in Mediterranean agro-environment

The biodiversity restoration of the agroecosystem through wildflower strips is one of the most important agronomic strategies of the last few decades. However, poor knowledge of the bio-agronomic characteristics of the various wildflower species often leads to suboptimal performances especially as a result of their poor seed germination and poor seedling emergence due to the erratic soil texture. A two-year experiment involving the sowing of eighteen wildflower species in different texture conditions highlighted how some species emerged earlier or more effectively than others and verifying the consequent ecosystem service provided to pollinators. Species with smaller seeds were more inhibited by sowing in soil with high content of clay. Additionally, an inverse relationship (Boltzmann's sigmoidal regression) was found between seed weight and soil-mediated inhibition. This soil-mediated inhibition was higher in the clayey textured soil, showing that this inhibition was mediated both by seed weight and by the clay particles of the soil. The reciprocal interference between the emerged seedlings also determined a further decline in the wildflower species with small seeds. This differing agronomic performance, after sowing in the two different soil textures, did not affect the number of pollinator visits. Performance differed both in terms of floristic biodiversity and pollinator biodiversity. Finally, the experiment highlighted the importance of the appropriate selection of the wildflower species for biodiversity restoration - not only in terms of pollen and nectar availability for pollinators, but also in terms of compatibility with the soil texture in which the wildflower seeds are sown.

Veronicahongii (Plantaginaceae), a new species from Central China.

A new species Veronicahongii, from western Hubei Province, Central China is described and illustrated. The species is morphologically similar to V.henryi Yamazaki, but mainly differs in the glabrous plant, except pedicels, broadly ovate leaf blades, glandular-pubescent pedicels, obovate calyx lobes, smaller corolla, broadly ovate capsule and much smaller seeds.

Soybean seed protein content is lower but protein quality is higher in Western Canada compared with Eastern Canada

Low seed protein content in soybeans [ Glycine max (L.) Merr.] grown in Western Canada can result in soybean meal that does not meet the 48% protein standard. The objectives of this study were to quantify seed composition, agronomic differences between Eastern and Western Canada-grown soybeans, and to determine the yield cost of raising Western soybean protein. Twenty high-to-low protein, including one non-nodulating, genotypes were grown at two locations in Eastern Canada, and eight locations in Western Canada from 2018 to 2021 to determine seed protein, seed composition, and agronomic traits. Over all environments, genotype seed protein ranged from 36.8% to 46.9% with 35.0% for the non-nodulating line. Average seed protein was significantly higher in Eastern Canada (41.6%) compared with Eastern Prairie (39.3%) and Prairie sites (39.7%). There are not separate east–west mega-environments for seed protein in Canada; a high protein genotype is high protein across Canada. With an increase of seed protein by 1%, seed yield dropped by 45.3 kg ha−1 in Eastern Canada, 53.1 kg ha−1 in the Eastern Prairie, and 78.4 kg ha−1 in Prairie sites. In Western Canada, plants were taller but lower yielding with fewer and smaller seeds, and produced lower fixed nitrogen protein yield compared with Eastern Canada. Seed protein quality, quantified with the 11S:7S ratio, was higher in Western Canada compared with Eastern Canada. Plant breeders and growers may need to select higher protein genotypes at the cost of lower yield, if the soybean industry is unable to exploit the protein quality advantage in Western Canada.

Characterization of Seed Oil from Six In Situ Collected Wild Amaranthus Species

Six Amaranthus species (A. cruentus, A. hybridus, A. hypochondriacus, A. muricatus, A. tuberculatus, and A. viridis) were collected in Italy (wild habitats) from crops and roadsides. Amaranth seed oil was extracted to obtain fractions rich in squalene. Squalene, free fatty acid, tocopherol, and sterol composition and content were investigated in detail. An analysis of variance and principal components was performed. The oil content in the seed ranged from 5.17% (A. muricatus) to 12.20% (A. tuberculatus). The quantity of squalene in the oil varied from 3.43% (A. muricatus) to 6.09% (A. hypochondriacus). The primary sterols were beta-sitosterol, brassicasterol, campesterol, and stigmasterol. The main tocopherols in all the samples were alfa-tocopherol, beta-tocopherol, and delta-tocopherol. Our results exhibited that the smallest seeds (A. tuberculatus) have the highest percentages of oil and squalene, whereas the largest seeds size (A. muricatus) show the lowest percentages. There is also evidence that the samples growing at lower altitudes show the highest concentration of fatty acids. According to our results, the six wild Amaranthus species exhibited similar characteristics to commercial species. This study confirms that the site of the collection has an impact on the oil and squalene content of the Amaranthus species.

Differences in mating system and predicted parental conflict affect post-pollination reproductive isolation in a flowering plant.

Mating system shifts from outcrossing to selfing are frequent in plant evolution. Relative to outcrossing, selfing is associated with reduced parental conflict over seed provisioning, which may result in postzygotic, asymmetric, reproductive isolation in crosses between populations of different mating systems. To test the hypothesis that post-pollination reproductive isolation between populations increases with increasing differences in mating system and predicted parental conflict, we performed a crossing experiment involving all combinations of three self-compatible populations (with low outcrossing rates), and three self-incompatible populations (with high outcrossing rates) of the arctic-alpine herb Arabis alpina, assessing fitness-related seed and plant traits of the progeny. Predicted levels of parental conflict ("genome strength") were quantified based on strength of self-incompatibility and estimates of outcrossing rates. Crosses between self-compatible and self-incompatible populations yielded very small seeds of low viability, resulting in strong reproductive isolation. In 14 of 15 reciprocal between-population crosses, seeds were heavier when the paternal plant had the stronger genome, and seed mass differences between cross directions increased with an increased difference in parental conflict. Overall, our results suggest that, when sufficiently large, differences in mating system and hence in expected parental conflict may result in strong post-pollination reproductive barriers contributing to speciation.

Cold stratification requirement to break morphophysiological dormancy of fennel (Foeniculum vulgare Mill.) seeds varies with seed length

Seed germination plays a significant role in establishment and growth of seedlings. Two factorial experiments were conducted to investigate seed dormancy and germination in fennel (Foeniculum vulgare Mill.) seeds. The first experiment evaluated cold stratification (0, 2, 4, 6, and 8 weeks), gibberellic acid (0, 500, and 2000 ppm), genotypes ('Chahestan' and 'Fasa'), and incubation temperatures (10, 20, and 30 °C). The second experiment examined the effects of cold stratification (0, 2, 4, 6, and 8 weeks), genotypes ('Chahestan' and 'Fasa'), and seed length (large (>4.7 mm), medium (3– 4.7 mm), and small (2–3 mm)). The results from the first experiment showed that the fennel seeds have linear underdeveloped embryos with an embryo length to seed length ratio (E/S ratio) of 0.24–0.28. Four weeks after cold stratification, embryos typically reached to ∼2.5 mm length with an E/S ratio of ∼0.6, and germination percentages of 70%, and 85% in 'Chahestan' and 'Fasa' (treated with 2000 ppm GA3 and incubated at 10 °C). GA3 improved the germination percentage and germination rate, but could not substitute for cold stratification. Thus, seeds of fennel have non-deep simple of morphophysiological dormancy (MPD). In the second experiment, we found that across all stratification periods, large seeds had longer embryos than medium and small seeds, but the E/S ratio was lower in large seeds than small seeds, showing more morphological dormancy part in large seeds than small seeds. In addition, E/S ratio also peaked in the fourth week of stratification, and after four weeks of stratification, the difference between E/S ratio was not significant. The small seeds have more physiological dormancy part than larger ones. Seed germination was significantly higher in large seeds than in small seeds. More than 70% of large seeds in both genotypes germinated without stratification. Thus, it can be concluded that larger seeds have less physiological dormancy part than smaller ones. To cultivate this medicinal plant, it would be beneficial to use large seeds to ensure a better germination and seedling establishment.

Astragalusbashanensis (Leguminosae), a new species from Central China.

A new species Astragalusbashanensis, from western Hubei Province, Central China is described and illustrated. The new species is morphologically similar to Astragalussinicus and A.wulingensis, but differs from both by its spreading pubescent indumentum on stems and petioles, longer petioles, white bracts, whitish or yellow corolla, longer claw of the keel-petal, hairy pods and smaller seeds.

An Economic Method to Identify Cultivars and Elite Lines in Radish (Raphanus sativus L.) for Small Seed Companies and Independent Breeders

Radish is a root vegetable crop, and many F1 cultivars have been developed by exploiting heterosis. Considerable time and resources are required to test the performance and combining ability of F1 cultivars and parental lines; therefore, economical methods to identify them are needed before field tests. This study was conducted to determine the minimum number of markers needed to identify cultivars and elite lines. PCR-based markers were applied to radish cultivars and elite lines and selected based on chromosomal location, polymorphic information content, and allele frequency. The power of selected marker sets to detect genetically similar cultivars or elite lines was confirmed using cultivars with high genetic similarity and elite lines with the same parents. Eleven markers successfully identified not only all 105 radish cultivars tested but also cultivars with high genetic similarity reported in previous studies. Fourteen markers, including the nine among 11 markers for cultivar identification, also successfully distinguished all 115 elite lines tested, including ones with the same parents and separated at F2–F6 generations. The markers developed for the identification of radish cultivars and elite lines require only 11 and 14 markers, respectively, and simple PCR and gel electrophoresis instruments. This method is very simple and can be easily applied to other crops.

Synthesis of thin DD3R zeolite membranes on hollow fibers using gradient-centrifuged seeds for CO2/CH4 separation

All-silica DD3R zeolite has been recognized as a promising CO2-selective membrane material owing to its appropriate pore size (0.36 nm × 0.44 nm), strong hydrophobicity, excellent thermal and chemical stabilities. In order to reduce membrane cost, it is meaningful to synthesize thin DD3R zeolite membranes that possess high gas permeance. In this work, high-performance DD3R zeolite membranes were synthesized on TiO2/α-Al2O3 composite hollow fibers by secondary growth method. Sigma-1 zeolite seeds were ball-milled and then fractionated into different-sized seeds by gradient centrifugation. Smaller seed particles were collected after centrifuged at higher rotation speed rate. A very thin and dense DD3R zeolite membrane (thickness: 1.2 µm) was synthesized by using the smallest seeds (ZS4) with average particle size of 163 nm, which were obtained from the supernatant of the third centrifugation at 11,000 rpm. The as-synthesized membranes were employed in separation of equimolar CO2/CH4 mixture. Compared with the original ball-milled seeds (ZS1)-induced membrane, the seed ZS4-induced membrane exhibited an improved CO2 permeance of 1.2 × 10−7 mol m−2 Pa−1 s−1 by 62%. All the resultant membranes performed good CO2/CH4 separation selectivities between 262 and 364.

Overexpression of the Ginkgo biloba dihydroflavonol 4-reductase gene GbDFR6 results in the self-incompatibility-like phenotypes in transgenic tobacco

ABSTRACT Although flavonoids play multiple roles in plant growth and development, the involvement in plant self-incompatibility (SI) have not been reported. In this research, the fertility of transgenic tobacco plants overexpressing the Ginkgo biloba dihydroflavonol 4-reductase gene, GbDFR6, were investigated. To explore the possible physiological defects leading to the failure of embryo development in transgenic tobacco plants, functions of pistils and pollen grains were examined. Transgenic pistils pollinated with pollen grains from another tobacco plants (either transgenic or wild-type), developed full of well-developed seeds. In contrast, in self-pollinated transgenic tobacco plants, pollen-tube growth was arrested in the upper part of the style, and small abnormal seeds developed without fertilization. Although the mechanism remains unclear, our research may provide a valuable method to create SI tobacco plants for breeding.

Evolution of the Cotton Genus, Gossypium, and Its Domestication in the Americas

Gossypium, the cotton genus, includes ∼50 species distributed in tropical and sub-tropical regions of all continents except Europe. Here we provide a synopsis of the evolutionary history of Gossypium and domestication of the American allopolyploid species, integrating data from fundamental taxonomic investigations, biogeography, molecular genetics, phylogenetic analysis, and archaeology. These diverse sources of information provide a temporal and phylogenetic perspective on diversification among the diploids and on polyploid formation, uncover multiple previously cryptic interspecific hybridizations, clarify and contribute to the taxonomy of the genus, and offer a firm foundation for understanding parallel domestications in Mesoamerica and South America, which led to the globally important cotton crop species G. barbadense and G. hirsutum. Gossypium thus offers a testimonial example of the importance and utility of fundamental botanical discovery combined with modern technological capabilities to generate genomic insights into evolutionary history. We also review the current state of our knowledge regarding the archaeological history of cotton domestication and diffusion in the Americas, a seemingly unlikely story entailing parallel domestication origins and parallel directional selection tracing to 8,000 (G. barbadense) and 5,500 (G. hirsutum) years ago, transforming two geographically isolated wild short-day perennial shrubs having small capsules and seeds covered by short, tan-colored epidermal trichomes into modern daylength-neutral annuals bearing abundant, fine, strong white fibers. This dual domestication was followed several millennia later by unintentional and more recently intentional interspecific introgression, as the two species came into contact following their initial domestication in different hemispheres. Thus, the cycle of species divergence and biological reunion was reiterated, this time at the allopolyploid level. Understanding this evolutionary history is vitally important to our understanding of the genomic architecture of the world’s most important fiber plant and contributes substantially to our understanding of general biological principles.

Environmental Variation in Seed Mass in Sanguisorba Minor

ABSTRACT: Seed mass is an important characteristic of seed quality because larger seeds contain more resources and are likely to exhibit greater vigor than smaller seeds, characteristics that are commonly targeted in plant breeding programmes. Seed mass variation in 359 populations (accessions) of Sanguisorba minor were evaluated across its geographical range in Iran. In addition, the seed and germination parameters of 13 populations that had been stored for 12 years at 4°C in the Natural Resources Gene Bank of Iran were analysed. Seed mass among the 359 populations varied from 1.4g to 14.5g with an average of 5.65g. In this study, the seed mass variation was compared with eco-geographical variables across the original habitats of S. minor . An increase in the maximum temperature of the warmest month, annual precipitation, precipitation of the wettest month, precipitation of the wettest quarter and precipitation of the coldest quarter led to increases in seed mass. Smaller seeds were produced in the hotter and drier environments located in the center of Iran, and in wetter sites. Significant differences in seed traits were found among the 13 stored populations of S. minor and seed germination was positively corrrelated with seed mass (R2 = 0.9). The highest germination percentage after 12 years of storage was obtained in the Hamedan (75%) and Chaharmahal and Bakhtiari (74%) populations, which had heavier and larger seeds. The positive correlation between longevity in ex-situ facilities and seed mass, suggests heavier seeds may have an advantage during storage and for use in breeding programmes.