Capacity For Sexual Reproduction Research Articles

A haplotype-resolved genome assembly of Coptis teeta, an endangered plant of significant medicinal value

Coptis teeta Wall. (Ranunculaceae), an endangered plant species of significant medicinal value, predominantly undergoes clonal propagation, potentially compromising the species’ evolutionary potential and ultimately increase its risk of extinction. In this study, we successfully assembled two sets of haploid genomes (Hap1 and Hap2) for C. teeta, comprising nine homologous chromosome pairs, by employing Illumina and PacBio sequencing technologies. The genome annotation identified a total of 43,979 and 46,311 protein-coding genes in Hap1 and in Hap2, and most of them were functionally annotated. The high-quality reference genome will serve as an indispensable genomic resource for conservation and comprehensive exploitation of this endangered species. Between the two haploid genomes, numerous structural alterations were detected within the nine homologous chromosome pairs, potentially resulting in aberrant synapsis and irregular chromosomal segregation and thus contributing to the sustained preservation of clonal propagation in C. teeta. The findings offer new perspective for elucidating the genetic mechanism underlying the compromised sexual reproductive capacity of C. teeta, thereby facilitating its enhancement though molecular breeding and genetic improvement.

Possible germline progenitor cells in extra-gonadal tissues of the sea anemone, Exaiptasia diaphana

Many anthozoans, e.g., sea anemones and corals, have remarkable capacities for asexual reproduction and regeneration, creating complete individual polyps from pieces of parental polyp tissue. Notably, polyps produced asexually (or regenerated) from somatic tissues that originally contain no gonads are capable of sexual reproduction. However, how somatically derived polyps can reproduce remains largely unexplored. Here, using a sea anemone, Exaiptasia diaphana, we show that potential germline progenitor cells are present in the extra-gonadal tissues, and that they are allocated to newly produced individuals during asexual reproduction/regeneration. Histological analysis of E. diaphana demonstrated that polyps asexually produced from pedal lacerates can create mature gametes. Amputation experiments showed that polyps regenerated from the head, which originally lacked gonadal tissue, formed gonads and initiated gametogenesis. Immunohistochemical analysis with a germline marker, vasa, demonstrated the presence of vasa-positive cells in various polyp tissues. These findings suggest that vasa-positive cells in extra-gonadal tissues may be a reservoir of germline progenitor cells to ensure sexual reproductive capacity in individuals produced asexually or regenerated from somatic tissues.

Fruit and seed morphological divergence between wild and cultivated enset (Ensete ventricosum [Welw.] Cheesman)

Enset is a single-stemmed plant; i.e., non-suckering naturally both in wild and cultivated states. There are great differences in their life cycles between the wild and cultivated populations of enset. Wild enset reproduce naturally via seeds. As cultivated enset is usually harvested before or shortly after flowering, the development of flowers and fruits is rarely encountered in cultivation. As a result, cultivated enset is propagated vegetatively, with adventitious buds sprouting from the corm after the removal of the apical meristem. In vegetatively propagated crops, the loss of sexual reproduction capacity has been recognized as a domestication syndrome. The present study was performed to determine the pattern of fruit and seed variation between and within wild and cultivated populations, by measuring morphological differences in fruit and seed traits (number of hands per bunch, number of fruit per mid-hand, mean fruit weight, fruit length, fruit circumference, seed number per fruit, seed weight and seed diameter) in wild and cultivated plants. Results of pairwise PERMANOVA comparisons showed significant difference between wild and domesticated enset in terms of their fruit and seed morphological characters. Among the traits studied, average fruit weight, fruit length, fruit circumference, and number of seeds per fruit were the traits that differed most between cultivated and wild. These characters were significantly greater in the wild population than in cultivated. We suggest that these traits could define the domestication syndrome of this plant. Despite significant divergences between wild and cultivated ensets, some cultivated accessions, were certainly domesticated landrace are placed together with wild accessions in PCA biplot. Our results point to the possibility of complex evolutionary dynamics of both cultivated and wild forms, and gave an insight that there is huge potential to improve this crop through hybridization and clonal selection methods. Furthermore, the present results provide useful indications on how to act for more rational planning in reproductive material management and genetic resource conservation strategies.

Capitulum Development and Gametophyte Ontogeny: Histological Insight into the Reproductive Process of a Hexaploidy Population of Solidago canadensis in China.

Solidago canadensis L., native to North America, has become a troublesome invasive plant worldwide due to its strong sexual reproductive capacity. Although there have been studies on some stages of sexual reproduction, there has been no systematic description of the process. In this study, we observed capitulum development, the occurrence of megasporogenesis and microsporogenesis, and embryo development using a scanning electron microscope. The results showed that there was a close relationship between the length of the capitulum bud and the stage in the reproductive process. Capitulum development appeared when the length of the capitate inflorescence was less than 1.73 ± 0.08 mm. The meiosis of microspores occurred when the length of the capitate inflorescence ranged from 2.20 ± 0.07 mm to 3.50 ± 0.10 mm, and mature pollen grains and embryo sacs formed when the length of the capitate inflorescence was greater than 5.15 ± 0.14 mm. Based on the available information, a reproductive calendar showing the key reproductive events from capitulum development to seed formation has been prepared. These processes may be related to its inherent temperature adaptation and non-synchronization of flowering, which may avoid embryo abortion during embryo development and consequently as a key step for its successful invasion in China. These results open up new horizons for effective prevention and control of spread in the future.

Reproductive biology of wild and domesticated Ensete ventricosum: Further evidence for maintenance of sexual reproductive capacity in a vegetatively propagated perennial crop.

Loss of sexual reproductive capacity has been proposed as a syndrome of domestication in vegetatively propagated crops, but there are relatively few examples from agricultural systems. In this study, we compare sexual reproductive capacity in wild (sexual) and domesticated (vegetative) populations of enset (Ensete ventricosum (Welw.) Cheesman), a tropical banana relative and Ethiopian food security crop.We examined floral and seed morphology and germination ecology across 35 wild and domesticated enset. We surveyed variation in floral and seed traits, including seed weight, viability and internal morphology, and germinated seeds across a range of constant and alternating temperature regimes to characterize optimum germination requirements.We report highly consistent floral allometry, seed viability, internal morphology and days to germination in wild and domesticated enset. However, seeds from domesticated plants responded to cooler temperatures with greater diurnal range. Shifts in germination behaviour appear concordant with a climatic envelope shift in the domesticated distribution.Our findings provide evidence that sexual reproductive capacity has been maintained despite long‐term near‐exclusive vegetative propagation in domesticated enset. Furthermore, certain traits such as germination behaviour and floral morphology may be under continued selection, presumably through rare sexually reproductive events. Compared to sexually propagated crops banked as seeds, vegetative crop diversity is typically conserved in living collections that are more costly and insecure. Improved understanding of sexual propagation in vegetative crops may have applications in germplasm conservation and plant breeding.

Seed Production and Floral Visitors to Pityopsis ruthii (Asteraceae: Asterales), an Endangered Aster Native to the Southern Appalachians

Pityopsis ruthii (Small) Small (Asteraceae: Asterales) is a federally endangered aster that only grows along short stretches of the Hiwassee and Ocoee Rivers in southeastern Tennessee, U.S.A. The species is self-incompatible and genetic drift and inbreeding depression have been reported. Multiple investigators have observed highly variable sexual reproductive capacity of P. ruthii. To better understand which insect species may be contributing roles as potential pollinators, floral visitation to P. ruthii was assessed at in situ and ex situ locations. Forty-seven insect species in 15 families and 3 orders were recovered across 2 years during more than 70 hours of observation and specimen collection. Megachile brevis Say (Megachilidae: Hymenoptera) carried the most pollen, yet just three specimens were collected, all from the ex situ location. In both years, Halictidae were common at the ex situ location and were infrequently collected at the in situ location. Apis mellifera L. (Apidae: Hymenoptera) and Bombus impatiens Cresson (Apidae: Hymenoptera) were commonly observed at in situ locations in both years, and in 2013 at the ex situ location. Toxomerus geminatus (Say) (Syrphidae: Diptera) was the most abundant floral visitor in both years but carried very little pollen. Floral visiting lepidopteran species carried no pollen. Greater numbers of P. ruthii inflorescences did not reliably influence Apoidea or Syrphidae floral visitor abundance in either the in situ or ex situ locations. Assessments of filled seeds revealed low germination rates. Hybridization between geographically disparate parent plants propagated from the distal ranges of Hiwassee River distribution yielded an average of 33 percent germination, validating evidence of inbreeding depression. Knowledge of P. ruthii floral visitors at in situ and ex situ locations can be employed to assist breeding efforts intended to increase genetic diversity through ongoing efforts in plant re-introduction and habitat management.

Genetic variation and population structure of clonal Zingiber zerumbet at a fine geographic scale: a comparison with two closely related selfing and outcrossing Zingiber species

BackgroundThere has always been controversy over whether clonal plants have lower genetic diversity than plants that reproduce sexually. These conflicts could be attributed to the fact that few studies have taken into account the mating system of sexually reproducing plants and their phylogenetic distance. Moreover, most clonal plants in these previous studies regularly produce sexual progeny. Here, we describe a study examining the levels of genetic diversity and differentiation within and between local populations of fully clonal Zingiber zerumbet at a microgeographical scale and compare the results with data for the closely related selfing Z. corallinum and outcrossing Z. nudicarpum. Such studies could disentangle the phylogenetic and sexually reproducing effect on genetic variation of clonal plants, and thus contribute to an improved understanding in the clonally reproducing effects on genetic diversity and population structure.ResultsThe results revealed that the level of local population genetic diversity of clonal Z. zerumbet was comparable to that of outcrossing Z. nudicarpum and significantly higher than that of selfing Z. corallinum. However, the level of microgeographic genetic diversity of clonal Z. zerumbet is comparable to that of selfing Z. corallinum and even slightly higher than that of outcrossing Z. nudicarpum. The genetic differentiation among local populations of clonal Z. zerumbet was significantly lower than that of selfing Z. corallinum, but higher than that of outcrossing Z. nudicarpum. A stronger spatial genetic structure appeared within local populations of Z. zerumbet compared with selfing Z. corallinum and outcrossing Z. nudicarpum.ConclusionsOur study shows that fully clonal plants are able not only to maintain a high level of within-population genetic diversity like outcrossing plants, but can also maintain a high level of microgeographic genetic diversity like selfing plant species, probably due to the accumulation of somatic mutations and absence of a capacity for sexual reproduction. We suggest that conservation strategies for the genetic diversity of clonal and selfing plant species should be focused on the protection of all habitat types, especially fragments within ecosystems, while maintenance of large populations is a key to enhance the genetic diversity of outcrossing species.

Appropriate nitrogen addition regulates reproductive strategies of Leymus chinensis

Nitrogen(N) addition can significantly improve the aboveground productivity of plants. The responses of reproductive strategies to N addition remain elusive for Leymus chinensis. Here, we examined the vegetative growth and clonal and sexual reproduction of a rhizome clonal grass, Leymus chinensis (Trin.) Tzvel, in response to N addition rates of 0, 2, 4, 8, 16, 32, and 64 g N m−2. N addition altered the reproductive strategy and allometric growth patterns of L. chinensis along the N addition gradient. N addition generally promoted higher investment in the biomass of vegetative and clonal organs, and a lower investment in sexual organs. N addition rates of 16 and 32 g N m−2 were key thresholds; 16 g N m−2 was the optimal rate for sexual reproduction and 32 g N m−2 was optimal for vegetative growth and clonal reproduction. At an addition rate of 16 g N m−2, the sexual reproductive capacity of L. chinensis was highest. Resource allocation to sexual reproduction increased with N addition, but decreased at rates>16 g N m−2. The growth and clonal reproduction of L. chinensis decreased at N concentrations>32 g N m−2. Our findings highlight that the reproductive strategy of L. chinensis varies with N addition rate, and the growth, sexual reproduction, and clonal reproduction strategies of L. chinensis are plastic, which has important implications for production.

Variation in sexual reproductive output among exotic taxa of Spartina (Poaceae)

Sexual reproduction can enhance the colonization and spread of invasive plants. We aimed to evaluate ecological factors influencing sexual reproduction and dispersal capacity of exotic Spartina taxa. Density of inflorescences, spikelets per inflorescence, percentage of spikelets with caryopses, and density of caryopses were recorded for North American S. patens, South American S. densiflora, and reciprocal hybrids of invasive S. densiflora with native S. maritima in salt marshes at the Gulf of Cadiz. For S. patens and hybrids, we also assessed pollen viability, and the percentages of reabsorbed caryopses and spikelets with all stamens exserted. For fertile S. densiflora, we evaluated plant sexual traits and characteristics of the sedimentary environment, and conducted germination experiments. We found interannual variation for reproductive traits of S. densiflora which also differed among habitats. Plants with highest inflorescence and caryopsis densities occupied low marshes and saltpans, lowest caryopsis production was in low marsh where abiotic stress was high, while viability of caryopses tended to be the highest in middle and high marshes. Our results indicate neither hybrid produced any mature caryopses, due to lack of pollen viability. However, male fitness did not explain infecundity of S. patens with ca. 80% of spikelets with all stamens exserted and pollen viability was ca. 60%. To reduce invasive spread and impact, conservation efforts to protect biodiversity should prioritize rapid eradication of Spartina hybrids before they attain sexual reproductive capacity. The removal of S. densiflora within 2 years of establishment before production of viable caryopses is strongly recommended.

Accumulation of mutations in genes associated with sexual reproduction contributed to the domestication of a vegetatively propagated staple crop, enset

Enset (Ensete ventricosum (Welw.) Cheesman) is a drought tolerant, vegetatively propagated crop that was domesticated in Ethiopia. It is a staple food for more than 20 million people in Ethiopia. Despite its current importance and immense potential, enset is among the most genetically understudied and underexploited food crops. We collected 230 enset wild and cultivated accessions across the main enset producing regions in Ethiopia and applied amplified fragment length polymorphism (AFLP) and genotype by sequencing (GBS) analyses to these accessions. Wild and cultivated accessions were clearly separated from each other, with 89 genes found to harbour SNPs that separated wild from cultivated accessions. Among these, 17 genes are thought to be involved in flower initiation and seed development. Among cultivated accessions, differentiation was mostly associated with geographical location and with proximity to wild populations. Our results indicate that vegetative propagation of elite clones has favoured capacity for vegetative growth at the expense of capacity for sexual reproduction. This is consistent with previous reports that cultivated enset tends to produce non-viable seeds and flowers less frequently than wild enset.

Restoration Affects Sexual Reproductive Capacity in a Salt Marsh

Plant sexual reproduction is an important driver of plant community maintenance, dispersal, and recovery from disturbance. Despite this, sexual reproduction in habitats dominated by clonally spreading perennial species, such as salt marshes, is often ignored. Communities dominated by long-lived perennial species can still depend on sexual reproduction for recolonizing large disturbed patches or for establishing in new patches, such as restored sites. We investigated the influence of restoration and elevation on flowering phenology, potential seed and seedling production, and insect flower damage of the dominant salt marsh grass, Spartina alterniflora, in reference and restored marshes in southeastern Louisiana, USA. We additionally tested whether elevation gradients or soil parameters could explain differences in sexual reproduction between sites. We demonstrate that sediment-slurry amendment restoration may not affect flowering phenology or insect flower damage at ecologically relevant levels, but that restoration activity increases sexual reproductive output at the patch scale. Restoration activity affected reproductive dynamics more often than changes in elevation alone. Restoration of subsiding salt marsh habitat by altering the soil environment may increase sexual reproductive capacity of these wetlands.

Genetic diversity and stand structure of neighboring white willow (Salix alba L.) populations along fragmented riparian corridors: a case study

Abstract Remnant riparian woodlands have an important landscape function, due to their ability to act as ecological corridors. In this study we used molecular markers to assess the genetic variation occurring within and between spontaneous white willow (Salix alba L.) riparian woodlands. Our main goal was to evaluate the extent to which the fragmentation of a woodland corridor along a heavily impacted river in northeastern Italy and stand structural conditions may have affected the population genetics. Although having different structures, the three examined white willow stands showed high estimates of genetic similarity, as well as low genetic differentiation between them, indicating that they shared a similar gene pool and that the stands could result from a common set of individual genotypes, and should be regarded as metapopulations. The magnitude of genetic diversity within each of the stands and genetic differentiation between them, despite their high sexual reproductive capacity associated with a highly marked gene flow, suggest that these stands are dynamic and capable of adaptive responses to possible changes in their fluvial environment. However, the factors influencing genetic diversity should be interpreted from a long-term perspective. Fluvial geomorphic patterns in regulated rivers may be modified to a degree that could lead to changes in dispersal processes, sexu­al reproduction vs. asexual propagation, and hence genetic diversity.

The dynamics of clonal dispersal and regenerative activity of Veronica filiformis J.E. Smith

The absence of capacity for sexual reproduction does not hinder the rapid expansion of the invasive range of the alien species Veronica filiformis J.E. Smith (Plantaginaceae). Lawn mowing or raking causes the fragmentation of shoots and accelerates vegetative reproduction of V. filiformis. The clone diameter of this species was shown to increase up to 25 times during the growing season, whereas the number of internodes increased by a factor of 1000–2000. Slender speedwell expanded from the site of initial introduction (Moscow, Russia) at the speed of 4 km/year in the northern direction and at a speed of 10 km/year in the southern direction. Illumination of the site had a more pronounced effect on the regenerative capacity of the species than the age of root-forming shoots. Invasion of meadow and forest fringe communities by this species was registered in recent decades. The high speed of expansion of the secondary distribution range, the displacement of native species, and the direct damage to lawns caused by this plant allow for the assignment of an invasive species status to V. filiformis and justify the control over the dispersal of this species.

Sexual reproduction of clonal dwarf shrubs in a forest–tundra ecotone

Successful sexual reproduction may be more important for regeneration of clonal species in high-latitude and -altitude areas than has been previously suggested. We investigated the potential of Vaccinium myrtillus, V. vitis-idaea and Empetrum nigrum ssp. hermaphroditum (E. hermaphroditum) for sexual reproduction at three sites in the forest–tundra ecotone in Finnish Lapland. We studied whether the potential differs between plant communities, whether disturbance enhances germination, and whether seedling emergence is limited by seed availability. We established a field experiment with disturbance and sowing treatments, and monitored seed and seedling numbers and survival rates for two years. The number of mature seeds of V. myrtillus was higher in plants from the tundra heath than in those from the coniferous and mountain birch forests. The number of mature seeds and seedlings emerging from the seed bank of E. hermaphroditum tended also to be higher in the tundra heath. Disturbance marginally increased the seedling emergence of V. myrtillus and E. hermaphroditum, whereas sowing generally increased the seedling numbers. The seedling number of V. myrtillus was lower in the tundra heath and that of E. hermaphroditum was lower in the coniferous forest than at the other sites. Seedling survival was equal for all plant species at all sites. We conclude that the capacity for sexual reproduction varies among plant communities, and seed availability is a stronger constraint than microsite availability for the studied species. Once the crucial early phase of seedling establishment is overcome, seedling survival enables successful recruitment of V. myrtillus, V. vitis-idaea and E. hermaphroditum in the subarctic area.

Tomato facultative parthenocarpy results from SlAGAMOUS-LIKE 6 loss of function.

SummaryThe extreme sensitivity of the microsporogenesis process to moderately high or low temperatures is a major hindrance for tomato (Solanum lycopersicum) sexual reproduction and hence year‐round cropping. Consequently, breeding for parthenocarpy, namely, fertilization‐independent fruit set, is considered a valuable goal especially for maintaining sustainable agriculture in the face of global warming. A mutant capable of setting high‐quality seedless (parthenocarpic) fruit was found following a screen of EMS‐mutagenized tomato population for yielding under heat stress. Next‐generation sequencing followed by marker‐assisted mapping and CRISPR/Cas9 gene knockout confirmed that a mutation in SlAGAMOUS‐LIKE 6 (SlAGL6) was responsible for the parthenocarpic phenotype. The mutant is capable of fruit production under heat stress conditions that severely hamper fertilization‐dependent fruit set. Different from other tomato recessive monogenic mutants for parthenocarpy, Slagl6 mutations impose no homeotic changes, the seedless fruits are of normal weight and shape, pollen viability is unaffected, and sexual reproduction capacity is maintained, thus making Slagl6 an attractive gene for facultative parthenocarpy. The characteristics of the analysed mutant combined with the gene's mode of expression imply SlAGL6 as a key regulator of the transition between the state of ‘ovary arrest’ imposed towards anthesis and the fertilization‐triggered fruit set.

Genetic diversity and reproductive traits in triploid and tetraploid populations of Gladiolus tenuis (Iridaceae)

Most perennial herbaceous plants are able to reproduce vegetatively as well as sexually. Sometimes, such plants may lose the capacity for sexual reproduction. We have studied the case of sterility in triploid populations (2n = 3x = 45) of Gladiolus tenuis M.Bieb. in a considerable part of its area of distribution. Initially, we recorded the presence of a large clone of G. tenuis to the east of the Volga River, as a result of isozyme analysis. We also used AFLP fingerprinting to genotype 55 samples from 10 populations of G. tenuis and one population of the closely related G. imbricutus L. This analysis revealed an extremely low genetic diversity in sterile triploid populations of G. tenuis and a rather high genetic diversity in fertile tetraploid populations (2n = 4x = 60) over most of the area of this species. Genetic distances between fertile and sterile populations of G. tenuis were similar to those between different species of gladioli. It appears that a single sterile genotype has spread vegetatively over 800 km, propagating by daughter corms. The study of the reproductive features of G. tenuis suggests that the cause of sterility may be self-incompatibility between individuals of the clone.

The cacao pathogen Moniliophthora roreri (Marasmiaceae) possesses biallelic A and B mating loci but reproduces clonally.

The cacao pathogen Moniliophthora roreri belongs to the mushroom-forming family Marasmiaceae, but it has never been observed to produce a fruiting body, which calls to question its capacity for sexual reproduction. In this study, we identified potential A (HD1 and HD2) and B (pheromone precursors and pheromone receptors) mating genes in M. roreri. A PCR-based method was subsequently devised to determine the mating type for a set of 47 isolates from across the geographic range of the fungus. We developed and generated an 11-marker microsatellite set and conducted association and linkage disequilibrium (standardized index of association, IA(s)) analyses. We also performed an ancestral reconstruction analysis to show that the ancestor of M. roreri is predicted to be heterothallic and tetrapolar, which together with sliding window analyses support that the A and B mating loci are likely unlinked and follow a tetrapolar organization within the genome. The A locus is composed of a pair of HD1 and HD2 genes, whereas the B locus consists of a paired pheromone precursor, Mr_Ph4, and receptor, STE3_Mr4. Two A and B alleles but only two mating types were identified. Association analyses divided isolates into two well-defined genetically distinct groups that correlate with their mating type; IA(s) values show high linkage disequilibrium as is expected in clonal reproduction. Interestingly, both mating types were found in South American isolates but only one mating type was found in Central American isolates, supporting a prior hypothesis of clonal dissemination throughout Central America after a single or very few introductions of the fungus from South America.

Potato cultivation system affects population structure of Phytophthora infestans

Abstract Phytophthora infestans is one of the most destructive potato pathogens. Many factors influence the population structure of P. infestans , including migration, climate and type of potato cultivation. Here, we analyse 365 P. infestans isolates collected from three regions of Poland over three years. We determined mating type, mitochondrial haplotype, resistance to metalaxyl, virulence and polymorphism at 14 simple sequence repeat (SSR) loci. Analysis of SSR markers showed high genetic diversity associated with this population. Model-based structure analysis grouped 299 unique genotypes into four main clusters. The P. infestans isolates collected from the Mlochow region, which has the most intensive level of potato cultivation, formed a distinct cluster, indicating a strong effect of the cultivation system on pathogen population structure. Three clusters contained isolates with frequent presence of three alleles at one locus, which may affect their capacity for sexual reproduction and preserve groups of fit genotypes that propagate asexually.

Origin, divergence, and phylogeny of asexual Epichloë endophyte in Elymus species from western China.

Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB) and translation elongation factor 1-α (tefA). Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents.

Assessment of somaclonal variation in somatic embryo-derived plants of yacon [Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson] using inter simple sequence repeat analysis and flow cytometry

article i nfo Background: Yacon (Smallanthus sonchifolius) is a root crop native to the Andean region. Low sexual reproductive capacity is a major constraint facing the genetic breeding of this crop. Biotechnological techniques offer alternative ways to widen genetic variability. We investigated somaclonal variation in regenerants of yacon derived from in vitro somatic embryogenesis using simple sequence repeat (ISSR) analysis and flow cytometry. Results: Twenty tested ISSR primers provided a total of 7848 bands in 60 in vitro regenerants and control plant. The number of bands for each primer varied from 3 to 10, and an average of 6.95 bands was obtained per ISSR primer. Eight primers were polymorphic and generated 10 polymorphic bands with 7.19% mean polymorphism. ISSR analysis revealed genetic variability in 6 plants under study. These regenerants had Jaccard's distances 0.104, 0.020, 0.040, 0.106, 0.163 and 0.040. Flow cytometric analysis did not reveal changes of relative nuclear DNA content in regenerants suggesting that the plants obtained via somatic embryogenesis had maintained stable octoploid levels. Conclusions: Our findings show that indirect somatic embryogenesis could be used in yacon improvement to widen genetic variability, especially when low sexual reproductive capacity hinders classical ways of breeding.