High Intrapopulation Research Articles

Morphological Traits and Phenolic Compounds in Tunisian Wild Populations and Cultivated Varieties of Portulaca oleracea L.

This study aims to evaluate the bio-morphological and biochemical variability of three Tunisian wild populations and one growing cultivar of purslane (Portulaca oleracea L.). The studied varieties should be easily distinguished by the color and the habitus of the plant as mentioned in literature, but the various analyses have shown a strong morphological heterogeneity within and among the wild and cultivated accessions as presented by the variance analysis test (ANOVA) and the PCA (Principal component analysis). We found high intrapopulation variability through the wild populations that make it hard to differentiate them only on the base of morphology. We analyzed the biochemical profile of those populations based on the analysis of freeze-dried samples of leaves and stems. We identified and quantified twelve different phenolic compounds by the HPLC-diode array detector (DAD) technique. Six phenolic acids and flavonoids were identified in the leaves and stems of the wild and cultivated populations. Sinapic acid and myricetin are the majors identified compounds through our samples. The results were significantly different in relation to the plant organs and to the geographic origin for most of the compounds. The obtained results highlighted the importance of Portulaca as a medicinal plant by showing its richness in phenols and flavonoids that have multi-medicinal effects besides their antioxidant power.

GENETIC DIVERSITY OF TULIPA SUAVEOLENS ROTH POPULATIONS IN VOLGOGRAD PROVINCE

Background. The current natural habitat of Tulipa suaveolens Roth rapidly decreases. In order to work out the strategy of the species’ preservation, evaluation of its intraand interpopulation polymorphism is required.Materials and methods. Molecular-genetic ISSR markers were used to analyze 125 samples from 10 populations of T. suaveolens occurring in Volgograd Province and 4 populations from Saratov Province.Results. ISSR analysis revealed high intrapopulation polymorphism (73–89%) in T. suaveolens populations form Volgograd Province. AMOVA attributed the largest proportion of variability (74.3%) to intrapopulation polymorphism. Interpopulation differences account for 25.7%. Total subdivision of populations (FST) was 0.257; total gene flow (Nm) between populations was 0.723. According to Bayesian analysis and clustering with both UPGMA and Neighbor Joining methods, all the studied T. suaveolens samples from Volgograd Province make up a large genetic group: within that group none of the potential subgroups may be associated with a particular place of collecting. The NewHybrids software was applied, and the results pointed to the hybrid nature of most samples. Samples of three populations from Saratov Province made up a separate genetic group; those samples fell under the category of parent forms.Conclusion. Considering that genetic subdivision of T. suaveolens populations within the administrative borders of Volgograd Province is insignificant, while all the province’s natural parks and a number of protected natural areas undertake measures to preserve the species, the existing conservation strategy may be recognized as effective and sufficient.

Isozyme structure of the Ixodes persulcatus Schulze (Acari: Ixodidae) tick populations in the Baikal Region

We have studied 13 enzyme systems encoded by 15 loci of the I. persulcatus tick populations from two suburban areas of the city of Irkutsk. We have identified a high intrapopulation heterogeneity and insignificant differences between the two populations. This indicates a high rate of gene migration.

Водоудерживающая способность хвои в популяциях основных лесообразующих видов хвойных в лесах таежной зоны Сибири

The limits of individual variation of trees by the water-retaining capacity of needles in populations of forest-forming coniferous species (Scots pine, Siberian pine, Siberian spruce and Siberian fir) growing in the conditions of the mountainous, middle and northern taiga of Central and Eastern Siberia were studied. It is found that among the compared evergreen species, Scots pine and Siberian pine are characterized by the highest intrapopulation variation in the rate of needles dehydration; Siberian spruce and Siberian fir are characterized by greater variability in the ability of needles to water absorption. However, in samples of the last twospecies, the share of trees with a low rate of water loss is quite large, even in wet habitats. In more drought-resistant pine species there is a smaller part of trees, which quickly evaporate moisture and have a high water capacity of needles. While a smaller part of trees of Siberian spruce and Siberian fir are less resistant to dehydration and differ by low water capacity of needles. While in Siberian spruce and Siberian fir a smaller part are trees less resistant to dehydration with low water capacity of needles. We revealed the significant differences between species in mixed stands and between geographic populations of species by water-retaining capacityof needles. The highest values of this indicator were obtained for Scots pine and Siberian spruce from Yakutia, as well as for old-growth trees of Siberian pine from the Western Sayan. The necessity of preserving old-growth stands and trees, characterized by the greatest drought resistance of needles, especially hygrophilous dark coniferous species in a changing climate is emphasized.The obtained data and correlations between the used features allow us to estimate one of the components of drought resistance of taiga populations of coniferous species and their intrapopulation diversity.For citation: Tikhonova N.А., Tikhonova I.V. Water Retaining Capacity of Needles in Populations of the Main Forest-Forming Coniferous Species in the Forests of the Taiga Zone of Siberia. Lesnoy Zhurnal [Forestry Journal], 2019, no. 5, pp. 83–94. DOI: 10.17238/issn0536-1036.2019.5.83Funding: The research is carried out within the framework of the budget project No. 0346-2016-0301 of the West-Siberian Branch of Sukachev Institute of Forest SB RAS and the Federal Research Center “Krasnoyarsk Science Center SB RAS” with the partial financial support from the Russian Foundation for Basic Research, the Government of Krasnoyarsk Territory, and the Krasnoyarsk Regional Fund of Science in the framework of the research project No. 18-44-240002.

Intrapopulation variability for male gametophyte traits in the tomato F<sub>3</sub> and F<sub>4</sub> offspring derived from high temperature resistant F<sub>2</sub> recombinants

Relevance Identification of forms resistant to thermal stress is important not only at the stage of search, but also later in the selection process. Methods The paper presents the results obtained during the studies on the variability of tomato male gametophyte traits (pollen viability, pollen tube length, pollen resistance and resistance along pollen tubes) in the hybrid F2, F3 and F4 offspring derived from different crossing combinations strongly resistant to high temperature stress (8 hybrid combinations). Results Recombination differences expressed in the values of average variation per family (S2) have been found in the F2 populations segregated for a complex of pollen traits, which made it possible to isolate transgressive recombinants from different hybrid combinations, to produce seeds from them and to further perform selection cycles in F3. It has been found that high intrapopulation variability of male gametophyte traits is preserved in F3 and F4 offspring, which reflects the response of their genotypes to high temperature. The offspring derived from the best F2 recombinants has been shown to not preserve a high level of resistance in F3 and F4. As for the pollen heat resistance, the actual shift of the trait values in F3 in relation to F2 made 0.92, while it made 0.65 in F4 in relation to F2. The shift of the values in the dynamics of the F2, F3 and F4 generations from different hybrid combinations was somewhat higher for the resistance of pollen tubes making 0.99 (F3/F2) and 1.15 (F4/F2). The most pronounced positive shift towards high values in F3 and F4 in relation to F2 was recorded just in three combinations, L7 x L305, L7 x cv. Ceros, L7 x cv. Lider (R – 1.91; 1.29 and 1.08, respectively). High variability in the populations of F4 offspring is observed for quantitative traits, as well, namely, inflorescence number per plant, flower number per inflorescence, the number of set fruits per inflorescence and seed number in fruits. The differences in the offspring diversity found during estimation of the segregating F2 populations derived from different crossing combinations for the variability range have not been confirmed in F3 and F4.

Novel Caudovirales associated with Marine Group I Thaumarchaeota assembled from metagenomes.

Marine Group I (MGI) Thaumarchaeota are some of the most abundant microorganisms in the deep ocean and responsible for much of the ammonia oxidation occurring in this environment. In this work, we present 35 sequences assembled from metagenomic samples of the first uncultivated Caudovirales viruses associated with Thaumarchaeota, which we designated marthavirus. Most of the sequences were obtained from cellular metagenomes confirming that they represent an important tool to study environmental viral communities due to cells retrieved while undergoing viral lysis. Metagenomic recruitment showed that this viral population is formed by very divergent entities with high intrapopulation homogeneity. However, metatranscriptomic analyses revealed the same differential expression profile with the capsid as major transcript, indicative of viruses during the lytic cycle. The cobalamine biosynthesis gene cobS, an auxiliary metabolic gene, was also highly expressed during the infection. These analyses expand our understanding of the global diversity of archaeal viruses.

Methylation divergence of invasive Ciona ascidians: Significant population structure and local environmental influence.

The geographical expansion of invasive species usually leads to temporary and/or permanent changes at multiple levels (genetics, epigenetics, gene expression, etc.) to acclimatize to abiotic and/or biotic stresses in novel environments. Epigenetic variation such as DNA methylation is often involved in response to diverse local environments, thus representing one crucial mechanism to promote invasion success. However, evidence is scant on the potential role of DNA methylation variation in rapid environmental response and invasion success during biological invasions. In particular, DNA methylation patterns and possible contributions of varied environmental factors to methylation differentiation have been largely unknown in many invaders, especially for invasive species in marine systems where extremely complex interactions exist between species and surrounding environments. Using the methylation‐sensitive amplification polymorphism (MSAP) technique, here we investigated population methylation structure at the genome level in two highly invasive model ascidians, Ciona robusta and C. intestinalis, collected from habitats with varied environmental factors such as temperature and salinity. We found high intrapopulation methylation diversity and significant population methylation differentiation in both species. Multiple analyses, such as variation partitioning analysis, showed that both genetic variation and environmental factors contributed to the observed DNA methylation variation. Further analyses found that 24 and 20 subepiloci were associated with temperature and/or salinity in C. robusta and C. intestinalis, respectively. All these results clearly showed significant methylation divergence among populations of both invasive ascidians, and varied local environmental factors, as well as genetic variation, were responsible for the observed DNA methylation patterns. The consistent findings in both species here suggest that DNA methylation, coupled with genetic variation, may facilitate local environmental adaptation during biological invasions, and DNA methylation variation molded by local environments may contribute to invasion success.

Inter- and intraspecific variability of selected diarylheptanoid compounds and leaf morphometric traits in Alnus glutinosa and Alnus incana

Abstract The reliability of diarylheptanoids as chemotaxonomic markers at inter- and intraspecific levels has been investigated. Six diarylheptanoids were quantified in bark ethanol extracts of four Alnus spp. populations by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The populations described here as locus classicus Alnus glutinosa (I) and locus classicus Alnus incana (III) are clearly differentiated. Compared to population I, individuals in population III have higher extract yields and hirsutanonol-5-O-β-D-glucopyranoside content and lower contents of hirsutanonol, rubranoside A and oregonin. Individuals from neighboring populations of A. glutinosa (II) and A. incana (IV) share similar contents of hirsutanonol. All the studied populations exhibit a high intrapopulation variability of the selected diarylheptanoids; they have a heterogeneous chemotype and they partially overlap. The geographical proximity of populations II and IV increases their chemical similarity. Principal component analysis (PCA) clearly shows that the biggest dispersion of individuals lies within population IV. The reason for its heterogeneity might be its physical proximity to population II, i.e. the appearance of hybrids. Also, geometric morphometrics of leaves was performed as a screening criterion for spontaneous hybrids.

The effects of genetic variation and environmental factors on rhynchophylline and isorhynchophylline in Uncaria macrophylla Wall. from different populations in China.

Uncaria macrophylla Wall. is an important Chinese medicinal herb. Rhynchophylline (RIN) and isorhynchophylline (IRN) are its major active compounds. We investigated the influence of genetic differentiation and environmental factors on the RIN and IRN to find the main influencing factors of their contents and lay the foundation for the following cultivation and breeding. We used inter-simple sequence repeat (ISSR) markers to investigate the genetic diversity, and high-performance liquid chromatography (HPLC) to measure the contents of RIN and IRN in 200 samples of U. macrophylla obtained from nine natural populations, and then to analyze the correlation between genetic differentiation, environmental factors of sampling sites and the contents of RIN and IRN. We found that High intra-population (80.05%) and low inter-population (19.95%) genetic diversity existed in the samples of U. macrophylla. To some extent, genetic differentiation and the contents of RIN and IRN had correlation in individual populations (such as JH, MH, XM, and ML). The RIN and IRN contents were significant negatively correlated with the precipitation in May (RIRN = -0.771, p = 0.015) and June (RRIN = -0.814, p = 0.008; RIRN = -0.921, p = 0.000), indicating that precipitation was the main affecting factor of their contents. Interestingly, the analysis results showed that the RIN content had a significant positive correlation (r = 0.585, p = 0.000) with the IRN content (they are isomers); the proportion of RIN had a significant negative correlation with the sum of the two (r = –0.390, p<0.0001), while the proportion of IRN had a significant positive correlation (r = 0.390, p<0.0001). It meant that, with the total quantity of the two compounds increased, the proportion of RIN decreased and the proportion of IRN increased, illustrating that their conversion exist some regularity. Moreover, the content ratio of RIN and IRN was significant positively correlated with the January precipitation (r = 0.716, p = 0.030), implying that January may be the key period for the mutual transformation of RIN and IRN.

Low genetic diversity contrasts with high phenotypic variability in heptaploid Spartina densiflora populations invading the Pacific coast of North America.

Species can respond to environmental pressures through genetic and epigenetic changes and through phenotypic plasticity, but few studies have evaluated the relationships between genetic differentiation and phenotypic plasticity of plant species along changing environmental conditions throughout wide latitudinal ranges. We studied inter‐ and intrapopulation genetic diversity (using simple sequence repeats and chloroplast DNA sequencing) and inter‐ and intrapopulation phenotypic variability of 33 plant traits (using field and common‐garden measurements) for five populations of the invasive cordgrass Spartina densiflora Brongn. along the Pacific coast of North America from San Francisco Bay to Vancouver Island. Studied populations showed very low genetic diversity, high levels of phenotypic variability when growing in contrasted environments and high intrapopulation phenotypic variability for many plant traits. This intrapopulation phenotypic variability was especially high, irrespective of environmental conditions, for those traits showing also high phenotypic plasticity. Within‐population variation represented 84% of the total genetic variation coinciding with certain individual plants keeping consistent responses for three plant traits (chlorophyll b and carotenoid contents, and dead shoot biomass) in the field and in common‐garden conditions. These populations have most likely undergone genetic bottleneck since their introduction from South America; multiple introductions are unknown but possible as the population from Vancouver Island was the most recent and one of the most genetically diverse. S. densiflora appears as a species that would not be very affected itself by climate change and sea‐level rise as it can disperse, establish, and acclimate to contrasted environments along wide latitudinal ranges.

Genetic structure of populations of Aphis gossypii (Hemiptera: Aphididae) on citrus trees in Northern Iran

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a serious pest of citrus in northern Iran, both because of the damaged caused by its feeding and as a vector of several viruses. The genetic structure of populations of A. gossypii on citrus trees at eight localities in Iran was surveyed using seven polymorphic microsatellite loci. Of 240 individuals tested, 142 multilocus genotypes (MLGs) were identified. The presence of multicopy genotypes and negative FIS values revealed that the major mode of reproduction in northern Iran is obligate parthenogenesis. The genotypic diversity of populations ranged between 0.24 and 0.93. Considerable genotypic diversity and a high frequency of unique MLGs, confirmed there is some cyclical parthenogenesis in the region. The analysis of molecular variance revealed high intrapopulation and weak interpopulation genetic differentiation (overall FST = 0.036) among the different populations. The UPGMA dendrogram of eight populations based on Nei's genetic distance indicated two clusters: genotypes from West of Mazandaran and Guilan provinces and those from East of Mazandaran. The same results were also obtained from the STRUCTURE analysis of these populations. This information on the genetic diversity of populations of A. gossypii in northern Iran could be useful for improving the Integrated Pest Management of this aphid.

ANALYSIS OF GENOTYPIC DIVERSITY PROVIDES A FIRST GLIMPSE ON THE PATTERNS OF SPREAD OF THE WOOD DECAY FUNGUS PERENNIPORIA FRAXINEA IN AN URBAN PARK IN NORTHERN ITALY

Perenniporia fraxinea is a fungal pathogen causing wood decay in roots and bole of a wide variety of broadleaf tree species. Despite its ecological importance, little is know about the infection biology of this fungus and in particular of its ability to infect trees through the mycelia growth through root contacts. To clarify its spreading mechanisms, a genetic analysis of 20 P. fraxinea isolates obtained from basidiomata collected from closely located Robinia pseudoacacia and Quercus robur trees in the Vernavola Urban Park (Pavia, Italy) and in surrounding areas was performed. Random Amplified Microsatellites (RAMs) fingerprinting was conducted allowing to distinguish 19 different haplotypes. High intrapopulation diversity was confirmed by somatic incompatibility tests (SITs), which were performed by dual- culturing isolates in vitro in all possible combinations, resulting in detection of 16 compatibility groups. These results, together with Non-metric MultiDimensional Scaling (NMDS) analysis on genetic data, suggest that spread through root contacts is unlikely for P. fraxinea. In addition, a significant negative correlation between spatial distribution and kinship coefficients was observed in isolates from the Vernavola Urban Park, suggesting a limited dispersal potential of P. fraxinea basidiospores. This report provides a first glimpse of the primary mechanisms of spread of P. fraxinea.

Evaluation of the Efficacy of Sex Pheromones and Food Attractants Used to Monitor and Control Synanthedon Myopaeformis (Lepidoptera: Sesiidae)

Synanthedon myopaeformis (Borkhausen, 1789) (Lepidoptera: Sesiidae) is a prominent pest of commercial apple orchards in Europe. the sex pheromones of S. myopaeformis and food attractants based on apple juice, beer and red wine were evaluated as tools for monitoring and control the populations of S. myopaeformis in apple orchards in the Czech Republic. For monitoring S. myopaeformis flight activity, trap designs were also evaluated, and the results indicated that wing traps were more suitable than delta traps because of their high efficacy even at low population densities of S. myopaeformis. The flight activity patterns of S. myopaeformis showed high intrapopulation variability and variability between years. The use of pheromones as a mating disruption technique led to a decrease of tree injury in comparison to untreated controls during the three years of the experiment. The reduction of the number of S. myopaeformis larvae per tree on a 14-ha plot treated subjected to the mating disruption technique reached 56 % in the third year of the experiment. In the three-year experiment using food attractants for the mass trapping of S. myopaeformis, catches of S. myopaeformis in traps using a combination of beer and apple juice (50:50) at a density of 4 traps/ha on a 4-ha plot increased more than 4-fold.

Genetic diversity of pacu and piapara broodstocks in restocking programs in the rivers Paraná and Paranapanema (Brazil)

The genetic diversity of Piaractus mesopotamicus (pacu) and Leporinus elongatus (piapara) broodstocks used in restocking programs in the rivers Paraná and Paranapanema is analyzed. One hundred and twenty specimens (two broodstocks of each species) from fish ponds in Palotina PR Brazil and in Salto Grande SP Brazil were assessed. Ten primers produced 96 fragments, comprising 68 (70.83%) and 94 (97.92%) polymorphic fragments for P. mesopotamicus and L. elongatus broodstocks, respectively. Differences (p &amp;lt; 0.05) in the frequency of 15 and 27 fragments were detected for each species, without exclusive fragments. Shannon Index (0.347 - 0.572) and the percentage of polymorphic fragments (57.3% - 94.8%) revealed high intra-population genetic variability for all broodstocks. Results of molecular variance analyses (AMOVA) showed that most variations do not lie between the broodstocks but within each broodstock (89%). Genetic (0.088 and 0.142) and identity (0.916 and 0.868) distance rates demonstrated similarity between the broodstocks of each species, corroborated by Fst (0.1023 and 010.27) and Nm (4.18 and 4.33) rates, with a slight genetic difference due to genic flux. High intrapopulation genetic variability and similarity between the broodstocks of each species was also detected, proving a common ancestry.

Testosterone and Haemosporidian Parasites Along a Tropical Elevational Gradient in Rufous-Collared Sparrows (Zonotrichia capensis).

Elevation has been proposed as a dominant ecological variable shaping life history traits and subsequently their underlying hormonal mechanisms. In an earlier meta-analysis of tropical birds, elevation was positively related to testosterone levels. Furthermore, parasitism by avian haemosporidians should vary with elevation as environmental conditions affect vector abundance, and while testosterone is needed for breeding, it is hypothesized to be immunosuppressive and thus could exacerbate haemosporidian infection. Our objective in this study was to examine the relationships between elevation, testosterone levels, and parasitism by avian haemosporidians. We surveyed breeding male rufous-collared sparrows (Zonotrichia capensis) across a wide elevational range along the equator. We measured baseline testosterone levels, haemosporidian infection at four elevations spanning the species' natural range in the Ecuadorian Andes (600, 1500, 2100, 3300 m). Testosterone levels from breeding males were not related to elevation, but there was high intrapopulation variability. Testosterone levels were not related to the probability of parasitism, but our results from one population suggested that the likelihood of being infected by haemosporidian parasites was greater when in breeding condition. In conclusion, even though there is variation in life history strategies among the studied populations, wider divergence in seasonality and life history traits would probably be needed to detect an effect of elevation on testosterone if one exists. Additionally, our results show that variation in testosterone is not related to infection risk of haemosporidians, thus other factors that take a toll on energetic resources, such as reproduction, should be looked at more closely.

Challenges in the analysis of viral metagenomes.

Genome sequencing technologies continue to develop with remarkable pace, yet analytical approaches for reconstructing and classifying viral genomes from mixed samples remain limited in their performance and usability. Existing solutions generally target expert users and often have unclear scope, making it challenging to critically evaluate their performance. There is a growing need for intuitive analytical tooling for researchers lacking specialist computing expertise and that is applicable in diverse experimental circumstances. Notable technical challenges have impeded progress; for example, fragments of viral genomes are typically orders of magnitude less abundant than those of host, bacteria, and/or other organisms in clinical and environmental metagenomes; observed viral genomes often deviate considerably from reference genomes demanding use of exhaustive alignment approaches; high intrapopulation viral diversity can lead to ambiguous sequence reconstruction; and finally, the relatively few documented viral reference genomes compared to the estimated number of distinct viral taxa renders classification problematic. Various software tools have been developed to accommodate the unique challenges and use cases associated with characterizing viral sequences; however, the quality of these tools varies, and their use often necessitates computing expertise or access to powerful computers, thus limiting their usefulness to many researchers. In this review, we consider the general and application-specific challenges posed by viral sequencing and analysis, outline the landscape of available tools and methodologies, and propose ways of overcoming the current barriers to effective analysis.

Patterns of morphological variation among populations of the widespread annual killifish Nothobranchius orthonotus are independent of genetic divergence and biogeography

Populations of annual killifish of the genus Nothobranchius occur in patchily distributed temporary pools in the East African savannah. Their fragmented distribution and low dispersal ability result in highly structured genetic clustering of their populations. In this study, we examined body shape variation in a widely distributed species, Nothobranchius orthonotus with known phylogeographic structure. We tested whether genetic divergence of major mitochondrial lineages forming two candidate species is congruent with phenotypic diversification, using linear and geometric morphometry analyses of body shape in 23 wild populations. We also conducted a common-garden experiment with two wild-derived populations to control for the effect of local environmental conditions on body shape. We identified different allometric trajectories for different mitochondrial lineages and candidate species in both sexes. However, in a principal components analysis of population-level body shape, the separation among mitochondrial lineages was incomplete. Higher similarity of mitochondrial lineages belonging to different candidate species than that of same candidate species prevented distinction of the two candidate species on the basis of body shape. Analysis at the individual level demonstrated that N. orthonotus express high intrapopulation variability, with major overlap among individuals from all populations. In conclusion, we suggest that N. orthonotus be considered as a single species with an extensive geographic range, strong population genetic structure and high morphological variability.

Stable isotope evaluation of population‐ and individual‐level diet variability in a large, oligotrophic lake with non‐native lake trout

AbstractNon‐native piscivores can alter food web dynamics; therefore, evaluating interspecific relationships is vital for conservation and management of ecosystems with introduced fishes. Priest Lake, Idaho, supports a number of introduced species, including lake trout Salvelinus namaycush, brook trout S. fontinalis and opossum shrimp Mysis diluviana. In this study, we used stable isotopes (δ13C and δ15N) to describe the food web structure of Priest Lake and to test hypotheses about apparent patterns in lake trout growth. We found that isotopic niches of species using pelagic‐origin carbon did not overlap with those using more littoral‐origin carbon. Species using more littoral‐origin carbon, such as brook trout and westslope cutthroat trout Oncorhynchus clarki lewisi, exhibited a high degree of isotopic niche overlap and high intrapopulation variability in resource use. Although we hypothesised that lake trout would experience an ontogenetic diet shift, no such patterns were apparent in isotopic signatures. Lake trout growth rates were not associated with patterns in δ15N, indicating that variation in adult body composition may not be related to adult diet. Understanding trophic relationships at both the individual and species levels provides a more complete understanding of food webs altered by non‐native species.

Genetic differentiation and recombination among geographic populations of the fungal pathogen Colletotrichum truncatum from chili peppers in China.

Colletotrichum truncatum is an extremely important fungal pathogen. It can cause diseases both in humans and in over 460 plant species. However, little is known about its genetic diversity within and among populations. One of the major plant hosts of C. truncatum is pepper, and China is one of the main pepper-producing countries in the world. Here, we propose the hypotheses that geography has a major influence on the relationships among populations of C. truncatum in China and that infections in different populations need to be managed differently. To test these hypotheses, we obtained and analyzed 266 C. truncatum isolates from 13 regions representing the main pepper-growing areas throughout China. The analysis based on nine microsatellite markers identified high intrapopulation genetic diversity, evidence of sexual recombination, and geographic differentiation. The genetic differentiation was positively correlated with geographic distance, with the southern and northern China populations grouped in two distinct clusters. Interestingly, isolates collected from the pepper-breeding center harbored the most private alleles. The results suggest that the geographic populations of C. truncatum on peppers in China are genetically differentiated and should be managed accordingly. Our study also provides a solid foundation from which to further explore the global genetic epidemiology of C. truncatum in both plants and humans.

Phenotypic variability in a population of globe artichoke

The existence of variability is a prerequisite for genetic improvement in plants. Globe artichoke is a high nutritious vegetable with medical value, representing a profitable alternative for rural producers. This research was conducted with the aim of evaluating the phenotypic variability in a commercial cultivar of artichoke (Cynara cardunculus var. scolymus L) established from seeds. Field plants were assessed when primary head reached commercial stage. An amount of 21 quantitative and 5 multicategoric characters were assessed. The quantitative data were submitted to multivariate analysis. For quantitative characters the distance between individuals varied from 3.0 to 50.9, revealing high intrapopulation variability. The greater relative contribution characters for genetic divergence were the primary head fresh mass (79.88%) and bottom fresh mass (8.43%). This indicates the possibility of plant selection for head quality in this population. The clustering analysis through UPGMA method, based on quantitative characters, allowed the formation of five groups. For multicategoric traits, the similarity among individuals varied from 1.22% to 100%. Within the existing population variability, it was possible to select plants with superior quantitative traits desirable for in natura consumption, as primary head fresh weight and length, bottom fresh mass, bract basis length and width, as well as non-quantitative traits as round head shape, absence of thorn and presence of violet color in the head.