Genetic structure and diversity of India hybrid tea

The most important evolutionary event in the success of commercial tea cultivation outside China in ~30 countries came about by the origin of India hybrid tea in India, derived from the extensive spontaneous hybridization that took place between the Assam type tea growing in the forest regions of Assam, North-East India and China type tea introduced from China in ~1875 to many regions of North-East India. The release of an enormous pool of vigorous and highly variable plants of India hybrid tea in North-East India was a significant step forward for the origin and evolution of tea as a highly successful crop plant. The 1,644 accessions and clones of India hybrid tea, representatives of known 15 morphotypes, were screened by 412 AFLP markers amplified by 7 AFLP primer pair combinations. All the 412 genetic loci were polymorphic across the 1,644 accessions and clones. The analysis was done with distance (PCoA and NJ) methods, and the STRUCTURE (Bayesian) model. Both PCoA and NJ analysis clustered 1,644 tea accessions and clones into six major groups with one group in each, constituted mostly by China hybrid, Assam China hybrid and Assam hybrid morphotypes, of distinct genetic identity. No group was exclusive for any particular morphotype. The accessions and clones belonging to morphotypes, Assam type, Assam hybrid, China hybrid and China Cambod were distributed in all the groups. It is the Assam type/Assam hybrid morphotypes which exhibit much broader genetic variability than in China type/China hybrid/Cambod type/Cambod hybrid morphotypes. The STRUCTURE analysis inferred 16 populations (K = 16), for which the greatest values of probability were obtained. Nine of the 16 clusters were constituted by the tea accessions and clones of ‘pure’ ancestry. The remaining clusters were of ‘mixed’ ancestry. This analysis provides evidence that the accessions and clones of the same morphotype are not always of same genetic ancestry structure. The tea accessions and clones obtained from outside North-East India shared the same groups (distance method) and clusters (STRUCTURE model) which were constituted by North-East India accessions. The present study also demonstrates very narrow genetic diversity in the commercial tea clones vis-à-vis the profound genetic diversity existing in the tea accessions. These clones were distributed in hardly two of the six groups in NJ tree. The identified 105 core accessions and clones, capturing 98% diversity, have their origin from almost all groups/subgroups of NJ tree.     

Genetic diversity and species delimitation in the cultivated and wild Guinea yams (Dioscorea spp.) from Southwest Ethiopia as determined by AFLP (amplified fragment length polymorphism) markers

Yams (Dioscorea spp.) rank as the fourth most important root and tuber crop after potatoes, cassava and sweet potatoes. They are an economic crop in most of the tropics especially in West Africa, which produces over 95 % of the world output. Despite their cultural and economic importance there is taxonomic confusion regarding Guinea yams. The currently used classification scheme, which relies on vegetative and inflorescence characters, does not consistently delimit species boundaries between members of Guinea yams (D. cayenensis Lam.–D. rotundata Poir. complex), their wild relatives (D. abyssinica Kunth and D. praehensilis Benth.,) and D. sagittifolia Pax. Establishing the taxonomic identity of the germplasm and understanding the systematic relationships among crops is vital to the management of genetic resources and the utilization of accessions. In this study, amplified fragment length polymorphism (AFLP) genetic fingerprinting was used to evaluate and characterize 43 individual plants, belonging to different populations of wild and cultivated Guinea yams. The three primer combinations used in the AFLP analyses generated 158 scorable bands, with an overall polymorphism of 78 %. Ordination and cluster analyses of AFLP data failed to produce any clear species boundary between either the Guinea yam accessions or between them and their wild relatives. The average genetic similarity between the study individuals of Guinea yams and their wild relatives ranged from 60 to 100 %. The first, second and third principal coordinates axes cumulatively account for 77.45 % of the total variation. AFLP analyses also revealed a higher genetic divergence among cultivated Guinea yam accessions of the Sheko cultivars. Ordination and cluster analysis using UPGMA revealed no clear species boundaries between members of the complex. Thus, the taxonomy of these “species” needs to be revisited using other markers.     

Chromatographic fingerprinting of <Emphasis Type="Italic">Lupinus luteus</Emphasis> L. (Leguminosae) main secondary metabolites: a case of domestication affecting crop variability

Secondary metabolites (SMs), such as alkaloids and raffinose oligosaccharides (RFOs), play important roles in plant physiology. Although alkaloid and RFO phenotypic variation has been reported for yellow lupin (Lupinus luteus L.), most evaluations have used a reduced number of accessions; thus, limiting the understanding of accumulation patterns and variation ranges. The main goal of this research was to assess alkaloid and RFO content in a diverse L. luteus sample to understand possible SM accumulation patterns across this legume species. Eighteen yellow lupin accessions were analyzed using high performance thin layer chromatography to provide insights on seed and leaf RFO and alkaloid phenotypic variation. Co-dominant markers (170) were used to examine genetic relationships among L. luteus accessions and possible accumulation patterns across closely related genotypes. Significant differences were observed for seed and leaf RFOs. Total seed RFO accumulation ranged from 79.738 to 131.079 mg g^?1. Raffinose, stachyose, and verbascose were observed in all genotypes’ seeds, but at different RFO concentrations. Raffinose was the only RFO detected in leaves (2.793–0.4224 mg g^?1). Total alkaloid accumulation ranged from 0.22 to 15.12 and 0.00 to 8.007 mg g^?1 for seeds and leaves, respectively. Lupinine, sparteine, and gramine were observed in seeds and leaves, and showed a wide range of variation. Neighbor-Joining (NJ) analysis showed an apparent pattern of seed alkaloid accumulation, most likely due to domestication events. However, high RFO accumulating accessions were scattered across the NJ tree. Alkaloid and RFO significant phenotypic variation will not only help to understand the roles of these SMs in L. luteus, but also to uncover the genetic basis behind their accumulation.     

Exploring genetic diversity and disease response of cultivated rice accessions (<Emphasis Type="Italic">Oryza</Emphasis> spp.) against <Emphasis Type="Italic">Pyricularia oryzae</Emphasis> under rainfed upland conditions in Benin

The main goal of this study is to gain insight into the relationship between the genetic profile of cultivated rice (Oryza spp.) accessions and their resistance to rice blast. Therefore, the genetic and phenotypic variability of a set of 350 cultivated rice accessions originating from Africa (Benin, Mali and Nigeria, Ivory Coast etc.) was examined. Seventy-seven fluorescent amplified fragment polymorphism (AFLP) markers were used to gain insight into the genetic variation and to classify the germplasm collection. In addition, the rice germplasm was assessed for its resistance to blast disease caused by Pyricularia oryzae in upland field conditions. Huge differences in responses of rice accessions to P. oryzae were observed, ranging from highly susceptible to highly resistant. Twelve percent of all accessions were highly resistant to P. oryzae. Based on their AFLP marker profile these highly resistant accessions could be separated from the other accessions. Stepwise regression revealed that the best prediction of the blast resistance level was achieved with a maximum number of 13 AFLP markers. Marker CTA22 was the most important for accurate prediction of blast resistance, this marker was present in all highly resistant accessions. It can be concluded that AFLP markers are a valuable tool to screen rice accessions for their susceptibility towards blast disease and that, based on a subset of markers, it is possible to predict the resistance to rice blast.     

Identification of intra-accession genetic diversity in selfing crops using AFLP markers: implications for collection management

Germplasm conserved as seeds in genebanks requires regular regeneration. In this process, selection and genetic drift may cause loss of genetic diversity from accessions. In the case of selfing crops, separation of distinct lines into different accessions may be an efficient strategy to avoid these negative effects. In order to evaluate the applicability of this method for collection management, knowledge about the level of intra-accession genetic diversity is required. By means of AFLP analysis intra-accession variation was investigated in two cultivars, two landraces and two wild populations of ex situ conserved barley germplasm. In the total sample of 216 individuals analysed (36 per accession), 22 genotypes were observed based on 104 polymorphic loci. The number of genotypes detected ranged from 1 to 3 per accession, except for a Nepalese landrace that revealed 12 genotypes. An UPGMA cluster analysis grouped the genotypes unambiguously into the accession they belonged to and genotypes within accessions were generally found to be closely related. In order to determine the repeatability of the results obtained, 11 individuals belonging to 4 genotypes from the Nepalese landrace were scored for a second set of AFLP markers. Matrices of genetic distances calculated for the two AFLP datasets were found to be highly correlated (r = 0.9346, P < 0.001). Separation of genotypes into different accessions was considered a relevant option only for the Nepalese landrace. Analysis of molecular variance indicated that this accession could be well divided into 8 distinct lines. Further implications of the results for genebank practices are discussed.     

Genetic diversity in populations of the medicinal plant <Emphasis Type="Italic">Leonurus cardiaca</Emphasis> L. revealed by inter-primer binding site (iPBS) markers

Motherwort (Leonurus cardiaca L.) is a medicinal plant indigenous to the Mediterranean regions in Europe and Asia. The objective of this study is to apply inter-primer binding site (iPBS) markers to assess the molecular variation and genetic relationships of 89 genotypes of motherwort to assist the genetic improvement of this species. The genotypes comprised 79 from Iran and 10 collected in Australia and 15 additional accessions of two related species (L. heterophyllus Sweet and L. sibiricus L.) collected in Australia, were also included. PCR of 7 iPBS primers (dominant markers) produced a total of 191 bands ranging from 180 to 4000 bp and the mean PIC for primers ranged from 0.2213 to 0.3206 with a mean value 0.2921. The mean expected heterozygosity (0.134), the mean unbiased expected heterozygosity (0.140) and Shannon’s information index (0.213) indicated a high level of inbreeding among the accessions tested. Ordination and cluster analysis showed that the genetic relationships among all accessions could be separated into three major groups—L. cardiaca, L. heterophyllus and L. sibiricus. However, among the 89 accessions of L. cardiaca, genotypes collected from the same geographic region tended to cluster together thus indicating greater genetic similarity. The Motherwort accessions originating in Iran are highly divergent and possess abundant genetic diversity and clearly provide a basis for selection and breeding. The iPBS PCR-based genome fingerprinting technology used in this study is low-cost and effective in differentiating accessions of motherwort and their related species.     

Water yam (Dioscorea alata L.) diversity pattern in Brazil: an analysis with SSR and morphological markers

Substantial progress was made in the last decade in understanding the diversity in Dioscorea species. However, most of the studies so far concentrated in the ‘yam belt in Africa’. We present a genetic diversity and structure analysis among commercial and local varieties of water yam (Dioscorea alata L.) in Brazil using microsatellite and morphological markers. Twelve microsatellite primers were used to generate DNA profiles of 72 local varieties and 17 commercial accessions of water yam collected in four different regions in Brazil. Also, four morphological traits were evaluated on individual plants under field conditions. The morphological characterization showed considerable diversity. High polymorphism was found with 100 % polymorphism observed for 11 primers and a discriminating power value of 0.92, on average. We did not observe a strong population structure among sampling regions, while most of the genetic diversity was concentrated within regions (95.9 %). Analysis of the relationship between accessions did not clearly separate the local and commercial genotypes. However, the molecular analyses of D. alata showed high intraspecific diversity in local accessions from different regions in Brazil, with the highest Shannon index value (H′ = 0.41) for the Southeast region. These results confirmed an admixture of accessions in all sampling regions, consistent with the lack of a significant correlation between geographic and genetic distances, suggesting that farmers exchanged water yam materials extensively. The genetic diversity can be explained by the result of a continuous exchange of accessions by farmers throughout Brazil.     

Evaluation of seed yield and seed yield components in red–yellow (Pisum fulvum) and Ethiopian (Pisum abyssinicum) peas

Red–yellow (Pisum fulvum Sibth. et Sm.) and Ethiopian (Pisum abyssinicum A. Br.) peas have become of increasing interest to breeders in the last decade, as they have been found to be partially or completely tolerant to various biotic stresses, such as to attack by pea weevil, mildew blight or rust. A trial was carried out at the Institute of Field and Vegetable Crops at Rimski ?an?evi from 2005 to 2007, with 13 accessions each of red–yellow and Ethiopian peas sown at 100 viable seeds m^?2, in plots of 0.5 m². Seed yield per plant in red–yellow pea was significantly and positively correlated with seed number per plant (r = 0.881**), pod number per plant (r = 0.839**) and number of fertile nodes (r = 0.820**). The highest positive correlation among the agronomic characteristics in Ethiopian pea was between number of fertile nodes and number of pods (r = 0.937**). Seed yield in Ethiopian pea was highly significantly correlated with number of seeds (r = 0.807**), pods (r = 0.692*), and fertile nodes (r = 0.638*). The results suggest that plant morphology of the progenies between red–yellow or Ethiopian peas and grain-type common pea could not differ significantly from that of individual parents. That means that it could be possible to develop hybrid lines that could keep the desirable morphological traits of grain-type common pea, such as lodging-tolerance and high seed yields, and to make an introgression of a specific resistance from wild pea taxa, especially by back-crosses with the former. However, one must always be aware of unpredicted outcomes as a result of rather different genetic basis of individual seed yield components.     

Microsatellite mapping of the genes for sham ramification and extra glume in spikelets of tetraploid wheat

The loci for expression of prolonged spikelet rachilla named ‘sham ramification’ in three tetraploid wheat accessions, two accessions of Triticum jakubzineri Udacz. et Schachm. (2n = 4× = 28, genome BBAA) ‘PI 585014’ and ‘R-101-03’ and one sample of Triticum turgidum L. (2n = 4× = 28, genome BBAA) ‘PI 67339’, were mapped by genotyping F₂ populations using microsatellite markers. The segregation analysis confirmed that sham ramification was controlled by recessive, epistatic genes, shr1 (sham ramification 1) and shr2 (sham ramification 2). The genotypes of ‘sham ramification’ were shr1shr1Shr2Shr2 for T. jakubzineri and Shr1Shr1shr2shr2 for T. turgidum (PI 67339). Normal rachilla was determined by Shr1Shr1Shr2Shr2. The shr1 gene and the gene for extra glume (exg) were completely linked; and, the shr1/exg gene complex was bracketed by the markers Xbarc319 and Xbarc232 on the long arm of chromosome 5A. In the F₂ of PI 67339/LD222 the gene shr2 was bracketed by Xwmc819 and Xwmc794 on the long arm of chromosome 2A.     

Genetic variation and phylogenetic relationships among Indian Citrus taxa revealed by DAMD-PCR markers

Genetic variation and phylogenetic relationships among 50 wild and cultivated accessions of 19 Indian Citrus genotypes were examined through comparison of Directed Amplification of Minisatellite DNA (DAMD) markers and morphological characters. DAMD-PCR analysis with four primers resulted in amplification of a total of 45 bands, of which 35 (78 %) were polymorphic. Morphometric evaluation using 76 morphological characters showed high level of variability ranging from 0.18 to 1.00 (avg 0.39), whereas the Jaccard’s coefficient values of genetic similarity calculated from DAMD data ranged from 0.41 to 1.00 (avg 0.68), indicating moderate genetic divergence among the accessions studied. UPGMA dendrograms generated separately from morphometric and DAMD data segregated all the accessions of Citrus into four main clusters, each containing a true basic species and their probable hybrids. The grouping of individual accessions/genotypes under respective species or cultivars in DAMD dendrogram was based purely on their genetic relationships rather than geographical origin. There was no absolute congruence between the data and dendrograms generated from morphometric and DAMD analyses. The study demonstrates the resolving power of DAMD markers for discrimination of individual genotypes of Citrus under its respective species, hybrid or cultivar groups and inferring their genetic and phylogenetic relationships as well. This is the first report on application of DAMD markers in Citrus.     

Evaluation of genetic diversity in a Camelina sativa (L.) Crantz collection using microsatellite markers and biochemical traits

A genomic DNA library enriched with GA/TC repeats from Camelina sativa variety Calena has been analysed. After sequencing of about 200 randomly selected clones, approximately 60 % of them showed to contain simple or compound microsatellites with a high number of repeats. Among all microsatellite markers analysed 15 primer pairs amplified polymorphic fragments. Forty C. sativa accessions of different origin were genotyped with 15 microsatellite markers that generated 134 alleles with an average of 8.93 alleles per locus. The observed heterozygosity (Ho) among the accessions ranged from 0.0 to 0.15 with an average of 0.0370, whereas the average of expected heterozygosity (He) among accessions was 0.2769. The analysis of the average total heterozygosity (H_T = 0.651), the intrapopulation genetic diversity (H_S = 0.260), the interpopulation genetic diversity (D_ST = 0.391) and the coefficient of genetic differentiation among populations (G_ST = 0.574) demonstrated that 57.4 % of the genetic diversity is among the accessions, while 42.6 % resides within them. Phylogenetic tree of the 40 C. sativa accessions was constructed based on Nei’s genetic distance. The unweighted pair group method with arithmetic mean (UPGMA) dendrogram shows, except for CAM108 and CAM170, a clear discrimination among C. sativa accessions grouping them in five subgroups. ANOVA analysis indicates significant differences in some biochemical and agronomic parameters among the C. sativa accessions grouped according to Nei’s genetic distance. The result of the Tukey HSD test demonstrated that the A4 subgroup showed a significant higher TWS and linoleic acid (LA) content, while the subgroup A1 showed a significant higher linolenic and lower LA content compared to the remaining groups.     

Assessment of molecular diversity and population structure of the Ethiopian sorghum [Sorghum bicolor (L.) Moench] germplasm collection maintained by the USDA–ARS National Plant Germplasm System using SSR markers

The molecular diversity and population structure present in the Ethiopian sorghum collection maintained at the USDA–ARS National Plant Germplasm System (NPGS) has not been studied. In addition, 83 % of the accessions in the Ethiopian collection lack passport information which has constrained their evaluation and utility. Therefore, 137 Ethiopian accessions from NPGS were randomly selected and characterized with 20 strategically selected simple sequence repeat markers. These markers indentified 289 alleles with average polymorphic information content of 0.78. The allele frequency distribution reflects that 62 % of the alleles were rare (<0.05), 17 % range from 0.05 to 0.10, and 22 % were higher than 0.10. Expected and observed heterozygosity were estimated at 0.78 and 0.23, respectively, demonstrating Ethiopia has high sorghum genetic diversity germplasm. Population structure analysis indentified two subpopulations of 77 and 41 accessions, respectively, while a third group was constituted by 19 accessions whose classifications were not defined (i.e. hybrids). Analysis of molecular variances determined variation within subpopulations as the major source of variation. Likewise, genetic differentiation between subpopulations was moderate (F_st = 0.10). These results indicated that a continuous exchange of genes between subpopulations of sorghum exists in Ethiopia. The absence of a well defined population structure positioned this germplasm as an important resource for the study and dissection of agricultural traits by association mapping. However, genetic redundancy analysis indicated the presence of highly related accessions, therefore, strategic selected accessions must be consider prior to phenotype evaluation of larger number of accessions. The Ethiopian collection is composed of highly genetically diverse germplasm, and the genetic information presented herein is valuable to ex situ and in situ conservation programs to promote the use of this germplasm for breeding programs.     

Phenotypic and genetic characterization of Kyrgyz fine-leaved Festuca valesiaca germplasm for use in semi-arid,low-maintenance turf applications

Fine-leaved Festuca valesiaca Schleich. ex Gaudin (2n = 2x–4x) is native to heavily-grazed, cold, semi-arid, Asian rangelands. However, its potential for low-maintenance turf applications in the semi-arid western United States and its relatedness to other agriculturally important Festuca species have not been investigated. Therefore, a project was designed to identify F. valesiaca accessions that possess horticultural potential when grown under semi-arid growing conditions and to characterize their relatedness to other Festuca species. In 2008, 12 F. valesiaca accessions originating from Kyrgyzstan and eight US. Festuca and one Lolium cultivar were transplanted as replicated, spaced plants to a field nursery at Blue Creek, Utah. Relative vigor, height, width, total biomass (aboveground dry matter yield), seed weight, and seed number were evaluated between 2009 and 2011. Plant height, width, and total biomass of the F. valesiaca accessions examined were approximately equal to the commercial control, ‘Cascade’ (F. rubra L. subsp. commutata Gaudin; 6x; chewings fescue). Plant vigor and seed weight of F. valesiaca accessions PI 659923, PI 659932, W6 30575, and W6 30588 under semi-arid conditions (~300 mm annual precipitation) were significantly (P < 0.05) greater than ‘Cascade’. Moreover, principal component analysis based on all traits as loading factors indicated that these 12 F. valesiaca accessions were distinct from a majority of the other Festuca accessions examined. These F. valesiaca accessions produced abundant amounts of small seed, and this seed yield was significantly correlated with total aboveground biomass (dry weight; r ²  = 0.84, P < 0.001), plant height (r ²  = 0.58, P < 0.05), and plant vigor (r ²  = 0.83, P < 0.001). Amplified fragment length polymorphism (AFLP) analysis (1,454 polymorphic bands) was used to characterize F. valesiaca relatedness to other economically important Festuca species. The AFLP-based, neighbor-joining analysis differentiated F. valesiaca accessions from US Festuca cultivars examined, except for ‘Durar’ (F. ovina L.; 6x; sheep fescue), to which they had strong genetic affinities. Given their morphological attributes, F. valesiaca PI 659923, W6 30575, PI 659932, and W6 30588 should be considered for use in low-maintenance, semi-arid turf improvement programs in the western US.     

Genetic diversity and relationships of wild and cultivated <Emphasis Type="Italic">Zanthoxylum</Emphasis> germplasms based on sequence-related amplified polymorphism (SRAP) markers

The genus Zanthoxylum, belonging to Rutaceae, has a long history of cultivation both for economic and chemical values in China. To effectively conserve and sustainably utilize this genus resource, a study on genetic diversity and relationships of Zanthoxylum germplasms was carried out by employing SRAP markers. We used 16 primer combinations to assess genetic variations and relationships among 175 accessions from eight cultivated provenances, including Shandong, Henan, Shanxi, Shaanxi, Gansu, Sichuan, Guizhou and Yunnan. A total of 145 clear repetitive and intense bands were yielded, and the percentage of polymorphic bands was 100 % for per primer combination, indicating a relatively high diversity among Zanthoxylum germplasms. From a geographic perspective, the highest genetic diversity level was observed within Guizhou provenance (N _a  = 1.97, Ne = 1.52, H = 0.31, I = 0.46) while Henan provenance had the lowest genetic diversity (N _a  = 1.68, Ne = 1.45, H = 0.25, I = 0.37). Based on AMOVA results, the abundant genetic variation was mainly caused by variation of intra-provenances (84.96 %), rather than among provenances (15.038 %). The results indicated low genetic differentiation (G _st  = 0.133) and high gene flow (N _m  = 3.2605) among provenances. The neighbor-joining tree revealed that the 175 accessions could be divided into four groups, and groupings indicated a divergence between the cultivated accessions of Zanthoxylum bungeanum Maxim. and Z. armatum DC. Moreover, three accessions of Z. piperitum DC. var. inerme without prickles introduced from Japan gathered one cluster. Cluster IV is composed of accessions of different geographical origin, including 11 wild species and 10 cultivated accessions of Z. bungeanum. The cluster analysis also reflected a relatively close relationship between the geographical origins and the classification of accessions in cluster I. Structure analysis indicated that collected Zanthoxylum accessions could be divided into two major groups. The information obtained from our research would benefit to make use of Zanthoxylum germplasms and assist the management of a Zanthoxylum germplasms collection.     

Allelic diversity of high molecular weight glutenin subunits (HMW-GS) in Iranian Aegilops tauschii Coss. accessions by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE)

Variation of high molecular weight glutenin subunits (HMW-GS) in 28 Iranian Aegilops tauschii (2n = 2x = 14, DD) accessions studied by sodium dodecyl sulphate electrophoresis method (SDS-PAGE). The results showed high variation of HMW-GS in the accessions. The range of frequency in 14 HMW-GS combinations was 3.57–25 % in the accessions. AMOVA showed the molecular variance between the geographic areas was lower than within the geographic areas. According to Nei’s genetic diversity, the highest diversity levels were in Semnan, Golestan and Azarbayjan, on the other hand the lowest levels of diversity were found in Khorasan, Gilan and Mazandaran accessions. Hence, the Caspian Sea South East accessions also Azerbayjan in Iran have more diversity. AMOVA did not show variance between strangulata and tauschii but there was more genetic diversity in ssp. tauschii subspecies in comparison of ssp. strangulata according to Nei’s gene diversity and Shannon information index. It showed Iranian Ae. tauschii have a good potential for bread making quality improvement in bread wheat.     

Genetic variation for phenolic acids concentration and composition in a tetraploid wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L.) collection

Phenolic acid intake through the consumption of whole-wheat foods provides important health benefits associated with reduced risks of cardiovascular diseases and colon cancer. The genetic variation for phenolic acids was extensively studied in common wheat, but a comprehensive survey in tetraploid wheat is lacking. In this study we evaluated the genetic variability for individual and total phenolic acids concentration existing in a large collection of tetraploid wheat (Triticum turgidum L.). A 2-year evaluation was undertaken on the whole-meal flour of 111 genotypes belonging to seven T. turgidum subspecies including cultivars, landraces and wild accessions. Durum cultivars [T. turgidum subsp. durum (Desf.) MacKey], had the highest average concentration of total phenolic acids (828.7 μg g^?1 dm in 2012; 834.5 μg g^?1 dm in 2013) with amounts varying from 550.9 μg g^?1 dm to 1701.2 μg g^?1 dm, indicating a variation of greater than threefold fold. The lowest concentration of phenolic acids was found in T. turgidum subsp. dicoccum (Schrank ex Schübler) Thell. Rivet wheat (T. turgidum L. subsp. turgidum) had phenolic acid concentrations similar to those in durum, but less variation was noted among the accessions. On the other hand, the accessions of the four remaining subspecies showed lower phenolic acid concentrations and variation among the accessions as compared to durum. A total of six phenolic acids were identified across the wheat genotypes. The effects of genotype, year and year × genotype were estimated by ANOVA and resulted significant for all phenolic acids. The ratio of genotypic variance to total variance suggested the possibility of improving phenolic acid content in elite wheat germplasm through appropriate breeding programs. Moreover, significant correlations between phenolic acids and other quality characteristics of the grain were detected.     

Spatially structured genetic diversity of the Amerindian yam (Dioscorea trifida L.) assessed by SSR and ISSR markers in Southern Brazil

Dioscorea trifida L. (Dioscoreaceae) is among the economically most important cultivated Amerindian yam species, whose origin and domestication are still unresolved issues. In order to estimate the genetic diversity maintained by traditional farmers in Brazil, 53 accessions of D. trifida from 11 municipalities in the states of São Paulo, Santa Catarina, Mato Grosso and Amazonas were characterized on the basis of eight Simple Sequence Repeats (SSR) and 16 Inter Simple Sequence Repeats (ISSR) markers. The level of polymorphism among the accessions was high, 95 % for SSR and 75.8 % for ISSR. The SSR marker showed higher discrimination power among accessions compared to ISSR, with D parameter values of 0.79 and 0.44, respectively. Although SSR and ISSR markers led to dendrograms with different topologies, both separated the accessions into three main groups: I—Ubatuba-SP; II—Iguape-SP and Santa Catarina; and III—Mato Grosso. The accessions from Amazonas State were classified in group II with SSR and in a separate group with ISSR. Bayesian and principal coordinate analyzes conducted with both molecular markers corroborated the classification into three main groups. Higher variation was found within groups in the AMOVA analysis for both markers (66.5 and 60.6 % for ISSR and SSR, respectively), and higher Shannon diversity index was found for group II with SSR. Significant but low correlations were found between genetic and geographic distances (r = 0.08; p = 0.0007 for SSR and r = 0.16; p = 0.0002 for ISSR). Therefore, results from both markers showed a slight spatially structured genetic diversity in D. trifida accessions maintained by small traditional farmers in Brazil.     

Switchgrass (Panicum virgatum L.) from North Dakota—a New Bioenergy Crop for the Nemoral Zone of Europe

ABSTRACT

Parallel to the growing interest in switchgrass (Panicum virgatum L.) in southern countries of Europe, there is enhanced interest in knowing about its potential adaptability in the European regions with cool and moderate climates. The objective of this work was to characterize important agricultural parameters of switchgrass originated from North Dakota in order to identify the most valuable accessions for further research, propagation, and breeding in the Nemoral zone of Europe. The selection aimed at evaluating overwintering and productivity of switchgrass, with the ultimate objective of biomass quality improvement. Field trials were carried out in the central lowland of Lithuania during 2012–2014 on 33 germplasm accessions of switchgrass originating from North Dakota. Allthe tested accessions exhibited almost similar overwinter survival rate, i.e., 93.7–96.7%. Significant differences were observed in mean dry matter yields of all the tested accessions harvested once or twice per season (P < 0.05). The higher yielding accessions during both study years were differentiated. The yield potential of these accessions depended on a number of morphological traits, including internode thickness, plant height, panicle length, and leaf and stem weight per tiller (P < 0.05). Ash and mineral composition was associated with the genotype and the year of biomass harvest (P < 0.05). The switchgrass genotypes originating from North Dakota appeared to be adaptable to the European environment with cool and moderate climate and short growing season. The best-performing accessions can serve as a valuable genetic source for future breeding programmes.     

Evaluation of European emmer wheat germplasm for agro-morphological,grain quality traits and molecular traits

A total of 38 emmer wheat accessions, collected in several European countries, have been evaluated using agro-morphological traits, grain quality characteristics and molecular markers. The agronomic traits evaluated were: vernalisation response, winter hardiness, date of heading and flowering, lodging, plant height at harvest and resistances against powdery mildew (Erysiphe graminis), leaf rust (Puccinia recondita) and yellow rust (Puccinia striiformis). Evaluation of quality traits has been performed measuring the protein content, gluten quality and quantity. In addition, a baking test has been executed. The assessment of genetic variability has been carried out at the molecular level utilizing 6 SSR, 6 EST-SSR markers for genes with known function, and 6 ISSR primers for a total of 107 loci analyzed. Mean 1,000 kernel weight ranged from 31.6 to 39.0 g for winter emmer accessions and from 22.9 to 42.6 for spring emmer accessions. The protein content for both winter and spring emmer was considerably affected by environment and genotype. Nearly, all the spring emmer accessions showed resistance to powdery mildew. Measurement of wet gluten content revealed high values, ranging from 37.0 to 56.6 %. The molecular analysis showed a great value of genetic distance between accessions; the expected heterozygosity and the variance between accessions indicate an equal distribution of the alleles (i.e. alleles frequency almost equal) and the presence of great variability in the analyzed material. Finally, no defined clusters were obtained considering winter versus spring accessions as well as the molecular markers did not discriminate the accessions respect their origin.     

Analysis of genetic diversity and population structure of 135 dill (Anethum graveolens L.) accessions using RAPD markers

Dill (Anethum graveolens L.) leaf, seed and their essential oil are rich source of antioxidants. The plant is native in Southwest Asia and is cultivated in Europe, India and the United States. This study evaluated the genetic diversity structure of 135 accessions of A. graveolens from different continents, based on random amplified polymorphic DNA (RAPD) markers. The selected 10 RAPD primers generated a total of 142 highly reproducible bands, among which 89 were polymorphic. Percentage of polymorphism varied from 41.17 % (OPB20) to 92.85 % (OPB15) with an average of 77.74 %. A relatively high genetic diversity was detected among all the accessions with the Nei’s genetic diversity (H) values ranged from 0.346 (OPB07) to 0.444 (OPB18) with a mean of 0.401. When estimated for Shannon’s information index (I), it has ranged from 0.530 (OPB12) to 0.652 (OPB18), the mean was observed as 0.581. The respective values of H and I were found to be the highest value for primer OPB18. Cluster analysis of RAPD data using UPGMA algorithm based on Nei’s genetic similarity matrix placed the 135 accessions into two main clusters. Although a number of groups can be identified, the clusters show little to no association with the geographic origin of the material. The implication of the results of this study in developing a strategy for the conservation and breeding of dill germplasm are discussed.