Genetic Breeding Programs Research Articles

Flowering map of papaya germplasm: Support for genetic breeding and conservation programs

Brazil is the world's second leading producer of papaya. However, to sustain future production and growth particularly in the face of climate change, the development of new cultivars adapted to the country's various producing regions is a priority, mainly taking climate change into consideration. Research on the flowering phenology of papaya germplasm can facilitate choice of the most favorable moment to perform hybrid combinations for improvement. In this study, we analyzed the flowering phenology of 119 accessions of the Embrapa Papaya Active Germplasm Bank. The variables temperature, relative humidity and precipitation were collected from a nearby meteorological station and the data on average number of flowers produced per hermaphrodite plant were submitted to multivariate cluster analysis. The flowering of these accessions was influenced by environmental conditions, mainly rainfall patterns, characterizing seasonal behavior. The results showed two flowering peaks, the first coinciding with spring and the second with winter. In addition, we observed the formation of three different groups regarding flower production. The results obtained allow zoning of the flowering throughout the year for the 119 accessions, helping to improve the planning of hybridizations of interest. As far as we know, there are no reports in the literature of this type investigation with such a representative number of Carica papaya varieties.

Peroxidase and polyphenol oxidase activity in cassava genotypes infested with Phenacoccus manihoti

AbstractThe cassava mealybug, Phenacoccus manihoti (Matile‐Ferrero) (Hemiptera: Pseudococcidae), has become an important pest with major potential to damage cassava, Manihot esculenta Crantz (Euphorbiaceae), around the world. To find new sources of plant resistance, the development of P. manihoti on 18 cassava genotypes was evaluated (duration of embryonic, nymphal, egg–adult, pre‐oviposition, and oviposition periods, longevity, and fecundity), and the defense‐related peroxidase (POD) and polyphenol oxidase (PPO) activities in the leaves were measured. The fecundity of P. manihoti was the parameter most affected by the cassava genotype that the insect was fed. POD activity was negatively correlated with the intrinsic rate of increase (rm) of P. manihoti. PPO activity was negatively correlated with insect fecundity, net reproductive rate (R0), and rm and positively correlated with population doubling time. According to hierarchical groupings of the genotypes tested, three genotypes were resistant to P. manihoti, five were moderately resistant, nine were susceptible, and one was highly susceptible. This information could aid future genetic breeding programs, leading to development of more resistant commercial cassava varieties which could be used in integrated pest management systems.

The Transition Period Updated: A Review of the New Insights into the Adaptation of Dairy Cows to the New Lactation

Recent research on the transition period (TP) of dairy cows has highlighted the pivotal role of immune function in affecting the severity of metabolic challenges the animals face when approaching calving. This suggests that the immune system may play a role in the etiology of metabolic diseases occurring in early lactation. Several studies have indicated that the roots of immune dysfunctions could sink way before the “classical” TP (e.g., 3 weeks before and 3 weeks after calving), extending the time frame deemed as “risky” for the development of early lactation disorders at the period around the dry-off. Several distressing events occurring during the TP (i.e., dietary changes, heat stress) can boost the severity of pre-existing immune dysfunctions and metabolic changes that physiologically affect this phase of the lactation cycle, further increasing the likelihood of developing diseases. Based on this background, several operational and nutritional strategies could be adopted to minimize the detrimental effects of immune dysfunctions on the adaptation of dairy cows to the new lactation. A suitable environment (i.e., optimal welfare) and a balanced diet (which guarantees optimal nutrient partitioning to improve immune functions in cow and calf) are key aspects to consider when aiming to minimize TP challenges at the herd level. Furthermore, several prognostic behavioral and physiological indicators could help in identifying subjects that are more likely to undergo a “bad transition”, allowing prompt intervention through specific modulatory treatments. Recent genomic advances in understanding the linkage between metabolic disorders and the genotype of dairy cows suggest that genetic breeding programs aimed at improving dairy cows’ adaptation to the new lactation challenges (i.e., through increasing immune system efficiency or resilience against metabolic disorders) could be expected in the future. Despite these encouraging steps forward in understanding the physiological mechanisms driving metabolic responses of dairy cows during their transition to calving, it is evident that these processes still require further investigation, and that the TP—likely extended from dry-off—continues to be “the final frontier” for research in dairy sciences.

Automated Processing and Phenotype Extraction of Ovine Medical Images Using a Combined Generative Adversarial Network and Computer Vision Pipeline.

The speed and accuracy of phenotype detection from medical images are some of the most important qualities needed for any informed and timely response such as early detection of cancer or detection of desirable phenotypes for animal breeding. To improve both these qualities, the world is leveraging artificial intelligence and machine learning against this challenge. Most recently, deep learning has successfully been applied to the medical field to improve detection accuracies and speed for conditions including cancer and COVID-19. In this study, we applied deep neural networks, in the form of a generative adversarial network (GAN), to perform image-to-image processing steps needed for ovine phenotype analysis from CT scans of sheep. Key phenotypes such as gigot geometry and tissue distribution were determined using a computer vision (CV) pipeline. The results of the image processing using a trained GAN are strikingly similar (a similarity index of 98%) when used on unseen test images. The combined GAN-CV pipeline was able to process and determine the phenotypes at a speed of 0.11 s per medical image compared to approximately 30 min for manual processing. We hope this pipeline represents the first step towards automated phenotype extraction for ovine genetic breeding programmes.

Analysis of genetic diversity and structure across a wide range of germplasm reveals genetic relationships among seventeen species of Malus Mill. native to China

China is a center of diversity for Malus Mill. with 27 native species including 21 wild species and six domesticated species. We applied a set of 19 simple sequence repeat markers to genotype 798 accessions of 17 species (12 wild species and five cultivated species) of Malus originating from 14 provinces in China. A total of 500 alleles were detected. Diversity statistics indicated a high level of genetic variation as quantified by the average values of the effective allele number (Ne), expected heterozygosity (He), and Shannon’s Information Index (I) (10.309, 0.886, and 2.545, respectively). Malus sieversii (MSR; He=0.814, I=2.041, Ne=6.054), M. baccata (MBB; He=0.848, I=2.350, Ne=8.652), M. toringoides (MTH; He=0.663, I=1.355, Ne=3.332), and M. hupehensis (MHR; He=0.539, I=0.912, Ne=0.579) showed a higher level of genetic diversity in this study than the previous studies. MSR and MBB contributed to the origin and evolution of some accessions of M. domestica subsp. chinensis (MDC). However, other accessions of MDC showed a closer genetic distance with MBB and cultivated species, especially M. robusta (MRB), M. asiatica (MAN), and M. prunifolia (MPB). Not all accessions of MDC were descended from MSR in Xinjiang Uygur Autonomous Region of China. This research provides novel insights into the genetic relationships of Malus native to China, which will be useful for genetic association studies, germplasm conservation, and breeding programs.

Transcriptional responses to Fusarium oxysporum f. sp. lycopersici (Sacc.) Snyder & Hansen infection in three Colombian tomato cultivars

BackgroundFusarium oxysporum f. sp. lycopersici (Fol) is a compendium of pathogenic and non-pathogenic fungal strains. Pathogenic strains may cause vascular wilt disease and produce considerable losses in commercial tomato plots. To gain insight into the molecular mechanisms mediating resistance to Fol in tomato, the aim of our study was to characterize the transcriptional response of three cultivars (CT1, CT2 and IAC391) to a pathogenic (Fol-pt) and a non-pathogenic (Fo-npt) strain of Fo.ResultsAll cultivars exhibited differentially expressed genes in response to each strain of the fungus at 36 h post-inoculation. For the pathogenic strain, CT1 deployed an apparent active defense response that included upregulation of WRKY transcription factors, an extracellular chitinase, and terpenoid-related genes, among others. In IAC391, differentially expressed genes included upregulated but mostly downregulated genes. Upregulated genes mapped to ethylene regulation, pathogenesis regulation and transcription regulation, while downregulated genes potentially impacted defense responses, lipid transport and metal ion binding. Finally, CT2 exhibited mostly downregulated genes upon Fol-pt infection. This included genes involved in transcription regulation, defense responses, and metal ion binding.ConclusionsResults suggest that CT1 mounts a defense response against Fol-pt. IAC391 exhibits an intermediate phenotype whereby some defense response genes are activated, and others are suppressed. Finally, the transcriptional profile in the CT2 hints towards lower levels of resistance. Fo-npt also induced transcriptional changes in all cultivars, but to a lesser extent. Results of this study will support genetic breeding programs currently underway in the zone.

Genetic diversity evaluation in wild Muntingia calabura L. based on Random Amplified Polymorphic DNA (RAPD) markers

This present research was aimed to contribute fundamental knowledge about genetic diversity in wild Muntingia calabura. Random Amplified Polymorphic DNA (RAPD); a method that has been widely used to study genetic relationships in fruit crops. In this research investigation, eight accessions were collected, four accessions from Bangkok, Thailand and four accessions from Medan, North Sumatera, Indonesia. DNA fingerprinting of the eight accessions was performed using twelve RAPD markers (OPA-01, OPA-02, OPA-07, OPA-11, OPC-08, OPC-09, RAPD-01, RAPD-02, RAPD-03, RAPD-04, RAPD-05, RAPD-06). The obtained results revealed that all twelve primers produced polymorphic bands. UPGMA (unweighted pair-group method using arithmetic averages) method was used to determine the genetic distance. Based on dendrogram analysis, the eight accessions of M. calabura formed two main clusters. The range of genetic distance based on RAPD scores was 0.50–0.85. The RAPD technology is suitable for anonymous genomes due to its adaptability to situations with limited quantities of DNA and higher efficiency, and low cost. Researchers hope that present work is impactful and useful for genetic breeding programs in the future.

Characterization of whole mitogenome sequence of the Tongde yak (Bos grunniens)

Tongde County is located in the southeast of Qinghai Province, China, harboring rich yak genetic resources. In the present study, the complete mitochondrial genome (mitogenome) of the Tongde yak (Bos grunniens) was firstly sequenced using Illumina sequencing technique and the corresponding sequence characterization was identified. Our results showed that the mitogenome of Tongde yak is a circular molecule with 16,323 bp length consisting of 37 genes (13 protein-coding genes, 2 rRNA genes, 22 tRNA genes) and a non-coding control region (D-loop), which is consistent with most bovine species. The overall nucleotide composition was found as: A (33.72%), T (27.27%), C (25.80%), and G (13.21%), respectively, yielding a higher AT content (60.99%). The complete mitogenome sequence of Tongde yak would provide useful information for further studies on its genetic resource conservation and molecular breeding programmes in the future.

Genome-wide association and genomic prediction for scrotal circumference in Hereford and Braford bulls

Scrotal circumference (SC) is widely used as a selection criterion for bulls in breeding programs, since it is easily assessed and correlated with several desirable reproductive traits. The objectives of this study were: to perform a genome-wide association study (GWAS) to identify genomic regions associated with SC adjusted for age (SCa) and for both age and weight (SCaw); to select Tag SNPs from GWAS to construct low-density panel for genomic prediction; and to compare the prediction accuracy of the SC through different methods for Braford and Hereford bulls from the same genetic breeding program. Data of SC from 18,172 bulls (30.4 ± 3.7 cm) and of genotypes from 131 sires and 3,545 animals were used. From GWAS, the top 1% of 1-Mb windows were observed on chromosome (BTA) 2, 20, 7, 8, 15, 3, 16, 27, 6 and 8 for SCa and on BTA 8, 15, 16, 21, 19, 2, 6, 5 and 10 for SCaw, representing 17.4% and 18.8% of the additive genetic variance of SCa and SCaw, respectively. The MeSH analysis was able to translate genomic information providing biological meanings of more specific gene functions related to the SCa and SCaw. The genomic enhancement methods, especially single step GBLUP, that combined phenotype and pedigree data with direct genomic values generated gains in accuracy in relation to pedigree BLUP, suggesting that genomic predictions should be applied to improve genetic gain and to narrow the generation interval compared to traditional methods. The proposed Tag-SNP panels may be useful for lower-cost commercial genomic prediction applications in the future, when the number of bulls in the reference population increases for SC in Hereford and Braford breeds.

Simple Sequence Repeats Marker based Detection of Genetic Diversity of Indian Bean Dolichos lablab (L.) of Family Fabaceae

Background: Assessment and molecular characterization of genetic diversity among the Dolichos lablab (L.) have huge implication in scheming strategies for breeding. In India, there is less comprehensive information on the potential genetic diversity of lablab bean and this is a major challenge for systematic use of lablab bean in genetic breeding programs. To exploit the available trait of interest, the genetic diversity of the locally available genotypes must be known. The PCR-based SSR approach requires just nanogram amounts of template DNA, subjected to quick detection and less influenced by environment. In this manner SSR have been utilizing broadly to study hereditary assorted qualities of yields.Methods: In this study, genetic diversity on ten Indian Dolichos lablab (L.) genotypes were surveyed utilizing SSR markers at Department of Botany, Bundelkhand University, Jhansi during 2019-20 got from Indian gene bank. For SSR analysis, 5 primers were used for checking the diversity in Dolichos lablab (L.) and the performance of markers were measured by using 4 parameters (1) PIC, (2) Mean resolving Power, (3) Resolving Power and (4) MI. Result: SSR (05) markers produced a total of 51 bands, out of which 45 bands (88.23%) were polymorphic which varies from 6 (Primer-111) to 15 (Primer-AGB-9) with mean of 10.5 bands per primer. The polymorphic information content value ranges from 0.265 to 0.488 with a mean value of 0.390. The value of Matrix index is 3.2. The value of resolving power ranges from 2.2 to 12.60 with a mean value of 7.40. In the UPGMA dendogram, the 10 genotypes were separated into two main clusters with all the primers used. Our present examination uncovered that genetic markers might be effectively used for deciding hereditary variety and connections in Dolichos lablab (L.) genotypes and could be utilized as a part of breeding programs.

Progress on inheritance and gene cloning for rice grain quality in Jiangsu province.

In China, rice (Oryza sativa L.) is a major cereal crop of great importance maintaining the food security and sustainable agricultural development. Jiangsu is one of the main provinces for rice production. After more than 40 years of development, the yield and quality of rice grain have made great progress. Rice grain quality is a complex trait involving production, processing, marketing and consumption of the grain. In this review, we summarize the progress on the genetic basis of main grain quality traits in the rice variety breeding in Jiangsu province and point out the achievement of each milestone. With a focus on the genetic regulation of grain appearance, eating and cooking quality and nutritional quality, we describe the classic genetic rules and molecular basis of rice grain quality traits and review the function of major genes that regulate corresponding traits. The genetics and improvement of grain quality achieved in Jiangsu province was highlighted on the domestic and international rice breeding programs. In particular, with the advance of breeding conception in terms of functional genomics and genetic regulatory networks, the specific molecular design for grain quality improvement will be the future direction of rice genetic breeding program of Jiangsu Province.

Genetic diversity of Algerian sorghum (Sorghum bicolor (L.) Moench) landraces by using agro-morphological markers

The present study was performed to assess the native Algerian sorghum germplasm,20 accessions originating from the South of Algeria and one introduced commercial hybrid were evaluated for 12quantitative agro-morphological markers. Analysis of variance revealed significant differences (p ˂ 0.05) between accessions for all characters. Comparison of means by Duncan’s least significant test separate accessions into several homogeneous groups. It was found that sorghum landrace Ai19 showed the highest scores of final height (317 cm) and biomass dry yield (38 tons), Ai13 showed shortest vegetative cycles by 75 days to 50% flowering and the highest exploration of water to accumulate dry matter. The first two-principle component showed together more than 76% of the total variation. Clustering analysis showed that the 20 accessions were divided into four groups, mainly differentiated by forage production, days to 50% of flowering, final height, tillering capacity and leaf characteristics. The current study demonstrates that the characterization of the entire collection revealed a great phenotypic variability within the accessions and showed those that have markers of agronomic interest. Agro-morphological traits were very practical in detecting variation between local and commercial hybrid sorghum. Landraces Ai19, Ai13 and Fr1, through their valuable agro-morphological markers, could be used in sorghum genetic breeding programs.

Genetic diversity of Algerian sorghum (Sorghum bicolor (L.) Moench) landraces by using agro-morphological markers

The present study was performed to assess the native Algerian sorghum germplasm,20 accessions originating from the South of Algeria and one introduced commercial hybrid were evaluated for 12quantitative agro-morphological markers. Analysis of variance revealed significant differences (p ˂ 0.05) between accessions for all characters. Comparison of means by Duncan’s least significant test separate accessions into several homogeneous groups. It was found that sorghum landrace Ai19 showed the highest scores of final height (317 cm) and biomass dry yield (38 tons), Ai13 showed shortest vegetative cycles by 75 days to 50% flowering and the highest exploration of water to accumulate dry matter. The first two-principle component showed together more than 76% of the total variation. Clustering analysis showed that the 20 accessions were divided into four groups, mainly differentiated by forage production, days to 50% of flowering, final height, tillering capacity and leaf characteristics. The current study demonstrates that the characterization of the entire collection revealed a great phenotypic variability within the accessions and showed those that have markers of agronomic interest. Agro-morphological traits were very practical in detecting variation between local and commercial hybrid sorghum. Landraces Ai19, Ai13 and Fr1, through their valuable agro-morphological markers, could be used in sorghum genetic breeding programs.

Multidimensional scaling for divergence analysis in pepper

Pepper plants of the genus Capsicum present wide genetic variability for phenotypical characters. The joint analysis of quantitative and qualitative characters is a more complete indicator to identify the existing variability in populations of plants. This work aimed to evaluate the genetic divergence within F3 populations of Capsicum annuum L. through the multidimensional scaling based on the joint analysis of quantitative and qualitative data. The work was developed in at the Center of Agrarian Sciences of the Federal University of Paraíba, state of Paraíba, Brazil. Eight populations of an F3 generation were employed, performing the characterization of 36 qualitative and quantitative characteristics. The experimental design was in randomized blocks, with eight treatments and 50 replications. The non-metric multidimensional scaling (nMDS) was performed based on Gower’s dissimilarity matrixes. Dispersion diagrams were built to present the nMDS solutions in the bidimensional space. The nMDS mapping was efficient on estimating divergence within populations with Kruskal’s Stress below 20%. The internal uniformity presented by populations P-4, P-5, P-6, P-7, and P-8 is an indicator that the genotypes of these populations are suitable to be used in future genetic breeding programs of ornamental peppers. Conversely, populations P-1, P-2, and P-3 presented the greatest dispersion, characterizing phenotypical variability. The multidimensional scaling was efficient to estimate the genetic divergence among and within F3 populations of ornamental pepper

Effects of pyruvate decarboxylase (pdc1, pdc5) gene knockout on the production of metabolites in two haploid Saccharomyces cerevisiae strains

Saccharomyces cerevisiae has good reproductive ability in both haploid and diploid forms, a pyruvate decarboxylase plays an important role in S. cerevisiae cell metabolism. In this study, pdc1 and pdc5 double knockout strains of S. cerevisiae H14-02 (MATa type) and S. cerevisiae H5-02 (MATα type) were obtained by the Cre/loxP technique. The effects of the deletion of pdc1 and pdc5 on the metabolites of the two haploid S. cerevisiae strains were consistent. In S. cerevisiae H14-02, the ethanol conversion decreased by 30.19%, the conversion of glycerol increased by 40.005%, the concentration of acetic acid decreased by 43.54%, the concentration of acetoin increased by 12.79 times, and the activity of pyruvate decarboxylase decreased by 40.91% compared to those in the original H14 strain. The original S. cerevisiae haploid strain H14 produced a small amount of acetoin but produced very little 2,3-butanediol. However, S. cerevisiae H14-02 produced 1.420 ± 0.063 g/L 2,3-BD. This study not only provides strain selection for obtaining haploid strains with a high yield of 2,3-BD but also lays a foundation for haploid S. cerevisiae to be used as a new tool for genetic research and breeding programs.

Screening of African Yam Bean Accessions for Imbibition and Seed Physiological Quality

African yam bean is a nutritionally-important but neglected food crop with several health benefits. But its large scale cultivation and consumption are still limited by lack of systematic genetic improvement and breeding programme for the crop. Preliminary studies have established that the inherent field establishment potential of African yam bean is low. Hence the need to screen available accessions to identify those with outstanding seed physiological qualities for selection as parental materials for further improvement. Thirty-four African yam bean accessions were collected from different farmers in five states of Southeastern Nigeria. Seed physiological quality (viability and vigour) was assessed using hundred seed weight, water imbibition, standard germination, accelerated ageing and conductivity tests. The mean squares due to varietal effect were significant (p < 0.05) for germination index and highly significant (p < 0.01) for all other traits. Accessions ENAGag, ENAGmg 1 and, ENAGmg 2 had high standard (> 80%) and accelerated ageing (> 70%) germination percentages. Only 11 of the accessions had an accelerated ageing germination percentage of above 50%. All but one of the 34 accessions had conductivity values less than 5.00 µScm-1 g-1. On the average, African yam bean seeds require up to 76.9% moisture of their initial weight over a period of approximately 53 hours prior for the commencement of germination process. Accessions ENAGag, ENAGmg 1, ENAGmg 2, ENNKob, ENNSog, IMISis, IMOKeo 1 and IMOKeo 3 were outstanding and are therefore potential candidates for genetic improvement of seed quality in African yam bean.

Association of spectroscopically determined leaf nutrition related traits and breeding selection in Sassafras tzumu

BackgroundPlant traits related to nutrition have an influential role in tree growth, tree production and nutrient cycling. Therefore, the breeding program should consider the genetics of the traits. However, the measurement methods could seriously affect the progress of breeding selection program. In this study, we tested the ability of spectroscopy to quantify the specific leaf nutrition traits including anthocyanins (ANTH), flavonoids (FLAV) and nitrogen balance index (NBI), and estimated the genetic variation of these leaf traits based on the spectroscopic predicted data. Fresh leaves of Sassafras tzumu were selected for spectral collection and ANTH, FLAV and NBI concentrations measurement by standard analytical methods. Partial least squares regression (PLSR), five spectra pre-processing methods, and four variable selection algorisms were conducted for the optimal model selection. Each trait model was simulated 200 times for error estimation.ResultsThe standard normal variate (SNV) to the ANTH model and 1st derivatives to the FLAV and NBI models, combined with significant Multivariate Correlation (sMC) algorithm variable selection are finally regarded as the best performance models. The ANTH model produced the highest accuracy of prediction with a mean R2 of 0.72 and mean RMSE of 0.10%, followed by FLAV and NBI model (mean R2 of 0.58, mean RMSE of 0.11% and mean R2 of 0.44, mean RMSE of 0.04%). High heritability was found for ANTH, FLAV and NBI with h2 of 0.78, 0.58 and 0.61 respectively. It shows that it is beneficial and possible for breeding selection to the improvement of leaf nutrition traits.ConclusionsSpectroscopy can successfully characterize the leaf nutrition traits in living tree leaves and the ability to simultaneous multiple plant traits provides a promising and high-throughput tool for the quick analysis of large size samples and serves for genetic breeding program.

Genetic parameter estimates and identification of SNPs associated with growth traits in Senegalese sole

Breeding programs are essential for aquaculture. The present study was conducted to investigate the genetic parameters of four growth traits in Senegalese sole. Families were produced by mass spawning (n = 2171 offspring) from an industrial broodstock. Weight, total area, standard length and width (the two latter measured directly on the fish and by image analysis) were determined before the on-growing stage (age ~ 400 d) and at harvest (~800 d) in RAS. Phenotypic data are presented and discussed. Females grew faster than males and a high variation of sex ratios by family was observed. Heritabilities were high for all traits ranging from 0.568 to 0.609 at 400 d and from 0.424 to 0.500 at 800d. The genetic correlations between traits were very high (>0.94) at both ages. Genetic estimates for traits measured in vivo and by digital image analysis were similar. To investigate genomic regions associated with these growth traits, a low-density array using a set of 60 single nucleotide polymorphisms (SNPs) distributed in 17 linkage groups was designed. Using samples from wild fish, a total of 49 assays for SNP analysis were validated. The association analysis was carried out using two fast-growth families and two slow-growth families (n = 279). Two significantly-associated SNPs with most of the traits at both ages were detected. They were located in the general transcription factor 3C polypeptide 4 (gtf3c4) and the mitochondrial fission process protein 1 (mtfp1). Results are of high relevance for genetic breeding programs in this species.

Genomic SSR and EST‐SSR markers for phylogenetic and pedigree reconstructions—A comparison in sea buckthorn

AbstractSimple sequence repeat (SSR) markers play an important role in genetic and molecular breeding programs, especially for non‐model species. We identified SSRs from expressed sequence tags (EST‐SSRs) and whole genome sequences (gSSRs), by analysing the transcriptome and genome of the Mongolian sea buckthorn (Hippophae rhamnoides subsp. mongolica) cultivar ‘Sunny’. Using the same number of loci, EST‐SSRs showed higher transferability to Hippophae than gSSRs, and phylogenetic trees based on EST‐SSRs demonstrated higher resolution for classifying Hippophae species and subspecies into clades, possibly due to high conservatism and/or existence of adaptive divergence between species/subspecies in coding sequence regions. In contrast, parentage analyses showed that gSSRs were more effective at resolving parentage than EST‐SSRs due to higher level of polymorphism in gSSRs. The markers developed in this study can be used in the identification and pedigree reconstruction of species/subspecies of sea buckthorn, while their usage in clarifying phylogenetic relationship among species remains to be discussed. The comparison between EST‐SSRs and gSSRs would provide insight into the trade‐off between differentiation and polymorphism in marker selection for breeding programs.

Genetic Structure of Some Iranian, New and Old Worlds Linum Usitatissimum L. Populations

In current evaluation, the genetic structure and diversity were investigated in ten linseed populations collected from five countries belong to two continents (America and Eurasia) to find different genotypes for introducing them for genetic breeding programs. We selected these populations, because they belong to different regions of Holarctic and Paleotropical phytogeographic kingdoms. For this purpose, the nuclear DNA was extracted using the CTAB-modified method and amplified using 32 ISSR primers. Genetic diversity parameters and polymorphism indexes widely varied among the evaluated populations. Moreover, the results of the analysis of variance test proved the significant genetic differences, which its great part belonged to inter-population rather than intra-population. These findings were consistent with the high GST and HT levels and small amounts of HS and populations grouping in MDS plot, which revealed low amount of within population’s diversity, except those for Arak and Masal populations. In addition, low amount of Nm, indicating a flat rate of gene flow and strong population differentiation. According to the STRUCTURE analysis and UPGMA tree of Nei’s genetic distance, six genotypes were recognized among the studied populations. In the detected genotypes, populations with long geographical distances have the same genetic structure. It seems that the populations with the similar genetic structures have been originated from the same genetic diversity center. Hence, we assume that there are at least six centers of genetic diversity for flax in the world; however, evidences of ancestral gene flow were detected in genetic structure. These findings are consistent with the theory that there are several centers for flax genetic diversity around the world. Due to the high intraspecific diversity in Masal and Arak populations, individuals of these populations have great importance for genetic breeding programs of this species.