Inter-retrotransposon Amplified Polymorphism Markers Research Articles

Phenotypic variability evaluation and genetic variation in F2 intraspecific hybrids of cucumber (Cucumis sativus L.) using retrotransposon-based markers

Abstract. Setiawan AB, Zahidah QA, Kaltsum DN, Purwantoro A. 2023. Phenotypic variability evaluation and genetic variation in F2 intraspecific hybrids of cucumber (Cucumis sativus L.) using retrotransposon-based markers. Biodiversitas 24: 2596-2604. Cucumber (Cucumis sativus L.) has a narrow genetic base compared to other Cucumis species. The genetic base of the cucumber can be improved by crossing two distantly related cultivars from different geographical locations. This study aimed to evaluate phenotypic variability and investigate genetic variation of F2 cucumber population using two retrotransposon-based markers, namely Inter Retrotransposon Amplified Polymorphism (IRAP)andInter-SINE Amplified Polymorphism(ISAP). Two parental lines and the selected 59 genotypes from F2 population were subjected to PCR analysis for DNA profiling. The phenotypic variation of F2 genotypes revealed significant diversity in fruit weight, fruit diameter, fruit radian, pedicel length, fruit length, and fruit ratio (length-diameter). The genetic variation of the F2 hybrids was successfully detected and discriminated by IRAP and ISAP markers. Both IRAP and ISAP markers showed high heterozygosity ranged from 0.4021 to 0.4997, with an average of 0.4649 and moderate polymorphic information content ranged from 0.3489 to 0.3929 with an average of 0.3648. Cluster analysis showed that the F2 population and parental lines were grouped into two major clusters with a similarity coefficient ranged from 0.67 to 0.96. These findings imply that the F2 population is highly segregated and can be utilized to create new cultivars of cucumber.

Assessment of genetic diversity of Prunus salicina 'Shazikongxinli' by morphological traits and molecular markers

Prunus salicina 'Shazikongxinli' is one of China’s most economically valuable and reputable Prunus salicina cultivars. Understanding the genetic diversity and population structure of 'Shazikongxinli' is imperative for excellent germplasm breeding and the preservation of genetic resources. This work used morphological markers, inter-retrotransposon amplified polymorphism (IRAP), and inter simple sequence repeat (ISSR) to assess the genetic variation status of 50 'Shazikongxinli', with 18 plum cultivars selected as the control outgroup. The results showed that the average Shannon–Weaver diversity index (H') of 32 qualitative traits in 50 tests 'Shazikongxinli' was 0.557, the average coefficient of variation of 11 quantitative traits was 15.57%, and a total of 232 and 105 polymorphic loci were obtained from 22 IRAP and 15 ISSR primers, respectively. All three marker systems showed relatively rich polymorphism, especially the IRAP markers. This might be related to the nature of the retrotransposons in the IRAP markers, which might be more suitable for intraspecific variability detection than ISSR. In addition, all three markers clustered the 68 tested germplasms into two groups. All of 'Shazikongxinli' clustered into one group, and most outgroup plum cultivars clustered into another group. This suggested a relatively narrow genetic base within the 'Shazikongxinli' population. These results would be useful in understanding the genetic diversity of the germplasm resources of 'Shazikongxinli' and provide a basic theoretical reference for breeding superior germplasm.

IRAPs in Combination with Highly Informative ISSRs Confer Effective Potentials for Genetic Diversity and Fidelity Assessment in Rhododendron.

The species belonging to the Rhododendron genus are well-known for their colorful corolla. Molecular marker systems have the potential to elucidate genetic diversity as well as to assess genetic fidelity in rhododendrons. In the present study, the reverse transcription domains of long terminal repeat retrotransposons were cloned from rhododendrons and used to develop an inter-retrotransposon amplified polymorphism (IRAP) marker system. Subsequently, 198 polymorphic loci were generated from the IRAP and inter-simple sequence repeat (ISSR) markers, of which 119 were derived from the IRAP markers. It was shown that in rhododendrons, IRAP markers were superior to the ISSRs in some polymorphic parameters, such as the average number of polymorphic loci (14.88 versus 13.17). The combination of the IRAP and ISSR systems was more discriminative for detecting 46 rhododendron accessions than each of the systems on their own. Furthermore, IRAP markers demonstrated more efficiency in genetic fidelity detection of in-vitro-grown R. bailiense Y.P.Ma, C.Q.Zhang and D.F.Chamb, an endangered species recently recorded in Guizhzhou Province, China. The available evidence revealed the distinct properties of IRAP and ISSR markers in the rhododendron-associated applications, and highlighted the availability of highly informative ISSR and IRAP markers in the evaluation of genetic diversity and genetic fidelity of rhododendrons, which may facilitate preservation and genetic breeding of rhododendron plants.

Identification of genetic regions associated with sex determination in date palm: A computational approach

Sex determination of date palm seedlings is the challengeable effort for breeders. Different studies based on molecular markers and genome sequencing have provided some insight in to the genetic regions related to sex determination in date palms in general. But due to differences in cultivar population structure and also cost of whole genome sequencing, we may need a more suitable approach in developing countries for this task. Therefore, we suggest using a combination of different available molecular markers and a computational approach to identify the genetic regions involved in sex differentiation in date palm cultivars. In this study we used twenty-three cultivars including 7 male and 16 female cultivars that were examined by 30 different dominant and co-dominant molecular markers which deal with different genomic regions. Grouping of the tree samples based on 178 loci resulted in genetic differentiation of the studied male and female palm trees. Multiple correspondence analysis (MCA) bi-plot also showed genetic difference within male and female trees. Heatmap plot specified those markers which differentiate date palm trees. SSR (simple sequence repeats) and IRAP (inter retrotransposon amplified polymorphism) markers provided sex linked markers for male cultivars. In present study, we introduced sex specific alleles for Iranian male date palm cultivars as a fast track in seedlings. Different association studies performed identified the candidate genetic regions which are significantly associated with sex differentiation in date palm cultivars.

Genetic diversity and gene-pool of Medicago polymorpha L. based on retrotransposon-based markers

The genus Medicago L. (Fabaceae) comprises approximately 87 different species of herbs and shrubs widespread from the Mediterranean to central Asia. Medicago polymorpha is a herbaceous legume that can be a useful pasture plant, in particular, in regions with a Mediterranean climate. It had aroused great interest due to high nutritious quality, highly palatability and N-fixing plan in neutral soil. There is no information on its population genetic structure, genetic diversity, and morphological variability in Iran. Due to the medicinal importance of this species, a genetic variability and populations’ structure study is performed studying 15 geographical populations of Medicago polymorpha. Therefore, we used six inter-retrotransposon amplified polymorphism (IRAP) markers and 15 combined IRAP markers to reveal within and among population genetic diversity in this plant. AMOVA test produced significant genetic difference (PhiPT = 0.46, P = 0.010) among the studied populations and also revealed that, 66% of total genetic variability was due to within population diversity while, 34% was due to among population genetic differentiation. Mantel test showed positive significant correlation between genetic distance and geographical distance of the studied populations. STRUCTURE analyses and population assignment test revealed some degree of gene flow among these populations. PCoA plot of populations was in agreement with UPGMA clustering of molecular data. These results indicated that geographical populations of Medicago polymorpha are well differentiated based on (IRAP) markers.

High genetic diversity in Aegilops tauschii Coss. accessions from North Iran as revealed by IRAP and REMAP markers

BackgroundAegilops tauschii Coss. as a donor of wheat D genome has an important role in wheat breeding programs. Genetic and phylogeographic diversity of 79 Ae. tauschii accessions collected from north and northwest of Iran were analyzed based on retroelement insertional polymorphisms using inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) markers. ResultsIn total, 306 and 151 polymorphic bands were amplified in IRAP and REMAP analyses, respectively. As a result, a high level of polymorphism was observed among the studied accessions as revealed by an average of 25.5 bands per primer/primer combination and mean PIC value of 0.47 in IRAP and an average of 25.16 bands per primer combination and mean PIC value of 0.47 in REMAP. Genetic relationships of the accessions were analyzed using distance- and model-based cluster analyses. ConclusionThe result showed that genetic distance did not seem to be related to geographic distribution, and the accessions could be divided into three groups, which was further supported by principal coordinate analysis. These results on genetic diversity and population structure of Ae. tauschii in Iran should provide important knowledge on genetic resources and their applications in wheat breeding programs.

Analysis of genetic variability in F2 interspecific hybrids of mung bean (Vigna radiata) using inter-retrotransposon amplified polymorphism marker system

Abstract. Fatmawati Y, Setiawan AB, Purwantoro A, Respatie DW, Teo CH. 2021. Analysis of genetic variability in F2 interspecific hybrids of mung bean (Vigna radiata) using inter-retrotransposon amplified polymorphism marker system. Biodiversitas 22: 4880-4889. Mung bean (Vigna radiata L. Wilczek) categorized as one of the pivotal annual crops of Vigna genera is commonly cultivated in rotation with the cereal crops during the drought season. Conversely, to ameliorate its stunted productivity, the interspecific hybridization technique has been introduced between the mung bean and the common bean to promote genetic improvement with the breeding projects in Indonesia. However, since mung bean is a self-pollinated crop and has a narrow genetic base, the selection and improvement of a specific trait using marker-assisted selection is more challenging. Hence, a precautionary investigation is imperative to evaluate the progenies resulting from interspecific hybridization using an ideal marker. This study aimed to investigate the genetic variability of the F2 population of the interspecific mung bean hybrids using retrotransposon-based markers, particularly Inter-Retrotransposon Amplified Polymorphism (IRAP) markers. In this study, we identified retrotransposon from the mung bean genome and determined the Long Terminal Repeat (LTR) sequence using the LTR Finder. The IRAP primers were designed from a conserved region of the LTR sequence. One hundred of the F2 interspecific hybrids generated from the crossing between mung bean and common bean were successfully discriminated by IRAP markers. The IRAP marker showed high heterozygosity and moderate Polymorphic Information Content (PIC) values. The IRAP markers were able to detect genetic variability in the F2 progenies resulting from the interspecific hybridization. Cluster analysis showed that 100 of the F2 progenies were grouped into three clusters. This study demonstrated that retrotransposon-based markers can offer an effective approach for evaluating the segregation in the F2 population of intercross hybrids in the mung bean.

Genetic diversity and gene-pool of Salicornia Sinus-Persica Akhani based on retrotransposon-based markers

Salicornia Sinus-Persica Akhani has been discovered in southern Iran, namely in Khuzestan, Bushehr, and Hormozgan, along salty and brackish rivers draining into the Persian Gulf well as estuaries and coastal habitats. Genetic diversity is an essential component of biological variability for conservation methods, particularly for rare and narrowly endemic species. Iran's folk's genetic structure, diversity, and morphological distinctions are unknown. Because of the plant's medicinal value, genetic diversity and folk structure were studied in six regional folks of Salicornia Sinus-Persica Akhani. To emphasize genetic variability within and across people in this plant, we employed six inter-retrotransposon amplified polymorphism (IRAP) markers and 15 combined IRAP markers. The AMOVA test indicated a substantial genetic difference across the folks investigated (PhiPT = 0.41, P = 0.010), as well as the fact that within-folk variation accounted for 80% of overall genetic diversity and genetic divergence between folks accounted for 20%. The Mantel test revealed a substantial positive connection between genetic distance and geographical distance across all groups investigated. According to STRUCTURE analysis and folk assignment tests, these folks exhibit some degree of gene flow-the UPGMA classification of molecular data matched with the PCoA plot of people. Based on (IRAP) markers, these findings revealed that the regional folks of Salicornia Sinus-Persica are incredibly distinct.

Genotypic variability and relationships of Sorghum bicolor accessions from Java Island, Indonesia based on IRAP markers

Abstract. Martiwi INA, Nugroho LH, Daryono BS, Susandarini R. 2020. Genotypic variability and relationships of Sorghum bicolor accessions from Java Island, Indonesia based on IRAP markers. Biodiversitas 21: 5637-5643. Sorghum (Sorghum bicolor (L.) Moench) is a multifunctional crop with high adaptability to various habitats and thus it is important to assess the genotypic variability of this crop species. This study aimed to reveal the genotypic variability and relationships of sorghum accessions using inter-retrotransposon amplified polymorphism (IRAP) molecular markers. Twenty-three sorghum accessions were collected from smallholder farmers in three provinces of Java Island during the 2019 planting season. The IRAP profiles generated using 10 primer combinations produced 233 scorable bands, with degree of polymorphism 75-96.9%. Cluster analysis using the neighbor-joining (NJ) method showed the formation of three groups corresponds to geographic origin of samples. The NJ dendrogram structure indicated high genotypic variability, and was supported by distribution pattern of accessions on the scatterplot constructed using principal coordinate analysis. The grouping of accessions did not correspond to classification of botanical races. Each group recognized from cluster analysis and principal coordinate analysis consisted of various races namely Bicolor, Guinea, Caudatum, and Kaffir. The fact that each group consisted of various botanical races indicated local adaptation and the maintenance of genotypic identity through farmers’ selection in traditional cultivation practices. It could be concluded, therefore, that geographical proximity and the practice of seed exchange between different regions showed considerable influence on the genotypic relationships of sorghum accessions.

Genetic diversity analysis of yardlong bean genotypes (Vigna unguiculata subsp. sesquipedalis) based on IRAP marker

Abstract. Widyawan MH, Wulandary S, Taryono. 2020. Genetic diversity analysis of yardlong bean genotypes (Vigna unguiculata subsp. sesquipedalis) based on IRAP marker. Biodiversitas 21: 1101-1107. Inter-Retrotransposon Amplified Polymorphism (IRAP) marker is a PCR-based molecular marker that detects polymorphism between retrotransposon sites. This marker has been utilized and successfully assessed genetic diversity in many crop species. Yardlong bean (Vigna unguiculata subsp. sesquipedalis) was an important vegetable legume crop that grown mainly for its fresh pod that rich in nutritional benefits for humans, ultimately dietary fiber and protein. Trends of people awareness to nutritional content of food are increasing, therefore breeding for quality traits is important. Genetic diversity analysis is an important and elementary step in breeding programs in order to determine the breeding strategy. The aims of this research are to perform an optimization of IRAP marker and applied it for genetic diversity analysis in 16 yardlong bean genotypes. Seven primers were used as marker in a pair or single combination and resulted in 11 optimized markers that able to be used for genetic diversity analysis. Sixteen yardlong bean genotypes consisting of commercial cultivars and local genotypes from Indonesia were genotyped using eleven IRAP markers. Marker polymorphism and diversity parameters from each marker i.e. Percentage of Polymorphic Loci (PPL), Expected Heterozygosity (He), Polymorphic Information Content (PIC), Effective Multiplex Ratio (EMR), Marker Index (MI), Discriminating Power (D), and Resolving Power (RP) were calculated. Based on those values, several markers used in this study were considered as informative and efficient in terms of analyzing genetic diversity in yardlong bean. Jaccard's method was used to measure genetic similarity and it is revealed that there is high level of similarity between yardlong bean genotypes used in this study. Thus, it is implied that there is a narrow genetic diversity of yardlong bean genotypes used in this study. Cluster analysis was performed to construct dendrogram based on genetic similarity and classified 16 yardlong genotypes into 4 clusters. Interestingly, majority of the clusters formed were not able to classified genotypes based on their origin. The result of cluster analysis then confirmed by Principal Coordinate Analysis (PCoA) that able to explain 47.76 % of total variation. The results of this study provide a foundation for the genetic diversity analysis based on IRAP marker and genetic improvement in yardlong bean.

Inter- and Intra-specific Genetic Diversity in Diospyros Using SCoT and IRAP Markers

The genus Diospyros contains more than 500 species, among them persimmon (Diospyros kaki Thunb.) is the most economically important species. However, the inter- and intra-specific genetic diversity remains unknown due to historic cultivation, domestication and introduction in different regions of China. In this study, we investigated the genetic diversity and relationship among 268 Diospyros accessions from different regions in China using start codon-targeted (SCoT) and inter-retrotransposon-amplified polymorphism (IRAP) markers. Among 268 samples, 232 accessions were D. kaki varieties and 36 were closely related species, that is, D. lotus (21), D. glaucifolia (1), D. virginiana (5), D. kaki Thunb. var. silvestris (3), D. oleifera (5) and D. deyangnsis (1). In our study, a total of 90 and 97 polymorphic alleles were obtained from nine SCoT and nine IRAP markers, respectively, and these markers displayed rich polymorphisms for evaluation of the genetic diversity among 268 samples. A study on the relationship, genetic structure and analysis of molecular variance (AMOVA) showed that inter- and intra-specific gene exchanges were frequent among/within the samples from five regions. Moreover, the genetic distance between the Southwest China (SWC) and the other regions was relatively far; the samples from North China (NC), East China (EC), South and Central China (SCC), Northwest China (NWC) regions had a relatively close relationship. The unweighted pair group method with arithmetic means (UPGMA) and population structure analysis indicated that persimmons within geographic regions were clustered together, which revealed that the samples from various regions exhibited gene exchange, and the geographical proximity of persimmons resulted in a more frequent exchange. In addition, the persimmon had a close relationship with D. kaki var. silvestris, D. deyangnsis and D. oleifera species, and exhibited a far distance with respect to D. virginiana. These SCoT and IRAP markers will be helpful for understanding of the inter- and intra-specific genetic diversity of Diospyros germplasms, which play an important role in the germplasm efficient conservation, identification and utilization for Diospyros resources.

Population differentiation and gene flow in Rrodium cicutarium: A potential medicinal plant

Erodium (Geranaiceae) species are distributed in different habitats of Iran. Some species are of medicinal importance while some are well known weeds. In arid and semi-arid regions, E. cicutarium has had some importance as a forage plant and is an important grazing plant and source of protein supplements to straw for ruminants in semi deserts and wastelands of the Middle East. There is no information on its population genetic structure, genetic diversity, and morphological variability in Iran. Due to the medicinal importance of this species, a genetic variability and populations? structure study is performed studying 15 geographical populations of E. cicutarium Therefore, we used six inter-retrotransposon amplified polymorphism (IRAP) markers and 15 combined IRAP markers to reveal within and among population genetic diversity in this plant. AMOVA test produced significant genetic difference (PhiPT = 0.39, P = 0.010) among the studied populations and also revealed that, 55% of total genetic variability was due to within population diversity while, 45% was due to among population genetic differentiation. Mantel test showed positive significant correlation between genetic distance and geographical distance of the studied populations. Networking, STRUCTURE analyses and population assignment test revealed some degree of gene flow among these populations. PCoA plot of populations based on morphological characters was in agreement with MDS plot of molecular data. These results indicated that geographical populations of E. cicutarium are well differentiated both in genetic content as well as morphological characteristics. Consensus tree based on morphological and genetic data separated some of these populations from the others suggesting the existence of ecotypes within this species.

Development and Deployment of High-Throughput Retrotransposon-Based Markers Reveal Genetic Diversity and Population Structure of Asian Bamboo

Bamboo, a non-timber grass species, known for exceptionally fast growth is a commercially viable crop. Long terminal repeat (LTR) retrotransposons, the main class I mobile genetic elements in plant genomes, are highly abundant (46%) in bamboo, contributing to genome diversity. They play significant roles in the regulation of gene expression, chromosome size and structure as well as in genome integrity. Due to their random insertion behavior, interspaces of retrotransposons can vary significantly among bamboo genotypes. Capitalizing this feature, inter-retrotransposon amplified polymorphism (IRAP) is a high-throughput marker system to study the genetic diversity of plant species. To date, there are no transposon based markers reported from the bamboo genome and particularly using IRAP markers on genetic diversity. Phyllostachys genus of Asian bamboo is the largest of the Bambusoideae subfamily, with great economic importance. We report structure-based analysis of bamboo genome for the LTR-retrotransposon superfamilies, Ty3-gypsy and Ty1-copia, which revealed a total of 98,850 retrotransposons with intact LTR sequences at both the ends. Grouped into 64,281 clusters/scaffold using CD-HIT-EST software, only 13 clusters of retroelements were found with more than 30 LTR sequences and with at least one copy having all intact protein domains such as gag and polyprotein. A total of 16 IRAP primers were synthesized, based on the high copy numbers of conserved LTR sequences. A study using these IRAP markers on genetic diversity and population structure of 58 Asian bamboo accessions belonging to the genus Phyllostachys revealed 3340 amplicons with an average of 98% polymorphism. The bamboo accessions were collected from nine different provinces of China, as well as from Italy and America. A three phased approach using hierarchical clustering, principal components and a model based population structure divided the bamboo accessions into four sub-populations, PhSP1, PhSP2, PhSP3 and PhSP4. All the three analyses produced significant sub-population wise consensus. Further, all the sub-populations revealed admixture of alleles. The analysis of molecular variance (AMOVA) among the sub-populations revealed high intra-population genetic variation (75%) than inter-population. The results suggest that Phyllostachys bamboos are not well evolutionarily diversified, although geographic speciation could have occurred at a limited level. This study highlights the usability of IRAP markers in determining the inter-species variability of Asian bamboos.

Development and use of retrotransposons-based markers (IRAP/REMAP) to assess genetic divergence among table grape cultivars

AbstractFor more than four decades after the introduction of cv. Italia (Vitis vinifera L.) in Brazil, several somatic mutations in the genome of cv. Italia and its somatic mutants gave rise to phenotypes which generated at least five new cultivars of fine table grapes. Since no molecular marker proved to be effective in discriminating cv. Italia (V. vinifera L.) and its coloured mutants (Rubi, Benitaka, Brasil, Black Star), primers for the long terminal repeat (LTR) sequences were developed to analyse Inter Retrotransposon Amplified Polymorphism (IRAP) and Retrotransposon-Microsatellite Amplified Polymorphism (REMAP), and investigate how the coloured cultivars derived from clonal propagations of somatic mutations are genetically structured. Primers for LTR sequences of IRAP and REMAP markers were edited from grape sequence databases available at a GenBank. Twenty-four primers, denominated DKS001–DKS024, were edited. Three hundred and forty-nine DNA segments were amplified by individual DKS primers and DKS/ISSR (Inter Simple Sequence Repeats) primer combinations, at an average of 13.96 amplicons per primer pair. High genetic divergence between the five cultivars was inferred from polymorphism in retrotransposons IRAP and REMAP. The analysis of polymorphism of IRAP and REMAP retrotransposons was crucial to show that clonal propagation of somatic mutations may lead towards the formation of genetically divergent cultivars by the formation of genetically structured vineyards and show the mixture of genomes within each cultivar.

LTR retrotransposons and highly informative ISSRs in combination are potential markers for genetic fidelity testing of tissue culture-raised plants in sugarcane

Testing the genetic fidelity of micropropagated clones with DNA markers could curtail the losses caused by somaclonal variation in sugarcane tissue culture industry. Evaluation of 32 inter-retrotransposon amplified polymorphism (IRAP) markers and 100 inter-simple sequence repeats (ISSRs) in 47 sugarcane accessions identified 20 (8 IRAPs and 12 ISSRs) polymorphic markers representing 98 loci. IRAP system was superior to ISSR in terms of marker index (2.68 as against 1.76), resolving power (2.85 as against 1.98), and polymorphic loci per assay (6 compared to 4.1), except mean polymorphic information content (0.31 and 0.34). Further evaluation of the 20 polymorphic markers in testing the genetic fidelity of micropropagated sugarcane clones identified a variant clone by three primers of ISSR and one IRAP marker (UBC810, UBC813, UBC840, and LTR6149 + 3′LTR). The unique amplicons from the somaclonal variant were validated by sequencing. Based on the number of bands amplified and proportion of polymorphic loci, a set of six ISSR and four IRAP markers has been recommended to test clonal fidelity for sugarcane tissue culture industry.

Activation of transposable elements and insertional polymorphism in Opuntia offspring as assessed by inter-retrotransposon amplified polymorphism markers

Activation of retrotransposon is a pivotal factor in the genesis of genetic polymorphism. Retrotransposon-based molecular markers are excellent tools for detecting genetic diversity and genomic changes associated with their activity. The objective of this study was to use IRAP markers to detect integration events of retrotransposon in Opuntia, and to compare IRAP and ISSR polymorphisms. To achieve these aims, five IRAP and five ISSR markers were analyzed on three varieties and their progenies. All IRAP primers showed an increase in the percentage of polymorphism, number of total bands, and polymorphic bands in the seedlings compared to their mother plants; that is, the offspring showed 13, 24 and 27 more bands than the mother plants from Tobarito, Montesa and Copena varieties, respectively. Conversely, sexual reproduction did not proportionally affect the variation in the number of ISSR bands, and neither did polymorphisms between mother plants and their offspring. Cluster and multivariate analyses based on IRAP and ISSR data revealed a clear separation between varieties, and there was no overlapping between seedlings of different varieties. The activation of retrotransposons in seedlings of opuntia with variable frequencies was evidenced. The presence of insertion and active retrotransposons may help to undertake studies on genetic diversity and evolution of Opuntia.

IRAP and REMAP based genetic diversity among varieties of Lallemantia iberica.

This study describes the genetic relationships among 34 varieties of Lallemantia iberica using inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP). Samples were collected from Agriculture Research Center of Urmia city (northwest Iran). Ten IRAP and REMAP primers generated 76 scorable electrophoretic bands with 78.94% polymorphism. The pair-wise Jacquard genetic similarity varied from 0.48 to 0.94 for IRAP and REMAP data combined. Average PIC values for IRAP and REMAP markers were 0.38. The retro-elements marker system produced 76 alleles in range of 100- 3000 bp. The cophenetic correlation coefficient between Jaccard's similarity matrix and the plotted dendrogram was 0.66. A dendrogram constructed based on COMPLETE LINKAGE. Cluster analysis of IRAP and REMAP data using the NTSYSpc 2.02 resulted in five clusters. The present study represents high genetic distance at genotype level suggesting that IRAP and REMAP markers are useful for Lallemantia iberica genetic diversity analysis.

Genetic fingerprinting of diploid and tetraploid cotton cultivars by retrotransposon-based markers

Cotton (Gossypium spp.) is the most important natural fiber and oil source worldwide. The genus Gossypium has 45 diploid and 5 allotetraploid species. Currently cotton has only 4 cultivated species, two tetraploid species [G. hirsutum L. and G. barbadense L., (2n = 4x = 52)] and two diploid species [G. arboreum L. and G. herbaceum L., (2n = 2x = 26]. Continuous artificial selection and cultivation of available cotton cultivars has led to genetic erosion and loss of useful genetic loci from the available cotton germplasm. Different molecular markers used in genetic fingerprinting of cottons, revealed narrow genetic variability. In order to provide data on genetic diversity present in our cotton germplasm collection, we carried out genetic fingerprinting study of 17 diploid and tetraploid cotton accessions by inter retrotransposon amplified polymorphism markers. The results showed low-moderate genetic variability (0.0–18%) among the studied cultivars. However, we obtained high genetic variability within each species (45–80%). Moreover, some specific bands (alleles) were identified in these species. Such moderate to high genetic variability in cotton germplasm is of high importance for choosing parental plants for hybridization. Inter retrotransposon amplified polymorphism markers could efficiently differentiate the cultivars and the studied diploid species from tetraploids. Therefore, these are suitable molecular markers for fast screening and genetic fingerprinting of large cotton germplasm.

Molecular insights into genetic diversity and population dynamics of five medicinal Eulophia species: a threatened orchid taxa of Africa.

Genetic diversity existing amongst five Eulophia orchid species were assessed using start codon targeted polymorphism (SCoT) and inter-retrotransposon amplified polymorphism (IRAP) markers. A total of 12 SCoT and 5 IRAP markers revealed an average of 63% genetic variability [SCoT = 63.87; IRAP = 64.95%] amongst the five Eulophia species investigated. The genetic similarities were assessed using both UPGMA and Bayesian approaches which indicated identical clustering patterns at a genetic similarity level of 50%. Analysis of molecular variance (AMOVA) revealed the presence of a significant degree of genetic variability, mostly compartmentalized within the species level. Amongst the five assessed Eulophia species, E. parviflora was the most genetically diverse representative whereas E. welwitschii was found to be least diverse based on a comparative assessment of various population genetic parameters like Nei's gene diversity (h) and Shannon's information index (I) with an overall gene flow value greater than 1. In order to evaluate the comparative marker efficiency, SCoT and IRAP marker data were subjected to various benchmark analyses like marker index, resolving power, polymorphic index content, multiplex ratio and effective multiplex ratio which revealed the robustness of both the marker techniques in assessment of genetic diversity. The present report provides the first molecular insights into the aspects of inter and intra specific genetic variability in medicinally as well as horticulturally important Eulophia species along with addressing their conservation concerns. In a nutshell, the present approach is simple, rapid and cost effective and can be extended for analysis of genetic diversity of other related plant species.

Assessment of genetic diversity and population structure of an endemic Moroccan tree (Argania spinosa L.) based in IRAP and ISSR markers and implications for conservation.

Argan Tree is well known for its precious oil extracted from its seeds particularly used for the nutritional and cosmetic benefits. Because of the high international demand, the argan tree suffers from overexploitation and its cultivation is rare. Thus, the assessment of the genetic variation of this endemic tree is critically important for designing conservation strategies. In the present study and for the first time, genetic diversity of the global natural distribution of argan tree (Argania spinosa L.) in Morocco was assessed. Four IRAP (inter-retrotransposon amplified polymorphism) primer combinations and seven ISSR (inter-simple sequence repeat) primers amplified 164 and 248 scorable polymorphic bands respectively. Polymorphic information content (PIC=0.27), resolving power (Rp=15) and marker index (MI=10.81) generated by IRAP primer combinations were almost identical to those generated by ISSR primers (PIC=0.27, Rp=9.16 and MI=12). AMOVA analysis showed that 49% of the genetic variation was partitioned within populations which is supported by Nei's genetic differentiation (Gst=0.5391) and the overall estimate of gene flow (Nm) being 0.4274. The STRUCTURE analysis, PCoA (principal coordinate analysis) and UPGMA (unweighted pair-group method with arithmetic mean) based on the combined data matrices of IRAP and ISSR divided the 240 argan genotypes into two groups. The strong differentiation observed might be due to the geographical distribution of argan tree. Our results provide crucial insight for genetic conservation programs of this genetic resource.