Investigating the genetic diversity of several varieties of Iranian tomato (Solanum lycopersicum) using RAPD and ISSR molecular markers

Background:Numerous studies have demonstrated the existence of approximately 7,500 genetic tomato varieties worldwide.Hence,it is crucial to assess the genetic diversity among tomato cultivars.This study aimed to investigate the genetic diversity of selected Iranian tomato cultivars(Solanum lycopersicum)using RAPD and ISSR molecular markers.Method:Ten RAPD primers and ten ISSR primers were employed to assess the genetic diversity among 10 tomato cultivars:Matin,RFT 112,Hirad,Golsar,Raha,Hengam,Hedah,Fasa,JS12,and Emerald.Data analysis involved the UPGMA algorithm and NTYSYSpc software.Results:RAPD analysis revealed close genetic proximity between Fasa and JS12,as well as between Raha and Hadieh.Conversely,the RFT 112,Hengam,Hirad,and Emerald cultivars exhibited significant genetic diversity within this group.ISSR primer analysis identified Hengam as the most diverse variety,while Matin,Emerald,and Vibrid,as well as Raha and JS12,displayed genetic similarities with minimal observed diversity.Furthermore,the overall analysis of the cultivars using RAPD and ISSR markers indicated that Hengam exhibited the highest diversity among all the varieties.Notably,Raha and JS12 demonstrated limited diversity in this analysis.Conclusion:This research demonstrates substantial genetic diversity among the investigated tomato varieties,with Hengam displaying the highest diversity within this group.Furthermore,ISSR markers proved more effective in determining genetic diversity in tomato plants.

Comparison of Genetic Diversity Between Local Cultivated Aromatic and Non-aromatic Rice in Yunnan Province

[ Objective] The genetic diversity of the local cultivated aromatic rice and non-aromatic rice in Yunnan Province were compared to provide further genetic resources for breeding practice. [Method] Genetic diversity of 10 aromatic rice and 45 non-aromatic rice were analyzed by 64 SSR primers covered on 12 rice chromosomes. [ Result] Per locus 5.44 and 7.98 alleles in average were detected, ranging from 2 to 12 and from 2 to 17 in aromatic and non-aromatic rice, respectively. Average genetic multiplicity index（Hs） was 0.46 and 0.67 respectively. The average polymorphism information content （PIC） was 0.43 and 0.58 in aromatic and non-aromatic rice respectively. [ Conclusion] The results indicated that genetic diversity was higher in non-aromatic rice than in aromatic rice.

Research Progress on Genetic Diversity and Its Ecological Conservation of Endangered Dongxiang Wild Rice (Oryza rufipogon Griff.)

It is of great importance for the analysis on genetic evolution mechanism, and rice breeding utilization by estimation and protection of genetic diversity of pre- sent DXWR （Oryza rufipogon Griff.）. This study has summarized genetic diversity and protection achievements of DXWR from many aspects like varied conservations, years, generations, other species of wild rice and cultivated rice. In this study, a u- nified and scientific evaluation system of genetic diversity is encouraged to be built and suggestions on research prospect and ecological conservation of DXWR genetic diversity have been proposed.

Comparative Analysis of Genetic Diversity and Structure in Rice Using ILP and SSR Markers

Genetic diversity of 36 rice entries from the United States Department of Agriculture （USDA） rice collection was assessed using 103 ILP （intron length polymorphism） and 54 SSR （simple sequence repeats） markers. A total of 236 and 332 alleles were detected by the ILP and SSR markers, respectively. On average, the SSR markers produced higher polymorphism information content value and number of alleles than the ILP markers. Whereas the Nei＇s genetic distance measured using the SSR markers was much higher than that measured using the ILP markers. Manters test indicated that there was a statistically significant correlation （r=0.827, P〈0.001 ） between the two marker systems. UPGMA clustering based on the ILP and SSR markers resulted in consensus dendrograms. The cophenetic correlation coefficient （r=0.918, 0.878 and 0.924, P〈0.001 for the ILP, SSR and combined markers, respectively） showed a highly accurate dendrogram represented the genetic distance among these entries. The 36 entries were divided into four groups. Four African Oryza glaberrima accessions were clustered within a distinct group （I）, and the remaining entries were separated into three groups （11, III and IV）. All the entries could be also clustered into two main groups： One was composed of III and IV, considered as indica group, and the other was composed of I （O. glaberrima） and II （japonica-like）. Model-based cluster analysis revealed that the japonica-like group maintained very pure ancestry while the indica group shared mixed ancestry, especially for group III, which had seven admixtures sharing from 19.5% to 30.0% of ancestry with group IV （based on SSR markers）. It is suggested that ILP and SSR markers could be very useful for the genetic study and breeding in rice.

The power of microsatellite markers and AFLPs in revealing the genetic diversity of Hashemi aromatic rice from Iran

Hashemi, a popular aromatic rice among Iranians, is famous for its fragrance and taste. Such features are major reasons for its higher price compared to non-aromatic varieties available in Iran. Therefore, the knowledge of genetic diversity of this profitable crop is a fundamental ineterst for plant breeders in future breeding programs. In the present research, genetic diversity among 35 genotypes of Hashemi aromatic rice （Oryza sativa L.） from Guilan and Mazandaran provinces of Iran was estimated using simple sequence repeat （SSR） and amplified fragment length polymorphism （AFLP） markers. Out of 21 SSR and 12 EcoRI-Msel AFLP marker combinations, only 16 SSRs and 10AFLPs exhibited polymorphic patterns while others were monomorphic. The 10 AFLP primer combinations produced a total of 142 of bands and 20 were polymorphic （14.08%）. Moreover, 40 out of 47 bands amplified with 16 SSR markers showed polymorphism （85.1%）. The average num- ber of alleles identified by SSR primers was 2.56 alleles per locus with a range of 2 to 4. The average value of polymorphic information content （PIC） was 0.393 and 0.468 for AFLP and SSR markers, respectively. However, the genetic similarity values ranged from 0.26 to 1 for SSRs and 0.21 to 1 forAFLPs. Later, a unweighted pair group method with arithmetic mean （UPGMA） dendrogram was generated and genotypes were clustered into four groups with SSRs at similarity coefficient of 0.55 while AFLPs clustered them into six groups at similarity coefficient of 0.41. Cluster analysis revealed a narrow genetic diversity and low correlation between geographical differentiation and genetic distance within cultivars.

Evaluation of Population Structure, Genetic Diversity and Origin of Northeast Asia Weedy Rice Based on Simple Sequence Repeat Markers

Weedy rice exerts a severe impact on rice production by competing for sunlight, water and nutrients. This study assayed the population structure, genetic diversity and origin of Northeast Asia weedy rice by using 48 simple sequence repeat markers. The results showed that weedy rice in Northeast Asia had a high genetic diversity, with Shannon＇s diversity index （I） of 0.748 and the heterozygosity （He） of 0.434. In each regional population, I value varied widely. The widest range of I （0.228-0.489） was observed in the weedy rice of Eastern China, which was larger than that of Northeast China and Korea （0.168-0.270）. The F-statistics of regional populations （Fis, Fit and Fst） also showed higher values in the weedy rice of Eastern China than those of Northeast China and Korea All weedy rice accessions were grouped into two clusters in the unweighted pair group method with arithmetic mean cluster analysis dendrogram, namely Eastern China branch and Northeastern China plus Korea branch. There was significant differentiation in genetic characteristics in weedy rice of northeastern and eastern Asia, especially in Eastern China.

Comparisons on Genetic Diversity among the Isonuclear-Alloplasmic Male Sterile Lines and Their Maintainer Lines in Rice

Four sets of rice isonuclear-alloplasmic lines including 16 male sterile lines and their maintainer lines were analyzed by using 91 pairs of SSR primers to study the genetic diversity of nuclear genome and their relative relationships. A total of 169 alleles were detected in the 16 lines, with a frequency of polymorphic loci of 53.85% and an average number of alleles per locus of 1.8, and the average gene diversity was 0.228. Four sets of the isonuclear-alloplasmic male sterile lines shared 146 identical alleles, corresponding to 86.39% of the total alleles; meanwhile, there are 23 different alleles among the tested materials, being 13.61% of the total alleles. On average, 78.70% identical alleles and 21.30% different alleles of the total alleles were detected between the isonuclear-alloplasmic male sterile lines and their maintainer lines. There were 53.85% identical alleles and 46.15% different alleles of the total alleles among the homozygous allonucleus male sterile lines. The fingerprints were established for some male sterile lines and maintainer lines. All the materials tested were divided into three groups at the 0.2 genetic distance based on the cluster analysis. Eight lines of Huanong A and Huayu A （including Huanong B and Huayu B） were in the first group, four lines of Kezhen A （including Kezhen B） in the second group, and four lines of Zhenshan 97A （including Zhenshan 97B） in the third group. For the isonuclear-alloplasmic male sterile lines, the similarity coefficient between Y （Yegong） type and WA （wild abortive） type or between CW （Raoping wild rice） and WA type reached 87-98%.

Genetic Diversity of Jute Mallow (Corchorus spp.) Accessions Based on ISSR Markers

Jute mallow is a nutritious leafy vegetable. The leaves are rich in proteins, vitamins and essential amino acids. Molecular characterization of Jute mallow with focus on improvement of leaf yield is scarcely reported. In the present study, inter sequence simple repeats (ISSR) molecular markers were employed to assess genetic diversity and relationships of 83 accessions of Jute mallow from different parts of Africa and Asia conserved at the World Vegetable Center East and Southern Africa. A total of 89 bands were amplified by 8 ISSR primers. Number of polymorphic bands per primer ranged from 2 to 6 with an average of 2.75 bands per primer. Polymorphic information content (PIC) values ranged from 0.390 to 0.760 with average of 0.53. Average Nei’s gene diversity (h) and Shannon’s information index (I) were 0.335 and 0.494 respectively. The highest pairwise genetic distance was 0.431 observed in a population from East Africa accessions. PC1 and PC2 axis explained 21.69% and 11.66% of the total variation respectively. UPGMA cluster analysis grouped the accessions into six main clusters at genetic similarity coefficient of 0.53 as standard value for classification. These results have important implications for jute mallow breeding and conservation.

Assessment of Genetic Diversity of Drought Tolerant and Susceptible Rice Genotypes Using Microsatellite Markers

The introgression of wild chromosomal segments into popular rice varieties is one of the potential approaches for developing varieties for drought stress condition. Sixteen genotypes, including nine indica, two tropical japonica and five chromosome segments substitution lines (CSSLs) with different levels of tolerance/susceptibility to drought stress, were selected for diversity study. Sixty-three microsatellite markers were utilized for assessing genetic diversity. A total of 95 alleles were amplified, and out of them, 60 were polymorphic. Six unique alleles, amplified by the microsatellite loci RM276, RM472, RM488, RM537, RM541 and RM28089, were identified in six genotypes, namely FR13A, Brahamanakhi, RUF44, Swarna-sub1, Brahamanakhi and Satyabhama. The highest genetic similarity was found among CSSLs. Polymorphism information content (PIC) value varied from 0 to 1.00 with an average of 0.66 per locus. Twenty-eight microsatellites were found to be polymorphic, which could be used in marker-assisted selection programme. All the sixteen genotypes were grouped into two major clusters at genetic similarity of 0.64. In the cluster I, five CSSLs identified as diverse genotypes had wild ancestor segments responsible for drought tolerance, and hence they could be utilized as potential donors. The popular Indian varieties, Swarna-sub1 and IR64-sub1, could be used as recurrent parents in the future breeding program for developing varieties for abiotic stresses such as submergence and drought.

Morphological and ISSR molecular markers reveal genetic diversity of wild hawthorns (Crataegus songorica K. Koch.) in Xinjiang, China

The wild hawthorn species, Crataegus songorica K. Koch., is an important wild germplasm resource in Xinjiang, China that has been endangered in recent years. The genetic diversity of C. songorica K. Koch. germplasm in five populations from Daxigou, Xinjiang, China were evaluated based on phenotypic traits and ISSR molecular markers to provide basic infor- mation on resource protection, rational utilization and genetic improvement. The F-value for the phenotypic differentiation coefficient of the 33 traits measured ranged from 0.266 to 15.128, and mean value was 13.85%. The variation among populations was found to be lower than that within population. A total of 303 loci were detected within the five populations by 12 primers. Within 298,polymorphic loci, the polymorphism was 98.35%, showing a high genetic diversity in C. songorica K. Koch. The gene diversity within population, total population genetic diversity, genetic differentiation coefficient and gene flow were 0.2779, 0.3235, 0.1408, and 3.0511, respectively. Our results showed that C. songorica K. Koch. from Xinjiang has a high level of genetic diversity at both the phenotypic and molecular levels. Significant genetic differentiation existed within population and the differentiation trend showed a regional association. And in this study, in situ and ex situ conser- vation approaches were raised for wild hawthorn protection utilization.

Relationship Between Hybrid Performance and Genetic Diversity Based on SSRs and ISSRs in Brassica napus L.

To investigate the relationship between genetic distance (GD) and hybrid performance, two types of molecular markers, microsatellites (simple sequence repeats, SSRs) and intro-simple sequence repeats (ISSRs), were employed to detect the genetic diversity of 3 double low self-incompatible lines and 22 male parental varieties of Brassica napus from different geographical origins. Hybrids were produced in a NCⅡ mating design by hand-pollination. The result indicated that 25 parental varieties (lines) could be divided into six groups by Un-weighted Pair Group Mathematics Average (UPGMA) clustering based on GDs. SI-1300 and SI-1320 could be singly clustered into one group, respectively. Varieties from China could be separated into another group, SI-1310 and varieties from foreign countries could be separated into other three groups. The grouping was generally consistent with parental pedigrees and geographical origins. Significant differences in yield, quality and phenological period traits were observed among these parent groups. Although hybrid yield/plant showed significantly positive correlation with genetic distance based on SSR and ISSR markers, but the determination coefficient was low. It appeared to be unsuitable for using the genetic distance based on SSR and ISSR markers to predict heterosis and hybrid performance in Brassica napus.

The loss of genetic diversity during captive breeding of the endangered sculpin, Trachidermus fasciatus, based on ISSR markers: implications for its conservation

Abstract Inter-simple sequence repeat （ISSR） markers were used to determine the genetic variation and genetic differentiation of cultured and wild populations of Trachidermus fasciatus, an endangered catadromous fish species in China. Six selected primers were used to amplify DNA samples from 85 individuals, and 353 loci were detected. Relatively low genetic diversity was detected in the cultured population （the percentage of polymorphic loci PPL=73.80%, Nei＇s gene diversity h--0.178 2, Shannon information index I=0.276 9）. However, the genetic diversity at the species level was relatively high （PPL-91.78%; h = 0.258 3, I= 0.398 6）. The UPGMA tree grouped together the genotypes almost according to their cultured and wild origin, showing distinct differences in genetic structure between wild and cultured populations. The pairwise F^t values confirmed significant genetic differentiation between wild and cultured samples. The cultivated population seems to be low in genetic diversity as a result of detrimental genetic effects in the captive population. The results suggest that ISSR markers are effective for rapid assessment of the degree of diversity of a population, thus giving important topical information relevant to preserving endangered species.

Analysis on Genetic Diversity of Radix Astragali by ISSR Markers

Radix Astragali has been an important traditional Chinese herbal medicine for over 2000 years. It is derived from two plant species, namely, Astragalus mongholicus [Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao] and Astragalus membranaceus [Astragalus membranaceus (Fisch.) Bge.] (Leguminosae ), according to the Pharmacopoeia of the People’s Republic of China. In this study, the genetic diversity and genetic relationships of Radix Astragali in China were analyzed by Inter-Simple Sequence Repeat (ISSR) markers. A total of 25 highly polymorphic ISSR primers were selected to amplify 95 Radix Astragali samples. Among 273 DNA bands amplified, 213 are polymorphic (percentage of polymorphic bands: 78%). The average value of the amplified bands was 10.9 for each primer, and the number varied from 4 to 20. The genetic diversity of the 95 Radix Astragali samples was analyzed by using POPGENE 1.32 software. The Nei’s genetic diversity index (h) and Shannon’s information index (I ) were 0.3590 and 0.5308, respectively, which indicated the abundant genetic diversity of Radix Astragali . The level of genetic diversity in A. membranaceus (h: 0.3109, I : 0.4657) was slightly lower than that in A. mongholicus (h: 0.3364, I : 0.4969). Considering the average genetic similarity coefficient by NTSYS analysis to cluster the A. membranaceus of nine habitats and A. mongholicus of five habitats, Radix Astragali samples were clustered into two groups according to place of origin. This clustering is different from traditional clustering, which divides groups according to species. Results obtained from this study will provide a theoretical basis for the molecular study on germplasm resources of Radix Astragali .

Study on Genetic Diversity of Turf Bamboo Based on ISSR Marker

[ Objective ] This study aimed to analyze the genetic diversity of turf bamboo species by using ISSR molecular marker technology. [ Method] Excellent turf bamboo species imported from France and domestic ornamental turf bamboo species were used as experimental materials for ISSR analysis, cluster analysis was conducted on 10 species of turf bamboo materials based on the obtained ISSR molectfiar ma^kers. [ Result] A total of 201 clear bands with good repeatability and high polymorphism were amplified with 21 ISSR primers, with a polymorphism rate of 93.1% ; similarity coefficients between different turf bamboo species ranged from 0.275 to 0.571, with an average similarity coefficient of 0. 357 ; according to the results of ISSR markers, 10 different ornamental turf bamboo species were di- vided into three categories by using UPGMA cluster analysis method. [Conclusion] Turf bamboo with different sources had relatively high genetic diversity, this study had provided theoretical and technical basis for the breeding, cultivation and vromotion of ornamental turf bamboo.

Genetic Diversity of Rice Landraces from Lowland and Upland Accessions of China

Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat （SSR） markers. The total number of alleles detected from all 324 tested accessions was 555 with an average allele number （Na） of 8.409 per locus, the average effective number of alleles （Ne） of 3.574 and the average Shannon＇s information index （I） of 1.378. The genetic diversity was higher for the indica landraces compared to the japonica landraces, and the upland landraces were more genetically diverse than the lowland landraces. The SSR markers, RM72, RM232, RM219, RM241, RM224 and RM3 showed the highest rates of polymorphism and these SSR markers were suitable to assess the genetic diversity of rice germplasm resources. A dendrogram of 324 accessions of lowland and upland landraces showed that all rice accessions were mainly subdivided into two groups, japonica and indica, with some being intermediate. The distribution of lowland and upland landraces among the japonica and indica rice groups was distinct, with obvious differentiation between the lowland and upland landraces in japonica rice, but no such clear distinction in indica rice.

Genetic Diversity Analysis of 44 Shares of Hibiscus cannabinus L. Germplasm Resources Using ISSR Molecular Marker

[Objective] This study was to reveal the genetic diversity and genetic relationship of the kenaf(Hibiscus cannabinus L.) resources from different origins, thus providing basis for genetic improvement and molecular marker-assisted breeding of kenaf. [Method] Ninety one ISSR molecular markers were used for amplification on 44 shares of kenaf germplasm resources, of which 21 showing good diversity and clear bands were chosen for PCR amplification. Based on amplification results, the genetic similarity coefficients among kenaf germplasm resources were calculated by using analytic software NTSYSpc-2.10e, and phylogenetic tree was then established via UPGMA. [Result] Totally 169 bands were amplified using the 21 screened primers, averagely 8.05 bands were amplified from each primer. Of them, 141 bands were polymorphic, accounting for 83.4%. When genetic similarity coefficient 0.887 was used as criterion L1, these 44 shares of kenaf germplasm could be classified to be 32 shares of cultivars and 12 shares of wild type or half-wild type varieties. When genetic similarity coefficient 0.897 was used as criterion L2, these 32 shares of cultivars could be further grouped into four sub-clusters. The genetic diversities between cultivars and wild type or half-wild type varieties were between 0.46-0.91, showing huge hereditary difference; while that among 32 cultivars were between 0.85-0.97, suggesting that genetic relationships among cultivars are relatively close and their genetic similarities are rather narrow. [Conclusion] ISSR could well determine the genetic similarities among kenaf germplasm resources and provide valuable molecular information for selecting parents of hybrid cross, which can lay a good foundation for DNA mapping of kenaf germplasm resources.

Genetic Diversity and Population Structure in Landraces and Improved Rice Varieties from India

A set of 50 rice genotypes comprising landraces, local selections, and improved varieties were characterized using simple sequence repeat（SSR） and inter simple sequence repeat（ISSR） markers to study genetic diversity and population structure. Following unweighted pair group method with arithmetic mean based clustering using binary data of polymorphic markers, the genotypes were grouped into 5 clusters and 11 sub-clusters, whereas population structure analysis separated 50 rice genotypes into 5 sub-populations. Grouping of rice genotypes showed better resemblance with the pedigree information of the genotypes. Both genetic diversity and population structure analysis separated majority of the improved varieties from landraces and local selections. Some of the SSR markers amplified unique alleles which were specific to a particular genotype and could distinguish them from the rest. The results indicate that these rice genotypes exhibit a higher genetic diversity and can be very useful in rice improvement program.

ISSR Analysis on Genetic Diversity of New Oil Palm Germplasm

[Objective]The aim of this study was to analyze the genetic diversity of new oil palm germplasm from DNA molecular level and provides a theoretical basis for the development and utilization of new oil palm germplasm. [Method]The genetic diversity of 22 new oil palm germplasm from Hainan and Yunnan were analyzed by ISSR technique. [Result]A total number of 201 bands were amplified with 23 ISSR primers,and polymorphic bands accounted for 41.8%. 22 oil palm varieties were divided into two groups by cluster analysis：Group I included new varieties of R1-R12 from Hainan and V20 from Yunnan,while group II included new varieties of V13-V22 from Yunnan,except V20. [Conclusion]New breeding oil palm germplasm from Hainan and Yunnan may come from different countries or regions.

Genetic Diversity and Relationship of Weedy Rice in Taizhou City, Jiangsu Province, China

Microsatellite markers and morphological characteristics were used to explore the genetic diversity and possible origin of weedy rice in Taizhou City, Jiangsu Province, China. Fifty-two weedy rice (Oryza sativa L.) accessions were compared with two wild rice, four hybrid rice and five cultivars using 22 simple sequence repeat (SSR) primer pairs. A total of 107 fragments were amplified, averaging 5.6 alleles per primer pair. The polymorphic index content (PIC) values ranged from 0.3077 to 0.7951, averaging at 0.5870. The average genetic distance of all samples ranged from 0.02 to 0.46 with an average of 0.262. The genetic distance among Taizhou weedy rice ranged from 0.03 to 0.44 with an average of 0.224. Cluster analysis showed that all the weedy rice accessions from Taizhou City were indica, and could be subdivided into different genotypes. The majority (86%) of weedy rice was most closely related to hybrid rice. The Taizhou weedy rice accessions were morphologically similar, but still could be delineated into indica or japonica group by some morphological traits. It is suggested that the levels of genetic and morphological diversities of weedy rice in Taizhou City are low and these weedy rice plants originated from the segregating progenies of hybrid rice that had naturally introgressed with cultivated rice.

Genetic Diversity of Tropical Hybrid Rice Germplasm Measured by Molecular Markers

Investigation of genetic diversity and relationships among breeding lines is of great importance to facilitate parent selection in hybrid rice breeding programs.In this study,we characterized 168 hybrid rice parents from International Rice Research Institute with 207 simple sequence repeat （SSR） and 353 single nucleotide polymorphism （SNP） markers.A total of 1 267 SSR and 706 SNP alleles were detected with the averages of 6.1 （SSR） and 2.0 （SNP） alleles per locus respectively across all lines.Based on the genetic distances estimated from the SSR and SNP markers separately and combined,the unrooted neighbor-joining cluster and STRUCTURE analyses consistently separated the 168 hybrid rice parents into two major groups：B-line and R-line,which is consistent with known parent pedigree information.The genetic distance matrices derived from the SSR and SNP genotyping were highly correlated （r=0.81,P 0.001）,indicating that both of the SSR and SNP markers have distinguishable power to detect polymorphism and are appropriate for genetic diversity analysis among tropical hybrid rice parents.A subset of 60 SSR markers were also chosen by the Core Hunter with 368 alleles,and the cluster analysis based on the total and subset of SSR markers highly corresponded at r=0.91 （P 0.001）,suggesting that fewer SSR markers can be used to classify and evaluate genetic diversity among parental lines.