Polymorphism Information Content Research Articles

Decoding genetic diversity and population structure of Brassica species by inter primer binding site (iPBS) retrotransposon markers

AbstractMarker-assisted breeding serves as a potent tool for screening target germplasm, assessing genetic diversity, and determining breeding potential of a crop. Therefore, inter primer binding site (iPBS)-retrotransposons marker system was employed to evaluate a collection of 33 Brassica genotypes, including 10 Brassica juncea, 5 B. oleracea, 7 Sinapis alba, 5 B. nigra, and 6 B. rapa, were utilized to evaluate their genetic diversity and variations 10 polymorphic primers that generated a total of 144 bands. Various diversity indices were calculated in the studied germplasm, including polymorphism information content (0.13–0.30), effective number of alleles (1.217–1.689), Shannon’s information index (0.244–0.531), and gene diversity (0.148–0.370). These indices collectively affirmed substantial genetic variations within the germplasm. Molecular variance analysis revealed that the majority (62%) of genetic variations were present within populations. The Brassica accessions were categorized into three populations utilizing a model-based structure algorithm. Evaluation of diversity indices based on the structure indicated that populations III and II exhibited higher diversity. Principal coordinate analysis and neighbor-joining analysis further corroborated the three distinct populations, confirming the reliability of the STRUCTURE analysis. Notably, the genetic distance assessment identified BN1 and BN3 from B. nigra species and the genotypes BO1 and BO3 from B. oleracea as genetically diverse mustard accessions. The extensive genetic diversity observed within the Brassica germplasm underscores its significance as a valuable genetic resource for comprehensive Brassica breeding programs. Moreover, these accessions hold promise as suitable candidates for heterosis breeding initiatives aimed at improving mustard production.

Identification and characterization of functionally relevant SSR markers in natural Dalbergia odorifera populations

BackgroundDalbergia odorifera is a rare and precious rosewood specie, which is valued for its amber tones, abstract figural patterns, and impermeability to water and insects. However, the information on genetic diversity and marker-assisted selection breeding of D. odorifera is still limited. Simple sequence repeat (SSR) markers are an ideal tool for genetic diversity analysis and marker-assisted molecular breeding for complex traits.ResultsHere, we have developed SSR markers within candidate genes and used them to explore the genetic diversity among D. odorifera germplasm resources. A total of 635 SSR loci were identified. The proportions of mono-, di- and tri-nucleotide repeat motifs were 52.28%, 22.99% and 21.42%, respectively. From these, a total of 114 SSR primers were synthesized, of which 24 SSR markers displayed polymorphism (polymorphic information content (PIC) > 0.25). Subsequently, these polymorphic markers were used for the genetic diversity analysis of 106 D. odorifera individuals from 11 natural populations. According to the genetic diversity analysis of D. odorifera natural populations, the average observed heterozygosity (Ho) was 0.500, the average expected heterozygosity (He) was 0.524, and the average Shannon’s information index (I) was 0.946. These indicated that the natural populations had moderate genetic diversity. AMOVA analysis showed that 5% of the total variation was within the individuals of a population, whereas 95% of the variation was among the individuals of the populations, indicating a high degree of genetic variation between populations. On the basis of their genetic structures, these populations could be divided into four groups.ConclusionsOur study provides important experimental resources for genetic studies and assists in the program of molecular breeding of D. odorifera wood formation.

Genetic structure and molecular analysis of the species of the genus Artemisia L. (Asteraceae) distributed in Azerbaijan

In this study, the phylogenetic relationships and genetic structure of 10 collected genotypes of Artemisia szowitziana (Besser) Grossh and Artemisia fragrans Willd. species from different regions of Azerbaijan were investigated using RAPD primers. A total of 94 amplicons were amplified using selected RAPD primers. Among them 3 band with OPA-02 primers and 12 band with OPW-17 primers were amplified. The highest polymorphism among the investigated RAPD markers was 100, 90.91 and 90%, which has been obtained by OPW-17, OPT-19, and OPT-20 primers, respectively. However, the calculated average value of polymorphism was as high as 72.79% based on 10 different RAPD markers. The average PIC (Polymorphism Information Content) value (0.864) has indicated the rich genetic diversity among the studied samples. The cluster analyses by using Jaccard similarity index and UPGMA method classified all Artemisia L. samples into 6 major groups. Principal Component Analysis (PCA) justified 74.22% of the total variance. Based on the results obtained, it has been observed that there is a wide range of diversity in the molecular level between the population of Artemisia szowitziana (1-2 and 4-6 samples) and Artemisia fragrans (3, 5, 7 and 8, 9, 10 samples) and between population of the Artemisia species in Azerbaijan.

Analysis of Elimination Effects of Inbreeding on Genotype Frequency in Larval Stages of Chinese Shrimp.

Marine animals possess genomes of considerable complexity and heterozygosity. Their unique reproductive system, characterized by high fecundity and substantial early mortality rates, increases the risk of inbreeding, potentially leading to severe inbreeding depression during various larval developmental stages. In this study, we established a set of inbred families of Fenneropenaeus chinensis, with an inbreeding coefficient of 0.25, and investigated elimination patterns and the manifestations of inbreeding depression during major larval developmental stages. Reduced-representation genome sequencing was utilized to explore the genotype frequency characteristics across two typical elimination stages. The results revealed notable mortality in hatching and metamorphosis into mysis and post-larvae stages. Inbreeding depression was also evident during these developmental stages, with depression rates of 24.36%, 29.23%, and 45.28%. Segregation analysis of SNPs indicated an important role of gametic selection before hatching, accounting for 45.95% of deviation in the zoea stage. During the zygotic selection phase of larval development, homozygote deficiency and heterozygote excess were the main selection types. Summation of the two types explained 82.31% and 89.91% of zygotic selection in the mysis and post-larvae stage, respectively. The overall distortion ratio decreased from 22.37% to 12.86% in the late developmental stage. A total of 783 loci were identified through selective sweep analysis. We also found the types of distortion at the same locus could change after the post-larvae stage. The predominant shifts included a transition of gametic selection toward normal segregation and other forms of distortion to heterozygous excess. This may be attributed to high-intensity selection on deleterious alleles and genetic hitchhiking effects. Following larval elimination, a greater proportion of heterozygous individuals were preserved. We detected an increase in genetic diversity parameters such as expected heterozygosity, observed heterozygosity, and polymorphic information content in the post-larvae stage. These findings suggest the presence of numerous recessive deleterious alleles and their linkage and suggest a major role of the partial dominance hypothesis. The results provide valuable insights into the mechanisms of inbreeding depression in marine animals and offer guidance for formulating breeding strategies in shrimp populations.

Development and utilization of genome-wide InDel markers in Sorghum [Sorghum bicolor (L.) Moench

Sorghum (Sorghum bicolor L. Moench) has become an increasingly valuable crop for food, feed, and especially bioenergy feedstock production, which makes the crop extremely attractive for studying genomics and genetic diversity. Molecular markers and genomics play essential roles in sorghum breeding. The rapid development of next-generation sequencing technology has facilitated the identification of genome-wide insertion-deletion (InDel) polymorphisms, enabling the efficient construction of InDel markers that are suitable for user-friendly PCR. This study was conducted with the objective of discovering and developing InDel markers using double digest restriction site-associated DNA sequencing (ddRAD-Seq) data. A total of 19,226 InDels distributed across 10 chromosomes in the sorghum genome was identified. Of those, deletions constituted 65.7% while the remain was insertions. A comprehensive analysis of all the chromosomes revealed a total of 80 InDel sites with a minimum length of 10 bp. For a good conversion of the InDel regions to beneficial molecular markers, specific primers were designed for the amplification of 47 InDel regions that were selected for further investigation. A diverse panel of sorghum consisting of 16 accessions served a source for the developed InDel markers validation. Of the 47 InDel markers, 14 were tested across 16 sorghum accessions and were demonstrated their helpfulness for marker-assisted selection in sorghum. The polymorphic information content (PIC) values of the 16 markers varied between 0.11 and 0.38, with an average of 0.28. The findings of this study indicated that the identification of InDels and the development of molecular markers for sorghum were accomplished using the ddRAD-Seq data.

Development of polymorphic simple sequences repeats markers from whole gene resequencing data comparison of 68 Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss) is a significant cold-water fish farmed in China. Currently, most molecular marker-assisted breeding applications in rainbow trout rely on SSR markers. Although many rainbow trout SSR markers have been developed, methods for mining many polymorphic SSR markers from the genome and identifying them efficiently and rapidly are still lacking. For this reason, this study used in silico simulation method to rapidly develop a large number of polymorphic SSR markers quickly. A total of 354,613 SSR loci with two to six nucleotide repeat motifs were mined from 32 chromosomes of the rainbow trout reference genome using GMATA. The chromosome sequences of the reference genome were then aligned to the whole genome sequencing data (10×) of 68 rainbow trout samples. In silico genotyping was performed using the HipSTR programme to compare and count the variation in the number of repeats of the motifs of the SSR loci in the samples. The loci with high deletion rates and monomorphism were discarded, while those with more than one non-reference allele were kept. The final set of polymorphic SSR loci screened was 78,828. Finally, 4,821 SSR loci were selected with more than 3 alleles and no deletion in all rainbow trout samples and were physically mapped. The average polymorphic information content of these loci was 0.692, indicating high levels of polymorphism. These SSRs were utilized to analyse the genetic diversity and population structure of the 68 rainbow trout samples. The results showed that these 68 samples were divided into two groups. These newly discovered polymorphic SSR markers will provide valuable information for evaluating the construction of rainbow trout family lines for genetic diversity and improvement.

Genetic variation and structure of endemic and endangered wild celery (Kelussia odoratissima Mozaff.) quantified using novel microsatellite markers developed by next-generation sequencing.

Kelussia odoratissima Mozaff. (Apiaceae) is a native plant that has been traditionally consumed in Iran's food and pharmaceutical industries. Overharvesting of the taxon, especially at the beginning of the growing season, due to its considerable medicinal and economic value, is believed to be the main reason for the extirpating of this plant. The consequences of the severe anthropogenic impacts on the genetic diversity of populations are poorly known. In order to investigate the level of genetic variation and patterns of the genetic structure of K. odoratissima, we developed novel microsatellite markers using the 454 Roche next-generation sequencing (NGS) platform for the first time. Out of 1,165 microsatellite markers bioinformatically confirmed, twenty-five were tested, of which 23 were used to screen genetic variation across 12 natural populations. Our results showed that the average number of alleles per locus and the polymorphic information content (PIC) were 10.87 (range 7 to 27), and 0.81 (range 0.67 to 0.94), respectively. The mean observed and expected heterozygosities (± SD) across all populations were 0.80 ± 0.31 and 0.72 ± 0.14, respectively. The average pairwise FST among the populations was 0.37 (range 0.04 to 0.81). Bayesian and distance-based clustering, and principal coordinate analyses revealed at least four major genetic clusters. Although high level of structure can be explained by landscape topography and geographic distance, presence of admixed populations can be associated to seed or pollen dispersal. Contrary to expectations, the high level of genetic variation and lack of inbreeding suggest that overexploitation has not yet significantly purged the allelic variability within the natural populations in protected areas.

Ecology, genetic diversity, and population structure among commercial varieties and local landraces of Capsicum spp. grown in northeastern states of India.

Northeastern states of India are known for unique landraces of Capsicum spp. with geographical indications. However, little information is available about these valuable landraces of chillies. Surveys and collections were carried out in niche areas to find out their ecology and diversity through morphological traits and molecular analysis using microsatellite markers. Our result characterized the ecology of niche areas as cool (11.0°C-20.7°C) and humid (>60% relative humidity) climates for dalle-chilli (Capsicum annuum L.); mild-warm (12.2°C-28.6°C) and humid for king-chilli (C. chinense Jacq.); and cool to warm (11.3°C-33.1°C) and humid for bird's eye chilli (C. frutescens L.) during the crop period. The canonical correspondence analysis has shown the significant impact of temperature on the agro-morphological traits and distribution of the landraces in their niche areas. A wide variability was observed for different quantitative traits and yield attributing characters (fruit length, diameter, weight, and yield), showing high heritability (97.0%-99.0%), and genetic advance as a percentage of the mean (119.8%-434.0%). A total of 47 SSR markers used for the molecular analysis generated 230 alleles, ranging from 2 (HPMSE-7) to 10 (HPMSE-5), with an average of 4.89 alleles per locus. The average polymorphism information content was also high (0.61) and ranged from 0.20 (HPMSE-7) to 0.85 (CAMS-91). The observed average heterozygosity was lower than the expected value. Analysis of molecular variance has shown significant variation within (69%) and between (31%) of the populations of Capsicum spp. Based on Nei's genetic distance, bird's eye chilli and king-chilli were found to be closer to each other, whereas dalle-chilli, a tretraploid species, was closer to hot pepper (C. annuum). However, the flower size of dalle-chilli was large and found closer to king-chilli in color and differs from C. chinense due to the presence of calyx teeth. For quality traits, landraces king-chilli, dalle-chilli, and bird's eye chilli have shown 2.8, 2.0, and 1.4 times higher average capsaicin and 0.46, 0.25, and 0.22 times higher average oleoresin content over the hot pepper, respectively. The knowledge of ecology and diversity can be used in identifying new areas for production, selection of elite lines, conservation, and crop improvement.

Genetic diversity and morpho-physiological assessment of drought tolerance in rapeseed (Brassica napus L.) cultivars

AbstractWater deficit is one of the most important abiotic stresses constraining crop production in rapeseed. Understanding the mechanisms of adaptation to this stress is essential for the development and production of drought-tolerant genotypes. For this reason, this research study aims to investigate the importance of genetic diversity in identifying genotypes with a high degree of drought tolerance through assessing effectiveness of inter simple sequence repeat (ISSR) markers on 14 genotypes of rapeseed in a factorial design. Morphological and physiological characteristics were studied after the early stages of growth; in order to evaluate the genetic diversity among genotypes, 18 different ISSR markers were used. A total of 106 clear and scalable loci were amplified, of which 60 bands (56.6%) were polymorphic. The highest polymorphism information content belonged to marker number 9 with the amount of 0.365 (85.7%). Gene variation ranged from 0.081 to 0.365 and the rapeseed genotypes were divided into three groups by cluster analysis (unweighted pair group method with arithmetic mean method). The analysis of molecular variance showed that 70% of the total variation was observed within populations and 30% of this variation occurred among populations. In addition, t-test was used for comparing oil content percentage among different genotypes in control and stress levels. Adriana had the highest amount of seed oil with 36.47%, whereas Karaj 2 had the lowest amount with 27.28 and Cooper had the highest decrease in oil content percentage under stress conditions. Overall, the genotypes Likord, Hyola 401 and Sarigol 32 were identified as the most drought-tolerant.

Genetic diversity, population structure and marker-trait associations in Indian kale (Brassica oleracea L. gp. acephala) using cross-species microsatellite markers

Kale is known for its exceptional nourishing and functional benefits to human body. However, it is an understudied species from genomic as well as agronomic aspects. It is important to characterize niche kale germplasms around the world to systematically conserve and utilize its genetic variability, especially for commercial traits in the interest of growers, consumers and industry. With this view, genomic and phenotypic characterizations of 62 Kashmiri kale accessions including popular landraces were done to estimate and partition genetic diversity, understand trait relationships, develop population structure and divulge marker-trait associations of economic significance. Sixty-six cross species microsatellite (SSR) markers within Brassica genus amplified 269 alleles in the germplasm. Their polymorphic information content (PIC) ranged from 0.00078 to 0.953 with an average of 0.407. The population structure analysis and neighbour joining tree clustering categorized the germplasm into three sub-populations. AMOVA revealed more within-population variance (67.73 %) than among-populations (32.27 %) variance. The principal component analysis (PCA) involving 24 agronomical traits revealed seven PCs (PC1 to PC7) having Eigen values more than 1, which explained a cumulative variation of 69.21 %. Association mapping with respect to these 24 agronomical traits using mixed linear model and general linear model revealed six overlapping significant marker-trait relationships with five being significant at probability value of 0.001/0.0001. The highly significant associations of two SSRs with economically important traits (siliqua length and seed weight) significantly correlated/related with leaf yield and seed yield were revealed for their possible utilization in marker assisted breeding for higher leaf and seed yields.

Genetic diversity of Sinapis arvensis L. (wild mustard) in Türkiye determined by microsatellite markers

Wild mustard (Sinapis arvensis L.) is a self-fertilizing weed species that exerts negative impacts on wheat production and herbicides are intensively used to manage it. Cross-fertilization may lead to genetic differentiation in this species. Therefore, this study investigated genetic diversity among wild mustard populations collected from wheat fields across various regions in Türkiye. Genetic variation was evaluated using 5 simple sequence repeat (SSR) markers in populations collected from 30 different locations. Populations were analyzed using UPGMA (unweighted pair group method with arithmetic mean) and principal component analysis (PCA). The mean genetic diversity (GD) and polymorphism information content (PIC) values were 0.752 and 0.844, respectively. High genetic variability was recorded among populations within geographic locations. The populations were categorized into two major groups by UPGMA. There was no apparent geographic isolation among tested populations, which displayed a high degree of variability. The primary source of this variability is thought to be the adaptability of wild mustard seeds dispersed through various methods across diverse locations. Despite being a predominantly self-pollinating species, wild mustard may also employ some cross-pollination mechanisms. In conclusion, SSR markers proved useful in determining genetic diversity in outcrossing species, especially where no prior genotypic information is available. The study suggests that genetic diversity is maintained in wild mustard populations even with rotational farming practices and intensive use of herbicides.

Genetic variability analysis of tomato varieties using rapd markers under heat stress

Heat stress threatens agricultural and food security by reducing yield and causing plant death. The use of intra-genetic diversity in heat stress responses is a potential avenue for harnessing tolerance to climate change circumstances. This study investigated the genetic diversity of twelve tomato genotypes in Bangladesh, focusing on their suitability for summer cultivation using seven Random Amplified Polymorphic DNA (RAPD) markers. The banding patterns obtained from the PCR results were used to identify genetic differences between individuals. The RAPD markers were found to show their effectiveness in discriminating the studied lines through the computation of average Polymorphism Information Content (PIC) values, particularly focusing on dominant markers with PIC values ranging from 0 to 0.5, emphasizing the informative nature of the employed primers. Cluster analysis grouped several genotypes with possible common ancestry. Overall, BARI Hybrid Tomato 4, BARI Hybrid Tomato 8, A12, D13, and RHS1 emerged as promising candidates for further genetic research and breeding programs, particularly in the context of heat-stress conditions during summer tomato cultivation in Bangladesh. Bangladesh J. Bot. 53(1): 91-100, 2024 (March)

Molecular, morphological, palynological and biochemical characterization of six accessions of two Mangifera indica L cultivars (Keitt and Ewais) native to Egypt

AbstractAccurate characterization of crops or fruits leads to successful improvements in breeding programs. Mango (Mangifera indica L.) is the second most common fruit in Egypt. It is a heterozygous plant; consequently, the possibility of incorrect characterization is significant. Therefore, this study used six accessions of two M. indica cultivars, ‘Keitt’ and ‘Ewais’, to produce precise molecular characterization and prove their genetic relatedness using inter-simple sequence repeat (ISSR) and start codon targeted (SCoT) markers. Pollen morphology was studied for the first time for these two Egyptian cultivars to determine their correlation. Morphological traits were quantitatively and qualitatively investigated. In addition, phytochemical analyses were performed to correlate the six mango accessions. One of these accessions (accession 3) was commercially identified as ‘Ewais’ cv., but the obtained result revealed that it does not belong to ‘Ewais’ cv. This finding was proved molecularly using ISSR and SCoT markers and morphologically. Similarly, phytochemical analyses revealed a difference between accession 3 and the other accessions under investigation. Polymorphic information content (PIC) and resolving power (RP) data revealed that the SCoT technique was more informative than ISSR for studying these genotypes of mango. Accordingly, the present findings prove the necessity for molecular, morphological, palynological, and biochemical investigations for accurate characterization of mango genotypes and genetic relatedness for improving breeding programs.

Genetic polymorphism and frequency study at 15 short tandem repeat loci in the North and East Indian populations for use in personal identification and applications in India

Allele frequency is a crucial factor in estimating the weight of evidence (WoE) for an individual’s involvement in a DNA sample. To determine the allele and genotype frequencies within the populations of the northern and eastern states of India, 15 short tandem repeats (STRs) were used, including Penta E, CSF1PO, D18S51, D7S820, D21S11, TH01, D3S1358, Vwa, FGA, TPOX, D8S1179, D16S539, D13S317, Penta D, and D5S818. The study involved 509 randomly selected individuals, analyzed using the PowerPlex 16 System Kit. Various statistical parameters of forensic significance were calculated using Forensic Statistic Analysis Toolbox (FORSTAT) software, including the typical paternity index (TPI), power of exclusion (PE), matching probability (MP), power of discrimination (PD), polymorphism information content (PIC), and observed (Hobs) and expected heterozygosities (Hexp). The analysis revealed a maximum allele frequency of 0.4282 at TPOX, with a minimum frequency of 0.0009 observed at different loci. FGA was found to be the most polymorphic loci among the 15 loci analyzed in the North and East Indian populations. Furthermore, no divergence from the Hardy‐Weinberg equilibrium (HWE) was observed. The results serve as a valuable source of information for establishing a DNA database for North and East Indian populations, providing essential information for population genetics studies and forensic casework in India.

Development of Novel Genomewide Simple Sequence Repeat Markers for Acer truncatum Bunge and Assessment of Their Transferability to Other Closely Related Species

Acer truncatum Bunge is a versatile woody tree species with high economic and medicinal value in the production of bioactive substances and unsaturated fatty acids (especially nervonic acid). However, the exploitation and evaluation of A. truncatum germplasm resources are limited owing to a lack of sound molecular marker systems. In this study, a large set of genomewide simple sequence repeat (SSR) markers of A. truncatum was developed based on its whole-genome sequences. A total of 462,331 SSR loci were identified in the genome sequences, 99.3% (459,193) of which were located on 13 chromosomes. The chromosome length was significantly positively correlated with the number of SSR loci on the chromosome (r = 0.977, p < 0.001). The (A/T)n, (AT/TA)n, and (AAT/ATT/TAA/TTA/TAT/ATA)n were the most frequent motifs for mono-, di-, and trinucleotide repeat motifs, respectively, showing A/T-base bias. After BLASTN and electronic polymerase chain reaction (PCR) analyses, 199,990 loci with specific physical positions were screened. Most of the SSR loci were located in the intergenic regions and fewest in the coding sequences (CDSs). The frequency of loci with tri- and hexanucleotide repeat motifs was the highest in the CDSs, potentially serving to maintain the stability of gene function and structure. In randomly selected 105 SSR markers, 82 (78.1%) showed allelic polymorphism, with polymorphism information content (PIC) values of 0.032–0.926 (0.481 on average). The SSRs in the noncoding regions exhibited significantly higher PIC values than those in the CDSs. The transferability of the 105 markers was 48.6%–59.0% to seven other Acer species. The large set of valid SSR markers provides a powerful tool for studies on population genetics, conservation genetics, linkage mapping, comparative genomics, and marker-assisted breeding of the genus Acer.

Genetic diversity analysis of banana using SSR markers

Banana, a crucial fruit crop thriving in tropical and sub-tropical regions, facing a notable challenge of elevated sterility across various cultivated banana genotypes. This sterility issue hampers the cultivation of diverse banana varieties. Therefore, a focused endeavour is crucial to thoroughly investigate the richness of diversity within both wild and cultivated banana genotypes, aiming to preserve it for future utilization. In the present study, 21 Musa genotypes were collected from different places of North-Eastern Region, and conserved in the field gene bank at Department of Horticulture, College of Agriculture, Lembucherra, Tripura during 2015-2022. Molecular characterization and DNA fingerprinting of these banana accessions were performed by employing 16 banana SSR markers. The number of alleles per locus ranged from 15 to 24 with an average 20.375. The expected heterozygosity (He) ranged from 0.564-0.967 with a mean of 0.852, and the polymorphic information content (PIC) varies from 0.638–0.945 (mean = 0.859). Genetic diversity analysis showed dissimilar groups, indicating possibility of involvement of different accuminata and balbisiana types in evaluation of banana in NE region. The outcome of the current study will be useful for des igning banana crops against different stresses

Genetic Diversity in Katchaikatty Sheep based on Microsatellites Polymorphism

Background: Sheep is one of the important species of livestock in India contributing to meat production. India has 44 distinct breeds of sheep, out of which 10 are found in Tamil Nadu. The present study describes the molecular characterization of recently registered breed of sheep - Katchaikatty sheep, genetic variability and genetic structure of the population by microsatellite marker analyses. Methods: DNA from 50 unrelated Katchaikatty sheep was amplified with 25 FAO recommended fluorescent tagged ovine-specific microsatellite markers and genotyped on an automated Genetic Analyzer. In each locus, observed (no) and effective number of microsatellite alleles (ne), allele frequencies, observed (Ho) and expected (He) heterozygosity and heterozygosity deficit estimate (FIS), polymorphism information content (PIC) and Chi-square (χ2) test for Hardy-Weinberg equilibrium (HWE) were assessed. Mode-shift analyses were performed. Result: The study revealed a total of 144 alleles across all the loci. The number of alleles at each locus varied from one to 10 with a mean of 5.76 alleles. The PIC values in the microsatellite loci ranged from 0.34 (OarAE129) to 0.83 (OarFCB48) with an average of 0.59, which showed a high genetic polymorphism. Six out of 25 microsatellite loci studied were in Hardy-Weinberg equilibrium and 19/25 loci showed positive FIS values. The overall mean observed and expected heterozygosity were 0.50 and 0.65 respectively and the estimates elucidated a substantial genetic variability in Katchaikatty sheep population. Mode shift analysis revealed a normal L-shaped curve, describing that the Katchaikatty population had not experienced any genetic bottleneck and remained in mutation-drift equilibrium.

Growth performance and selection signatures revealed by whole-genome resequencing in genetically selected grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella) is a highly productive freshwater fish species that is widely cultivated worldwide, contributing substantial economic value to the aquaculture industry annually. Recently, a breeding program for grass carp has progressed to the fourth generation (F4) after four consecutive generations of family selection. To further assess the growth performance of the genetically selected grass carp F4, a 90-day consecutive growth comparison experiment was conducted between the selected population and a wild base population. The results showed that the selected grass carp F4 had better growth performance. Whole-genome resequencing of both wild and selected populations of grass carp yielded a total of 4,354,416 high-quality single nucleotide polymorphisms (SNPs). Parameters of genetic diversity including observed heterozygosity (Ho), expected heterozygosity (He), nucleotide diversity (π), and polymorphic information content (PIC) were slightly decreased in the selected population compared to the wild population. The fixation index (Fst) indicated a low level of genetic differentiation (Fst = 0.021). Selection signatures analysis identified a total of 173 candidate selected regions with a cumulative size of 23.75 Mb, and 912 candidate genes including igf-1r, igfbp-2, igfbp-5 and itga6. This study provides valuable insights into the growth performance and the genetic basis of selection signatures in the process of grass carp selective breeding, and offers guidance for future breeding programs.

Development and characterization of 40 InDel markers from the major histocompatibility complex genes of largemouth bass (Micropterus salmoides).

The genetic improvement in growth and food habit domestication of largemouth bass (Micropterus salmoides) have made breakthroughs in past decades, while the relevant work on disease resistance were rarely carried out. Major histocompatibility complex (MHC) genes, which are well known as their numbers and high polymorphisms, have been used as candidate genes to mine disease-resistant-related molecular markers in many species. In present study, we developed and characterized 40 polymorphic and biallelic InDel markers from the major histocompatibility complex genes of largemouth bass. The minor allele frequency, observed heterozygosity, expected heterozygosity and polymorphic information content of these markers ranged from 0.0556 to 0.5000, 0.1111 to 0.6389, 0.1064 to 0.5070, and 0.0994 to 0.3750, respectively. Three loci deviated significantly from Hardy-Weinberg equilibrium, while linkage disequilibrium existed at none of these loci. These InDel markers might provide references for the further correlation analysis and molecular assisted selection of disease resistance in largemouth bass.

Molecular Genetic Diversity of Manioc (Manihot esculenta Crantz) Using Simple Sequence Repeated Markers (SSR) in the Kara Region of Togo

Cassava (Manihot esculenta Crantz), a plant of the future, is one of the main crops with high genetic potential. Therefore, the knowledge of its genetic variability would be of great importance for its effective use in genetic improvement programs. The objective of this work was to characterize the genetic diversity of cassava cultivars present in the Kara region of Togo. Thus, a total of 91 cassava leaf samples collected in the 7 prefectures of the Kara region were analyzed using 7 pairs of SSR microsatellite primers. Fifty-three alleles were detected with an average of 7.57 alleles per locus. The polymorphic information content ranged from 0.63 to 0.83 with an average of 0.74, indicating a high level of marker polymorphism. Molecular analysis of variance revealed that the majority of variability occurred within individuals and accounted for 99 % of the total variation between individuals. Weak genetic differentiation (Fst=0.011) was also observed between populations. The genetic structuring model based on the Neighbour-Joining algorithm method divided the individuals into 6 groups independently of local names. These results indicate the presence of high genetic resource variability in the studied populations. Therefore, it would be important to implement management strategies to better conserve cassava genetic resources and to facilitate the identification of successful cultivars.