Genetic diversity and marker trait association for yellow mosaic virus disease in green gram, Vigna radiata (L.) Wilczek

Yellow mosaic virus (YMV) disease is known to cause severe damage in green gram in terms of yield loss. As the resistance is often governed by recessive genes, introgression of such resistance faces some difficulty. DNA molecular markers are reported to be effective in this process. However, validation of such markers is important. Here, we have made an attempt to validate DNA markers associated with YMV disease resistance gene from a diverse group of 26 green gram genotypes. A total of 19 molecular markers were used to assess the susceptibility or resistance against YMV disease. Results show that among the amplified 31 alleles, 21 were polymorphic, with a mean of 1.1.0 per locus. The polymorphism information content (PIC) values ranged from 0.32 to 0.80. Only five markers exhibited higher PIC value (>6.0) and were revealed to be polymorphic, suggesting its utility in marker assisted selection for breeding YMV resistant genotypes in greengram. Dice dissimilarity coefficient among the genotypes exhibited a range of 0.07 to 1.0 which show a wide genetic variation among the genotypes for YMV tolerance. Neighbor-joining cluster analysis has grouped 26 green gram genotypes into 4 main clusters which revealed the existence of genetic dissimilarities among the genotypes. The genotypes AUGG 6, VBN (Gg) 2 and CO (Gg) 8 carried the positive alleles for YMV disease resistance and the allele for susceptibility were found in the genotypes AUGG 12, AUGG 15, AUGG 17 and AUGG 19. Single marker analysis indicated that there was correlation between the markers and the disease reaction in the field with exceptions. The findings revealed that the SSR markers CEDG180 and YR4 could be used to screen germplasm in order to discriminate the YMV resistant genotypes from the susceptible genotypes in marker assisted selection.

Evaluación de la utilidad de marcadores microsatélites en la población avícola rustipollos / Evaluation of the utility of microsatellite markers in the poultry population rustipollos

RESUMEN Los marcadores moleculares son una herramienta de gran utilidad para estudios de diversidad genética, que permite identificar poblaciones con características genéticas particulares, que soportan el establecimiento de programas de conservación y mejoramiento genético. El objetivo de este estudio fue evaluar el grado de información generada por un panel de 30 marcadores microsatélites en la población avícola Rustipollos. Se obtuvieron muestras de sangre de 50 individuos, la amplificación de fragmentos se realizó mediante PCR, utilizando 30 microsatélites recomendados por la FAO-ISAG para estudios de biodiversidad en gallinas. La estimación de los tamaños de los fragmentos se realizó en un secuenciador automático ABI Prism 377. Fueron determinados el número de alelos por locus y el Contenido de Información Polimórfica (PIC), mediante el programa Microsatellite-Toolkit. El número total de alelos reportados fue de 99 en los 30 marcadores microsatélites, con un valor medio de 3.3 ±1.06 alelos por locus. La determinación del PIC registró un promedio de 0.46, con un rango de 0.18 a 0.76 en los marcadores MCW016 y ADL278, respectivamente. El 43% de los marcadores empleados resultaron altamente informativos para la población evaluada. En general, los marcadores microsatélites demostraton ser útiles para estudios genéticos en la población avícola Rustipollos.

ABSTRACT Molecular markers are a very useful tool for genetic diversity studies, allowing the identification of populations with particular genetic characteristics, in order to establish conservation and genetic improvement programs. The objective of this study was to evaluate the degree of information generated by a panel of 30 microsatellite markers in the Rustipollos poultry population. Blood samples were obtained from 50 individuals, the fragments were amplified by PCR, using 30 microsatellites recommended by FAO-ISAG for biodiversity studies in chickens. The estimation of the fragment sizes was carried out in an ABI Prism 377 automatic sequencer. The number of alleles per locus and the Polymorphic Information Content (PIC) were determined using the Microsatellite-Toolkit program. The total number of alleles reported was 99 in the 30 microsatellite markers, with a mean value of 3.3 ± 1.06 alleles per locus. The PIC determination registered an average of 0.46, with a range of 0.18 to 0.76 in the MCW016 and ADL278 markers, respectively. 43% of the markers used were highly informative for the population evaluated. In general, microsatellite markers proved to be useful for genetic studies in the Rustipollos poultry population.

Analysis of the genetic relationships and diversity among 11 populations of Xanthoceras sorbifolia using phenotypic and microsatellite marker data

Background: Assessments of genetic diversity are essential for germplasm characterization and exploitation. Molecular markers are valuable tools for exploring genetic variation and identifying germplasm. They play key roles in a Xanthoceras sorbifolia breeding program. Results: We analyzed the genetic diversity of populations of this species using 23 simple sequence repeat (SSR) loci and data on kernel oil content. The 11 populations included in the study were distributed across a large geographic range in China. The kernel oil content differed significantly among populations. The SSR marker analysis detected high genetic diversity among the populations. All SSRs were polymorphic, and we identified 80 alleles across the populations. The number of alleles at each locus ranged from two to six, averaging 3.48 per primer pair. The polymorphism information content values ranged from 0.35 to 0.70, averaging 0.51. Expected heterozygosity, observed heterozygosity, and Shannon's information index calculations detected large genetic variations among populations of different provenance. The high average number of alleles per locus and the allelic diversity observed in the set of genotypes analyzed indicated that the genetic base of this species was relatively wide. The statistically significant positive correlation between genetic and geographic distances suggested adaptations to local conditions. Conclusions: Microsatellite markers can be used to efficiently distinguish X. sorbifolia populations and assess their genetic diversity. The information we have provided will contribute to the conservation and management of this important plant genetic resource.

Discerning non-disjunction in down syndrome patients by means of GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21.

Introduction: Down syndrome (DS), the leading genetic cause of mental retardation, stems from non-disjunction of chromosome 21. Aim: Our aim was to discern non-disjunction in DS patients by genotyping GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21 using a family-based study design. Materials and Methods: We have used a PCR and automated DNA sequencing followed by appropriate statistical analysis of genotype data for the present study Results and Discussion: We show that a high power of discrimination and a low probability of matching indicate that both markers may be used to distinguish between two unrelated individuals. That the D21S2055-(GATA) n allele distribution is evenly balanced, is indicated by a high power of exclusion [PE=0.280]. The estimated values of observed heterozygosity and polymorphism information content reveal that relative to GluK1-(AGAT) n [H obs =0.286], the D21S2055- (GATA) n [H obs =0.791] marker, is more informative. Though allele frequencies for both polymorphisms do not conform to Hardy-Weinberg equilibrium proportions, we were able to discern the parental origin of non-disjunction and also garnered evidence for triallelic (1:1:1) inheritance. The estimated proportion of meiosis-I to meiosis-II errors is 2:1 in maternal and 4:1 in paternal cases for GluK1-(AGAT) n , whereas for D21S2055-(GATA) n , the ratio is 2:1 in both maternal and paternal cases. Results underscore a need to systematically evaluate additional chromosome 21-specific markers in the context of non-disjunction DS.