Isolation and Characterization of Microsatellites Markers in Centaurium Grandiflorum ssp. Boissieri

Estimation of outcrossing/selfing rates and characterization of genetic diversity with microsatellite markers are crucial to understand the evolution of mating system in plant species. We developed, optimized and characterized eight new primers pairs for Centaurium grandiflorum ssp. boissieri and transferred them to three subspecies of Centaurium quadrifolium. Two SSR loci were transferred from Sabatia campestris to the four mentioned taxa of Centaurium. Polymorphisms, He, Ho and H-W deviations were estimated in two populations of C. grandiflorum ssp. boissieri, and in seven individuals of C. quadrifolium ssp. barrelieri, C. quadrifolium ssp. parviflorum and C. quadrifolium ssp. quadrifolium. A total of 80 individuals were used in these experiments. The number of polymorphic loci varied among species from one to ten. A total number of 127 alleles were scored. The average number of alleles per locus was 12.7. He was higher than Ho in all sampled populations. Hardy-Weinberg equilibrium was found for some loci in different species. This is the first report of microsatellites successfully amplified in the whole Centaurium genus. They will be valuable for estimation of mating system parameters, genetic diversity and explore its relationship with the wide flower morphology, especially anther-stigma separation, found along the genus.

Genetic Diversity Study of African Rice (Oryza glaberrima) and its Wild Relatives using Microsatellites Markers

The Africa Rice Center Gene Bank hold about 2,500 accessions of Oryza glaberrima. To understand well the genetic diversity in O. glaberrima and its wild species, the use of molecular tools is prominent. The sample consisted of 217 accessions of O. glaberrima, 46 of O. barthii and 7 of O. sativa (checks) was genotyped with 21 polymorphic microsatellites markers. A total of 245 alleles were detected with average 11.67 alleles per locus. Number of alleles was ranged from 2 (RM124) to 20 (RM536). The polymorphic information content value was 0.49 while the heterozygosity was 0.091. The result showed that the sample can be clustered into four genotypic groups. Two groups among them were homogeneous. The first one consisted of O. barthii accessions with 82 alleles in total with average 3.90 alleles per locus. However, the second one consisted of only O. glaberrima accessions with 122 alleles with average 5.80 alleles per locus. O. glaberrima accessions were analyzed using model-based population structure. Results revealed two groups among O. glaberrima accessions. At the end, the identified core collection has 26 accessions consisted of 16 O. glaberrima and 10 O. barthii based on 21 microsatellites markers.

Temporal migration rates affect the genetic structure of populations in the biennial Erysimum mediohispanicum with reproductive asynchrony

Migration is a process with important implications for the genetic structure of populations. However, there is an aspect of migration seldom investigated in plants: migration between temporally isolated groups of individuals within the same geographic population. The genetic implications of temporal migration can be particularly relevant for semelparous organisms, which are those that reproduce only once in a lifetime after a certain period of growth. In this case, reproductive asynchrony in individuals of the same population generates demes of individuals differing in their developmental stage (non-reproductive and reproductive). These demes are connected by temporal migrants, that is, individuals that become annually asynchronous with respect to the rest of individuals of their same deme. Here, we investigated the extent of temporal migration and its effects on temporal genetic structure in the biennial plant Erysimum mediohispanicum. To this end, we conducted two independent complementary approaches. First, we empirically estimated temporal migration rates and temporal genetic structure in four populations of E. mediohispanicum during three consecutive years using nuclear microsatellites markers. Second, we developed a demographic genetic simulation model to assess genetic structure for different migration scenarios differing in temporal migration rates and their occurrence probabilities. We hypothesized that genetic structure decreased with increasing temporal migration rates due to the homogenizing effect of migration. Empirical and modelling results were consistent and indicated a U-shape relationship between genetic structure and temporal migration rates. Overall, they indicated the existence of temporal genetic structure and that such genetic structure indeed decreased with increasing temporal migration rates. However, genetic structure increased again at high temporal migration rates. The results shed light into the effects of reproductive asynchrony on important population genetic parameters. Our study contributes to unravel the complexity of some processes that may account for genetic diversity and genetic structure of natural populations.

Behavioral Genetics of the Interactions between Apis mellifera and Varroa destructor

The western honeybee Apis mellifera exhibits a diverse set of adaptations in response to infestations by its most virulent disease-causing agent, the ectoparasitic mite Varroa destructor. In this study, we investigated the effect of honeybee pupae genotype on the expression of four host and parasite traits that are associated with the reproductive phase of the mite in the brood of its host. We first phenotyped cells containing bee pupae to assess their infestation status, their infestation level, the reproductive status of the mites, and the recapping of cells by adult workers. We then genotyped individual pupae with five microsatellites markers to compare these phenotypes across full sister groups. We found that the four phenotypes varied significantly in time but did not across the subfamilies within the colonies. These findings show that V. destructor mites do not differentially infest or reproduce on some particular honeybee patrilines, and that workers do not target preferentially specific pupae genotypes when performing recapping. These findings bring new insights that can help designing sustainable mite control strategies through breeding and provide new insights into the interactions between A. mellifera and V. destructor.