Transferability of Sorghum Microsatellite Markers to Bamboo and Detection of Polymorphic Markers

The use of molecular markers for the characterization and evaluation of plant genetic resources has become a useful approach in plant genetic research. Simple Sequence Repeats (SSRs) are among the markers that are widely used in genetic diversity and parental analysis owing to their co-dominant nature, high reproducibility, abundance in the genome and transferability across species or genera. The development of these markers for a species might be costly and time consuming. Hence, screening existing markers through transferability test from closely related species or family is resource conscious. In this study, the transferability of 90 polymorphic SSR markers of sorghum to bamboo was tested and polymorphic analysis of transferable markers were performed. Nearly 62% of the tested SSRs successfully recorded amplification in at least one bamboo species of which 55% were polymorphic. These polymorphic markers detected a total of 147 alleles at an average rate of 4.7 alleles per marker. The abundant alleles account 20.4% while the common and rare alleles share 39.6 and 40 %, respectively. The result showed a relatively low degree of polymorphic information content (PIC) averaging 0.29. The gene diversity index (He) ranged from 0.21 to 0.49 with a mean of 0.37. The cluster analysis based on the polymorphic markers surfaced most of the species in accordance with their geographic origin. The complementarity of the weighted neighbour joining tree and coordinate analysis implies the representative nature of the transferred markers for the diversity analysis of bamboo species.

Predominant paternal inheritance pattern of light-energy processing adaptive traits in red and black spruce hybrids

Ecophysiological traits related to light-energy processing and freezing tolerance are important adaptive traits in plants. Our goal was to investigate the pattern of inheritance of these traits in hybrids using controlled intra- and inter-specific crosses of red spruce ( Picea rubens Sarg.) (RS) and black spruce ( Picea mariana (Mill.) BSP) (BS). Our initial working hypothesis was that expected hybrid index categories could be a predictor of adaptive traits. Species results of dark-adapted photochemical efficiency (Fv/Fm) and light-adapted light-energy processing traits, quantum yield (YLD), thermal dissipation efficiency (qN), and chlorophyll fluorescence (Fpc), were consistent with previously published open-pollinated, species provenance results. Initially, YLD, qN, and Fpc, showed an additive inheritance pattern, evident by average hybrid index 50 having a mid-parent value. Because of various crosstypes of the hybrid families, parental analysis, testing male, female, and interaction effects, and having three categories (pure RS, pure BS, and hybrid spruce), revealed significant male and nonsignificant female and interactive effects. Underlying the averaged additive results was a significant species-specific paternal inheritance pattern. Crosses with BS males had 13.7% higher YLD (P = 0.001), 15.4% lower qN (P = 0.008), and 43.0% higher Fpc (P = 0.096) than crosses with either RS or hybrid males. Fv/Fm showed a nonadditive or parental species pattern. Parental analysis of Fv/Fm showed significant male, female, and male × female interaction effects, and further analysis supports a largely species-specific and paternally inherited trait. Freezing tolerance revealed a mixed model of inheritance dominated by species effects. Total dry mass was positively correlated with YLD, and negatively correlated with Fv/Fm and qN, suggesting a biological tradeoff. We know of no other studies in trees demonstrating paternal inheritance of ecophysiological processes that affect adaptation and fitness.

Comparison of Microsatellite and Single Nucleotide Polymorphism Markers for the Genetic Analysis of a Galloway Cattle Population

Highly informative genetic markers are essential for efficient management of cattle populations, as well as for food safety. After a decade of domination by microsatellite markers, a new type of genetic marker, single nucleotide polymorphism (SNP), has recently appeared on the scene. In the present study, the exclusion power of both kinds of markers with regards to individual identification and parental analysis was directly compared in a Galloway cattle population. Seventeen bovine microsatellites were distributed in three incremental marker sets (10, 14 and 17 microsatellite markers) and used for cattle genotyping. A set of 43 bovine SNP was used for genotyping the same cattle population. The accuracy of both kinds of markers in individual identification was evaluated using probability of identity estimations. These were 2.4 × 10-8 for the 10 microsatellite set, 2.3 × 10-11 for the 14 microsatellite set, and 1.4 × 10-13 for the 17 microsatellite marker set. For the 43 SNP markers, the estimated probability of identity was 5.3 × 10-11. The exclusion power of both kinds of markers in parental analysis was evaluated using paternity exclusion estimations, and, in addition to this, by estimation of the parental exclusion probability in 18 Galloway family trios. Paternity exclusion was estimated to be over 99% for microsatellites, and approx. 98% for SNP. Both, microsatellite and SNP sets of markers showed similar parental exclusion probabilities.

Sweetpotato Genome Fingerprinting and Parental Analysis Using Microsatellites.

Microsatellites or simple sequence repeats (SSRs) were used to characterize 20 sweetpotato genotypes and to assign paternity for offspring from crosses among them. The PCR amplifications were performed with each of the sweetpotato genotypes and primers flanking a SSR loci previously characterized with the varieties Beauregard and Excel and 20 offspring from a cross among them. The PCR reaction products were separated in nondenaturing 12% acrylamide gels run at 25 V·cm–1 for 5 hours, and DNA fragments were visualized with silver staining. Gels were scanned on a flat bed scanner and analyzed using the Pro-RFLP software package. Three primer pairs were sufficient to produce an allelic profile capable of differentiating the 20 genotypes from each other. More than seven alleles/loci were found using each of the three primer pairs assayed. Occasionally primers produced allelic products clearly localized in two or three regions of the gel. These multiple loci segregated independently in a diploid fashion. This evidence suggests that there is not total homology among the three sweetpotato genomes.