Species-specific Molecular Markers Research Articles

Genetic and Morphological Analysis of the Origin and Identity of Perennial Lavatera (Malvaceae) Cultivars

Knowledge of the origin of Lavatera L. (tree mallows) cultivars helps to predict their cultural requirements. Eighteen accessions representing 15 cultivars, 14 accessions of 7 species, and 5 accessions of an F1 hybrid between the putative parents of the cultivars were sampled for morphological variation and for randomly amplified polymorphic DNA (RAPD) fingerprint variation. Species-specific molecular markers were identified from the RAPD profiles. Chimeral elements were not distinguishable by RAPD analysis. Principal component analysis identified the majority of the cultivars to be selections of hybrid origin, probably from a narrow genetic base. Two cultivars were derived directly from individual species. The resolving power of RAPD markers and morphology was similar although RAPD data offered greater ability to ascribe parentage while morphology offered optimal discrimination of cultivar selections.

Presence of double-stranded RNAs in human and calf isolates of Cryptosporidium parvum.

We examined the occurrence of 2 virus-like double-stranded (ds)RNAs in human and calf isolates of Cryptosporidium parvum senso latu and other microorganisms, including 7 other members of the genus. A total of 32 isolates of C. parium, 16 from humans (5 from acquired immune deficiency syndrome patients) and 16 from calves, were analyzed. Ethidium bromide staining, or Northern blot analysis, or reverse transcription/polymerase chain reaction, or all 3 methods, revealed that both genotype 1 and genotype 2 isolates of C. parvum possessed these dsRNAs. No other Cryptosporidium spp. or other organisms examined possessed these dsRNAs. Comparison analysis of partial cDNA sequences of dsRNAs from human and calf isolates revealed a high degree of similarity (>92% and >93% identical nucleotides for large and small dsRNAs, respectively). Slight, consistent differences in nucleotide sequences could be seen at select sites and were associated with an isolate being either genotype 1 or 2. Because of the widespread distribution of the dsRNAs, the similarity of these molecules between isolates, and high host specificity, these nucleic acids may prove to represent species-specific molecular markers for C. parvum. Evidence also suggests that the dsRNA can be utilized for molecular genotyping of C. parvum.

Morphological analysis of genetically identified cattails Typha latifolia, Typha angustifolia, and Typha ×glauca

Hybridization between the cattail species Typha latifolia L. and Typha angustifolia L. is frequent throughout northeastern and central North America. While studies are required to elucidate the ecological role of interspecific hybrids, morphological intergradation of the hybrids and parental species limits accurate identification. Although species-specific molecular markers have been developed, some researchers do not have the resources necessary for molecular analysis. Consequently, this study used genetically identified specimens of T. latifolia,T. angustifolia, and their hybrid Typha ×glauca Godr. to discriminate sound taxonomic characters for morphological identification. Leaf width, spike gap, spike width, and spike length were measured for 153 specimens of cattails from Massachusetts, Ontario, Quebec, and Manitoba. In addition, stigma width was measured using a compound microscope. Morphological data were used in discriminant analysis; approximately 90% of the classifications derived by discriminant analysis corresponded to the genetic identity. Discriminant analysis using stigma width, spike length, spike interval and leaf width provided accurate identification for 28 of 31 T. angustifolia specimens, 38 of 41 T. ×glauca specimens, and 20 of 25 T. latifolia specimens. Thus, discriminant analysis of morphological characters can be used to distinguish the hybrid cattail from the parental species with reasonable confidence when molecular resources are not available.Key words: Typha, cattails, discriminant analysis, DNA markers.

Morphological analysis of genetically identified cattails <i>Typha latifolia</i>, <i>Typha angustifolia</i>, and <i>Typha קlauca</i>

Hybridization between the cattail species Typha latifolia L. and Typha angustifolia L. is frequent throughout northeastern and central North America. While studies are required to elucidate the ecological role of interspecific hybrids, morphological intergradation of the hybrids and parental species limits accurate identification. Although species-specific molecular markers have been developed, some researchers do not have the resources necessary for molecular analysis. Consequently, this study used genetically identified specimens of T. latifolia, T. angustifolia, and their hybrid Typha ×glauca Godr. to discriminate sound taxonomic characters for morphological identification. Leaf width, spike gap, spike width, and spike length were measured for 153 specimens of cattails from Massachusetts, Ontario, Quebec, and Manitoba. In addition, stigma width was measured using a compound microscope. Morphological data were used in discriminant analysis; approximately 90% of the classifications derived by discriminant analysis corresponded to the genetic identity. Discriminant analysis using stigma width, spike length, spike interval and leaf width provided accurate identification for 28 of 31 T. angustifolia specimens, 38 of 41 T.× glauca specimens, and 20 of 25 T. latifolia specimens. Thus, discriminant analysis of morphological characters can be used to distinguish the hybrid cattail from the parental species with reasonable confidence when molecular resources are not available.

Diversity analysis and species identification in Lens using PCR generated markers

Using random amplified polymorphic DNA (RAPD) analysis we assessed the genetic relationships between 16 accessions and cultivars of lentil (Lens culinaris ssp. culinaris) in the Australian lentil breeding program. All lines exhibited polymorphism with a maximum dissimilarity value of 0.36. This indicated a limited degree of genetic variation. Polymerase chain reaction (PCR) with primers based on the flanking regions of the 5S rRNA gene from Pisum sativum amplified the non-translated spacer (NTS) region from within the 5S rRNA gene of Lens. Three distinct amplification banding patterns differentiated between restricted genomic DNA of Lens spp. L. culinaris ssp. culinaris and L. culinaris ssp. orientalis shared similar markers of two distinctly different NTS sizes. L. nigricans and L. odemensis shared the same amplification pattern of a single sized NTS region. However, L. ervoides contained two separate sizes of NTS, distinct from other Lens species. In an effort to widen the genetic base of cultivated lentil, these species-specific molecular markers may be used to follow potential introgression between species.

The Origin of GregariousMuscidifurax(Hymenoptera: Pteromalidae) in North America: An Analysis Using Molecular Markers

Parasitic wasps of the genus Muscidifurax (Hymenoptera: Pteromalidae) are pupal parasitoids of various diptera and are important biological control agents of flies that breed in accumulated animal wastes and garbage. Most species of Muscidifurax, including both North American species Muscidifurax raptor and Muscidifurax zaraptor, oviposit a single egg on each host (solitary oviposition). Recent collections in the central United States, however, have revealed populations of Muscidifurax with gregarious oviposition. Previously, the only known gregarious Muscidifurax was the South American species Muscidifurax raptorellus, which is gregarious in Chile but solitary in Peru. We have developed species-specific molecular markers for the genus Muscidifurax by RAPD–PCR and have used these markers to identify the origin of gregariousness in North America. Banding patterns from three of four primers clearly distinguished M. raptor, M. zaraptor, and M. raptorellus, and those from the gregarious North American population most closely resembled those of South American M. raptorellus. We conclude that the appearance of gregarious oviposition in central North America resulted from the introduction of gregarious M. raptorellus, rather than a novel development of gregariousness within existing populations of M. raptor or M. zaraptor. Gregarious Muscidifurax are very aggressive in the laboratory and are effective biological control agents, but how they interact with other parasitoid species that attack dipteran pupae in the field remains unknown.

Species-specific RAPD fingerprints for the closely related Picea mariana and P. rubens

Species-specific molecular markers were designed to assist in the identification of closely related black spruce (Picea mariana [B.S.P.] Mill.) and red spruce (P. rubens Sarg.) in northeastern North America. Trees from six provenances of black spruce and three provenances of red spruce were sampled from outside the sympatric zone. They were first classified using a composite index of five qualitative morphological traits. The species-specific genetic markers were developed using random amplified polymorphic DNAs (RAPD) and a combination of bulk sample and individual tree analyses. Each species bulk sample was constructed from DNAs obtained from 12 trees that were from outside the sympatric zone and showed a morphological composite index specific of each species. A total of 161 primers were screened with the bulk samples. From these, 52 primers showing segregating fingerprints were further screened with the individual trees. Most of the markers observed were shared by the two species, and there was less diversity in P. rubens. A small number of markers were found to be monomorphic or nearly monomorphic and specific to either P. mariana or P. rubens. These markers remained species-specific when F1 progenies derived from independent intraspecific crosses were screened, and they were subsequently found to co-segregate in hybrids derived from independent interspecific crosses here used as controls.