Browsing by Author "Pandey, M."

Sycamore (Acer pseudoplatanus L.) is a tetraploid European hardwood tree species. The reproduction system of the insect-pollinated trees and patterns of genetic variation are largely unknown. We isolated and characterized eight polymorphic microsatellite markers for Acer pseudoplatanus L. The high degree of polymorphism observed at these markers makes them useful to observe genetic variation patterns at various spatial scales and to analyse gene flow and the mating system. Primers developed for the amplification of microsatellites in A. pseudoplatanus were tested for 21 different species of genus Acer. Amplification products of the expected size were obtained in most cases.

Allozyme and PCR-based molecular markers have been widely used to investigate genetic diversity and population genetic structure in autotetraploid species. However, an empirical but inaccurate approach was often used to infer marker genotype from the pattern and intensity of gel bands. Obviously, this introduces serious errors in prediction of the marker genotypes and severely biases the data analysis. This article developed a theoretical model to characterize genetic segregation of alleles at genetic marker loci in antotetraploid populations and a novel likelihood-based method to estimate the model parameters. The model properly accounts for segregation complexities due to multiple alleles and double reduction at antotetrasomic loci in natural populations, and the method takes appropriate account of incomplete marker phenotype information with respect to genotype due to multiple-dosage allele segregation at marker loci in tetraploids. The theoretical analyses were validated by making use of a computer simulation study and their utility is demonstrated by analyzing microsatellite marker data collected from two populations of sycamore maple (Acer pseudoplatanus L.), an economically important autotetraploid tree species. Numerical analyses based on simulation data indicate that the model parameters can be adequately estimated and double reduction is detected with good power using reasonable sample size.

We investigated five population pairs of Dalbergia sissoo in Nepal for variation of cpDNA and at the isozyme gene locus Gdh-A. Each population pair consisted of one natural population and a neighboring plantation. Two or three different cpDNA-haplotypes were observed in each population with a total of eight different haplotypes. The differentiation of cpDNA haplotypes between the group of natural populations and the group of plantations was almost complete. Thus, the plantations did not originate from any of the investigated natural populations, but reproductive material was transported over long distances during plantation establishment. All plantations proved to be fixed at the Gdh-A gene locus, which showed considerable polymorphism in natural populations indicating different adaptive potentials of plantations and natural stands.