ISOZYME POLYMORPHISM AND GENETIC STRUCTURE OF MALUS SYLVESTRIS (L.) MILL. NATIVE IN WESTERN AREAS OF GERMANY WITH RESPECT TO MALUS X DOMESTICA BORKH.

Malus sylvestris, the only Malus species native to Central Europe, is considered to be very rare and endangered.
One major obstacle to the development of conservation strategies for the protection of this native fruit tree is the lack of knowledge about its natural genetic diversity and the possible influence of introgression of alleles from Malus x domestica. Isozymes continue to be among the most commonly used markers for investigations of genetic diversity in forest trees.
This technique was employed to determine the genetic structure of 202 trees representing M. sylvestris from different regions in western Germany.
These results were compared to similar data on 321 old and new cultivars of M. x domestica. Twelve isozyme loci/zones from the enzyme systems GPI, TPI, AAT, PGM, DIA, 6PGD, and MDH were investigated in fresh leaf samples.
Genetic parameters were calculated on the basis of allele frequencies of nine polymorphic loci within different Malus groups.
The various gene pools differ in their mean number of alleles per locus (A/L) and genotypes per locus (G/L), mean heterozygosity (H_a and H_c), total differentiation (_T), and diversity (v). Most loci show major polymorphism.
The most important result is the relatively high genic distance (d₀) between M. sylvestris and M. x domestica that ranges from 0.30 to 0.45, depending on the gene pools compared.
Introgression can be observed, but the results of this study indicate that gene flow in either direction has been minimal.

XI Eucarpia Symposium on Fruit Breeding and Genetics

I. Wagner, H.P. Schmitt, W. Maurer, U. Tabel

apples, allele frequencies, diversity, heterozygosity, genetic distance, introgression, genetic resources

https://doi.org/10.17660/ActaHortic.2004.663.95