Zhuk, A., Veinberga, I., Daugavietis, M. and Ruņģis, D. 2008. Cross-species Amplification of Betula pendula Roth. Simple Sequence Repeat Markers in Alnus Species.  Baltic Forestry 14(2): 116-121

Alnus glutinosa L. and Alnus incana L. Moench are found in natural stands throughout Latvia. Alnus species are not commercially grown in Latvia; however there is interest in utilising these species for commercial plantations due to their rapid growth rate and ability to grow in, and to improve poor quality soils. Also of interest are hybrids of these two species, as naturally occurring hybrids have been reported to be faster-growing and larger than the parent species. Molecular markers have not been widely applied or developed in Alnus species, particularly for population studies. Our aim was to identify previously developed SSR markers that could be used in Alnus, in order to investigate population structure, genetic diversity, and also to discover species-specific markers, to assist in identifying naturally occurring Alnus hybrids. We took 15 previously developed birch SSR markers, and tested these on A. glutinosa and A. incana accessions, as well as potential hybrids identified in natural forests stands. The cross-species PCR amplification success rate is high (8 from 15), however, our results show that null alleles are very likely to be a problem when using these markers in Alnus species. One of these SSR markers (L3.1) identified clear species-specific allelic separation. When this marker was applied to the morphologically identified species individuals and putative hybrids, the SSR marker results confirmed the species designations, but were not entirely correlated for the putative hybrids. It is possible that the individuals where the morphological designation did not correspond to the DNA marker species designation are not pure hybrids, but backcrosses of hybrids to one of the species. Additional species-specific markers will be required to further investigate the genetic composition of these phenotypically diverse, morphologically identified hybrids.

Key words: Alnus, SSRs, cross-species amplification, Betula