Pd. Khasa et al., Isolation, characterizaton, and inheritance of microsatellite loci in alpine larch and western larch, GENOME, 43(3), 2000, pp. 439-448
Microsatellite loci or simple sequence repeat loci (SSRs) were isolated in
alpine larch (Larix lyallii Parl.) and western larch (Larix occidentalis Nu
tt.). In total, 14 SSR loci were characterized; two [(TCT)(4, A7)] came fro
m published Larix DNA sequence data, one (CA)(17) was obtained from a parti
al non-enriched alpine larch total genomic DNA library, and the remaining 1
1 loci were obtained from larch genomic DNAs enriched for (CA)(n) repeats.
The SSR regions in these clones could be divided into three categories: per
fect repeat sequences without interruption, imperfect repeat sequences with
interruption(s), and compound repeat sequences with adjacent tandem simple
dinucleotides. Eight of the 14 loci analyzed were found to be polymorphic
and useful markers after silver-staining polyacrylamide gel electrophoresis
. In addition, several SSR primers developed for alpine larch were able to
successfully amplify polymorphic loci in its related species, western larch
, and among other closely related taxa within the Larix genus. The inherita
nce of microsatellite loci was verified by analysis of haploid megagametoph
yte and diploid embryo tissues of progeny obtained from controlled crosses
between western larch and alpine larch. All microsatellite loci analyzed ha
d alleles that segregated according to expected Mendelian frequencies. Two
species-specific markers (UAKLly10a and UAKLla1) allow easy and rapid ident
ification of specific genetic entry of alpine larch and western larch at an
y stage in the sporophyte phase of the life cycle. Therefore, these markers
are efficient in identifying the parental species and to validate controll
ed crosses between these two closely related species. These results are imp
ortant in tree improvement programs of alpine larch and western larch aimed
at producing genetically improved hybrid stock for reforestation in Wester
n Canada and U.S.A.