XIANG, QIU-YUN1*, DANIEL J. CRAWFORD2, CLAUDE W. DEPAMPHILIS3, AND ANDREA D. WOLFE2. 1Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007; 2Department of Plant Biology, Ohio State University, Columbus, OH 43210; 3Department of Biology, Vanderbilt University, Nashville, TN 37235. - Assessing genetic diversity in complex hybrid zones of Aesculus L. (Hippocastanaceae) using hypervariable DNA markers.
The genus Aesculus represents one of the best known examples of
hybridization and introgression in plants, with four species of Sect.
Pavia (A. pavia, A. sylvatica, A. flava, and A.
glabra) contributing to two complex hybrid zones. Hypervariable
Inter-Simple Sequence Repeat (ISSR) markers amplified via PCR were used to
assess genetic diversity within the four species and their hybrids
(A. sylvatica X pavia, A. glabra X flava,
A. flava X sylvatica X pavia, A. sylvatica
X flava). Results indicated that the ISSR markers are highly
polymorphic in Aesculus and that a high level of genetic diversity
is maintained within the hybrid zones. Each ISSR primer generated 16 - 27
bands and 96% of
all of the bands observed are polymorphic (present in 95% - 5% of all
the individuals examined). The bands observed are also highly
polymorphic within species and populations. Estimated genetic similarities
within and between populations show relatively low averages, but the range
of values is high (0.513-0.923, Ave. 0.697
within populations, and 0.338-0.692, Ave. 0.4938 between populations).
The ISSR data were analyzed using the Neighbor-joining method to
determine the genetic structure of the hybrid zones. Results of this
analysis support the previous findings from allozyme data that these
hybrid zones have an asymmetrical structure.
Key words: Aesculus, genetic diversity, Genetic structure, Hippocastanaceae, Hybridization, ISSR