Gliricidia sepium provides a variety of products important for rural
communities in tropical countries. Native populations in Meso-America
currently form an important source of seed for distribution to farmers,
but concerns centre on mechanisms which may lead to their genetic
erosion, including anthropogenic dispersal and subsequent introgression
from the related species, G. maculata.
Populations of Gliricidia were examined genetically using approaches
based on the polymerase chain reaction to test for interspecific
hybridization and introgression between G. sepium and G. maculata.
Analysis involved 13 RAPD and two RFLP-PCR markers which were identified
to have species-diagnostic distributions. Data from both approaches
corresponded and indicated three locations where multilocus genotypes
were consistent with an hybrid origin. Data at one of these sites was
consistent with introgression following hybridization. The hybrid origin
of populations was supported by the intermediate geographical location
of these sites to ‘pure’ populations of each species. Analysis of
maternally inherited organellar DNA, which involved the detection of
SSCPs in mitochondrial DNA amplification products, allowed further
delineation of genetic structure among Gliricidia populations.
Mitochondrial data indicated a high degree of organelle differentiation
between sampled locations and identified G. sepium- and G.
maculata-diagnostic haplotypes. This data supported the interpretation
of genetic structure based on RAPDs and RFLP-PCR. In addition,
cytonuclear analysis allowed the directionality of gene transfer during
the formation of hybrid populations to be described. Despite evidence
for the occurrence of interspecific hybridization and introgression
in<i> Gliricidia</i>, important resource populations of G. sepium on
the Pacific coast appear to have retained their genetic integrity.
Implications in terms of the conservation and utilization of genetic
resources within the genus are discussed.
Dawson, I.K.; Simons, A.J.; Waugh, R.; Powell, W. Detection and pattern of interspecific interactions between Gliricidia sepium and G. maculata in Mesoamerica revealed by PCR-based assays. Molecular Ecology (1996) 5 (1) 89-98. [DOI: 10.1111/j.1365-294X.1996.tb00294.x]
Detection and pattern of interspecific interactions between Gliricidia sepium and G. maculata in Mesoamerica revealed by PCR-based assays