Rajanikanth, G , Hughes, Colin E. , Filer, Denis L. , Bailey, C. Donovan .
Origin of the widely cultivated polyploid Leucaena leucocephala inferred from phylogenetic and population genetic studies.
Leucaena (Fabaceae) comprises 17 diploid species and five wild or semi-domesticated polyploids. The polyploid L. leucocephala is widely cultivated in south-central Mexico as a minor food source and the species is pantropically naturalized following extensive cultivation as a forage crop. Initial studies suggested that L. leucocephala may have originated via hybridization between diploid taxa that were brought together in artificial sympatry in cultivation in south-central Mexico. To better understand the origin(s) of L. leucocephala, we applied a combination of maternally and biparentally inherited plastid and nuclear DNA sequences and population genetic data. In the plastid gene trees L. leucocephala consistently groups with the diploid L. pulverulenta, supporting previous hypotheses that this taxon is the likely maternal parent. Six of the seven nuclear-encoded gene trees also suggested L. pulverulenta as one of the parents. Presumably paternally derived divergent L. leucocephala sequences recovered through extensive cloning grouped with a subclade of L. lanceolata accessions in six of the nuclear gene trees. However, L. lanceolata was non-monophyletic in the most gene trees. Furthermore, the combined diploid phylogeny and AFLP-based population genetic analyses support the recognition of two divergent but morphologically cryptic and disjunctly distributed lineages within L. lanceolata. Paternally derived sequences from L. leucocephala group with L. lanceolata sequences from Oaxaca and Veracruz, where populations of L. lanceolata and L. pulverulenta occur together.
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1 - New Mexico State University, Department of Biology, Po Box 30001, Department 3Af, Las Cruces, New Mexico, 88003-8001, USA
2 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, ZH, 8008, Switzerland
3 - Oxford University, Plant Sciences, Oxford, OX1 3RB, UK
Presentation Type: Oral Paper:Papers for Sections
Location: Ballroom D/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:15 PM