Leucaena (Leguminosae: Mimosoideae) Genomic Resources and a Novel Means of Recovering Hybrid Parentage from a Combination of Data Sources

The extensive application of next generation sequencing in agricultural research has focused on the most important global food crops. However, lesser-known crops in the tropics, including forest trees, are also of tremendous significance. Several such plant groups are broadly known as "multipurpose crops", often representing key elements in sustainable tropical agricultural systems. One such agroforestry system includes members of the mimosoid legume genus Leucaena, which comprises 24 neotropical nitrogen-fixing species that have been used as a human food source for as long maize. Some of these species have been transported throughout the tropics where their unusually high leaf protein content has prompted the title "alfalfa of the tropics" (particularly L. leucocephala). We have developed extensive genomic and transcriptomic resources for Leucaena. These include a PacBio derived genome assembly (ca. 750Mbp) for the self-incompatible diploid species L. trichandra and transcriptomes from all 24 species of Leucaena, including five allotetraploids. Here we present these developing resources and use them to refine the divergent diploid phylogeny for the group and to infer the parentage of allopolyploid species. The combination of nuclear, plastid, and mitochondrial genomic phylogenies robustly support a complex history of hybridization among diploid lineages and provide the framework for advances in Leucaena breeding.