Genetic Diversity and Population Structure of Piptadenia gonoacantha, a Brazilian Tree Used in Reforestation

The Brazilian Atlantic Rainforest biome is one of the richest rainforests in plant and animal species, considered a high priority biodiversity hotspot for conservation. However, approximately 92 percent of the vegetation was cleared by human occupation, so measures to maintain the native forest remnants and to restore degraded lands by reforestation have been adopted.  The secondary initial tree named “pau-jacaré” [Piptadenia gonoacantha (Mart.) Macbr, Fabaceae] is found along the southeast of the biome and is commonly used in reforestation lands. The symbiotic association between the Rhizobium genus bacterial cells and the tree’s roots enables the species to occupy abandoned areas. To access genetic diversity and population structure of P. gonoacantha, we used ten cpSSR loci to genotype 371 individuals collected in two forest remnant areas (Caetetus and Mata Santa Genebra) and two reforestation areas (Cosmópolis and Iracemápolis). Six pairs of cpSSR loci were polymorphic. AMOVA detected most of the variation among populations (83.35). Eighteen alleles were identified, resulting in sixteen haplotypes. Fourteen haplotypes are unique and two haplotypes are shared among populations. Considering the Shannon Index value, Catetus presented the highest genetic diversity (I=0.0943), followed by Santa Genebra (I=0.0614), Iracemápolis (I=0.0388) and Cosmópolis (I=0.0298), which presented the lowest genetic diversity. The Bayesian software Structure detected four clusters, one cluster for each one of the populations. These results can be used for the management of reforestation lands, using the remnant areas as a source of seeds to improve its genetic diversity.