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Abstract Here we sequenced and characterized the complete plastome of Bactris riparia, a species closely related to B. gasipaes and widely distributed in Western Amazonia. We performed a comparative genomic analysis with B. riparia and the other four Bactridinae species retrieved from GenBank. The plastome of B. riparia was 156,715 bp with a quadripartite structure. Gene content included 86 protein-coding genes (CDS), 38 tRNAs, and 8 rRNAs. Bactris riparia has 69 more base pairs than B. gasipaes, with identical numbers in IR, and more in LSC and SSC. The comparative analysis indicated that structure, collinearity, and IR/SSC borders of plastomes within subtribe Bactridinae are, in general, conserved. We predicted 69 SSRs in B. riparia plastome. Among them, ~80% consisted of A/T homopolymers. Among the 52 variable CDS, rbcL showed the highest non-synonymous rate, while the rps15 gene had the highest synonymous rate. Three genes (ccsA, cemA, and rpoC1) presented evidence of positive selection and 22 genes showed evidence of purifying selection. The phylogenetic tree based on plastome sequences set Bactris as more closely related to Astrocaryum than to Acrocomia. These new plastome data of B. riparia will contribute to studies about the diversity, evolutionary history, and conservation of palms.

Peach palm (Bactris gasipaes) is cultivated by many indigenous and traditional communities from Amazonia to Central America for its edible fruits, and is currently important for its heart-of-palm. The objective of this study was to investigate the mating system of peach palm, as this is important for conservation and breeding. Eight microsatellite loci were used to genotype 24 open-pollinated progenies from three populations of the Pampa Hermosa landrace maintained in a progeny trial for genetic improvement. Both the multi-locus outcrossing rates (0.95 to 0.99) and the progeny level multi-locus outcrossing rates (0.9 to 1.0) were high, indicating that peach palm is predominantly allogamous. The outcrossing rates among relatives were significantly different from zero (0.101 to 0.202), providing evidence for considerable biparental inbreeding within populations, probably due to farmers planting seeds of a small number of open-pollinated progenies in the same plot. The correlations of paternity estimates were low (0.051 to 0.112), suggesting a large number of pollen sources (9 to 20) participating in pollination of individual fruit bunches. Effective population size estimates suggest that current germplasm collections are insufficient for long-term ex situ conservation. As with most underutilized crops, on farm conservation is the most important component of an integrated conservation strategy.

Although originally domesticated for its fruit, exploitation of the peach palm (Bactris gasipaes Kunth) in the production of gourmet heart-of-palm has also become an important activity, hence the need for improved material for large-scale production, on employing the Pampa Hermosa landrace as the seed source. In this study 11 microsatellite markers were used to evaluate genetic divergence among 96 elite plants representing four populations of spineless peach palm from the above cited source. Genetic variability was high (H T = 0.82). The low levels of divergence [F ST (0.023), G ST' (0.005)] and the high number of migrants (Nm -3.8 to 52.2) indicated significant interpopulation gene flow. Some of the plants presented high levels of genetic divergence, but the plants were grouped independently of their geographic origins. When combined with morpho-agronomic evaluation, the results found could substantially contribute towards mounting an efficient tool for obtaining superior genotypes with wide genetic variability for improvement programs.