Molecular Characterization and Genetic Diversity of the Macaw Palm Ex Situ Germplasm Collection Revealed by Microsatellite Markers

Abstract

Macaw palm (Acrocomia aculeata) is native to tropical forests in South America and highly abundant in Brazil. It is cited as a highly productive oleaginous palm tree presenting high potential for biodiesel production. The aim of this work was to characterize and study the genetic diversity of A. aculeata ex situ collections from different geographical states in Brazil using microsatellite (Simple Sequence Repeats, SSR) markers. A total of 192 accessions from 10 provenances were analyzed with 10 SSR, and variations were detected in allelic diversity, polymorphism, and heterozygosity in the collections. Three major groups of accessions were formed using PCoA-principal coordinate analysis, UPGMA-unweighted pair-group method with arithmetic mean, and Tocher. The Mantel test revealed a weak correlation (r = 0.07) between genetic and geographic distances among the provenances reaffirming the result of the grouping. Reduced average heterozygosity (Ho < 50%) per locus (or provenance) confirmed the predominance of endogamy (or inbreeding) in the germplasm collections as evidenced by positive inbreeding coefficient (F > 0) per locus (or per provenance). AMOVA-Analysis of Molecular Variance revealed higher (48.2%) genetic variation within population than among populations (36.5%). SSR are useful molecular markers in characterizing A. aculeata germplasm and could facilitate the process of identifying, grouping, and selecting genotypes. Present results could be used to formulate appropriate conservation strategies in the genebank.

Species delimitation and hybrid identification of Acrocomia aculeata and A. totai by genetic population approach

“…These results are congruent with those reported in other plant species (Hu et al, 2011;Song et al, 2012;Meyer et al, 2017) and can be attributed to the location of EST-SSRs in transcribed regions of the genome and therefore be less subject to variation (Ellis and Burke 2007;Varshney et al 2005). Considering gSSR and EST-SSR together, the average number of alleles detected in this study, the polymorphism index and diversity estimates (H E and H O ) (Table 2) were higher than those found by Lanes et al (2016) and Mengistu et al (2016) and lower than those reported by Lanes et al (2015) and Araujo et al (2017) in studies using only gSSR developed forA. aculeata .…”

“…In the present study, microsatellite markers of expressed regions (EST-SSR) and genomic regions (gSSR) were adopted to elucidate the taxonomic relationship between the most economically important Acrocomia species (A. aculeata and A. totai ) and to identify possible interspecific hybrids. In the genus Acrocomia, several genetic studies performed with microsatellite markers were conducted with at most 8 gSSR loci developed for A. aculeata by Nucci et al (2008), as in Lanes et al (2015), Lanes et al (2016), Mengistu et al (2016), Neiva et al (2016), Araújo et al (2017), Coelho et al, (2018) and Lima et al (2020). Thus, this work represents the first study using both EST-SSR and gSSR markers in Acrocomia.…”

“…For the management of genetic resources through exploration or conservation, it is desirable to understand the magnitude and structure of the genetic diversity of the species. Most studies on genetic diversity in Acrocomia have been conducted with A. aculeata (Abreu et al, 2012;Oliveira et al 2012;Lanes, et al, 2015;Mengistu 2016;Silva 2013;Araujo et al, 2017).…”

Development of novel EST-SSR markers in the macaúba palm (Acrocomia aculeata) using transcriptome sequencing and cross-species transferability in Arecaceae species

“…To date, in the macaúba palm, a small number of molecular markers have been available and validated [ 32 ], and they have been used in recent studies [ 13 , 33 – 36 ]. Recently, 221 SSRs were identified in the chloroplast in a high frequency of occurrence (total mean of 1/1.75 Kb) located in intergenic spacers, coding regions, introns and tRNA genes; however, they have not been validated for the macaúba palm [ 37 ].…”

Genetic Diversity and Structure of Macaw Palm: Implications for Genetic Variability Sampling

“…The species is diploid (2n = 30) and flowers in August to November, emitting yellow flowers in inflorescences with pronounced protogyny (Scariot et al, 1991;Montoya et al, 2015). Despite favoring cross-fertilization, the macaw palm is considered to have a mixed mating system (Nucci et al, 2008;Mengistu et al, 2016). The species has areas of open vegetation with high solar incidence as its most common habitat, and it is recognized as a soil fertility indicator.…”