An AFLP estimation of the outcrossing rate of <i>Spondias tuberosa</i> (Anacardiaceae), an endemic species to the Brazilian semiarid region

Abstract

Una estimación AFLP de la tasa de fecundación cruzada de Spondias tuberosa (Anacardiaceae), una especie endémica de la región semiárida de Brasil. The umbu tree (Spondias tuberosa) is one of the most important endemic species to the Brazilian tropical semiarid region. The umbu tree has edible fruits with a peculiar flavor that are consumed in natura or in a semi-industrialized form, such as jams, candies and juices. The majority of endemic species to Brazilian semiarid region have not been studied or sampled to form germplasm collections, which increases the risk of losing genetic variability of the adapted species to xerophytic conditions. The aim of this study was to estimate outcrossing rates in S. tuberosa using a multilocus mixed model in order to guide genetic resources and breeding programs of this species. DNA samples were extracted from 92 progenies of umbu trees, which were distributed among 12 families. These trees were planted by seed in 1991 in Petrolina, PE, Brazil. The experimental design was a randomized block, with a total of 42 progenies sampled in three regions. The experimental units were composed by five plants and five replications. The outcrossing rate was estimated by the multilocus model, which is available in the MLTR software, and was based on 17 polymorphic AFLP bands obtained from AAA_CTG and AAA_CTC primer combinations. The observed heterozygotes ranged from 0.147 to 0.499, with a maximum frequency estimated for the AAA_CTC_10 amplicon. The multilocus outcrossing estimation ( ) was 0.804±0.072, while the single-locus ( ) was 0.841±0.079, which suggests that S. tuberosa is predominantly an outcrossing species. The difference between and was -0.037±0.029, which indicates that biparental inbreeding was nearly absent. The mean inbreeding coefficient or fixation index ( ) among maternal plants was -0.103±0.045, and the expected was 0.108, which indicates that there was no excess of heterozygotes in the maternal population. The outcrossing estimates obtained in the present study indicate that S. tuberosa is an open-pollinated species. Biometrical models applied to this species should therefore take into account the deviation from random outcrossing to estimate genetic parameters and the constitution of broad germplasm samples to preserve the genetic variability of the species. Outcrossing rates based on AFLP and the mixed-mating model should be applied to other studies of plant species in the Brazilian semiarid region. Rev. Biol. Trop. 61 (2): 577-582. Epub 2013 June 01.Key words: outcrossing rate, MLTR, heterozygosis.The umbu tree (Spondias tuberosa Arruda -Anacardiaceae) is a xerophytic tree species that is endemic to the tropical Brazilian semiarid region (Prado & Gibbs 1993). The high drought tolerance of this species is due to its specialized root structure (xylopodium), which plays a key role in long-term water storage. The tree has edible fruits with a peculiar flavor that are consumed in natura or semi-industrialized in different forms, such as jams, candies and juices.T...

Research Article Paternity identification in <i>Spondias</i> <i>tuberosa</i> (Anacardiaceae: Sapindales) polycrosses using microsatellite loci

“…Samples of young and healthy leaves from 20 and 44 progenies of the female plants BGU30 and BGU 37, respectively, and six putative pollinator accessions were collected and stored at -80ºC for DNA extraction. The DNA extraction was performed based on the CTAB 2x protocol, with some modifications, as described by Santos and Gama (2013). DNA quantification was obtained through comparative visual analysis of samples on 0.8% (w/v) agarose gel, stained with ethidium bromide and standardized at 10 ng µL -1 for SSR analysis.…”

“…The fruits weigh 4.5 to 96 g, are elliptical or rounded, and are rich in bioactive compounds, such as vitamin C, flavonoids, carotenoids, and phenolic compounds (Santos et al 1999, Dantas-Junior, 2008. The umbu tree is a diploid species (2n = 32), predominantly allogamous, with an estimated outcrossing rate of 80% (Almeida et al, 2007;Santos and Gama, 2013). Santos et al (1999) reported umbu fruit with an average weight greater than 85 g, a value 4x greater than the average fruit weight of the species, 21 g. Assessments of cloned umbu tree accessions resulted in the registration of four clones, BGU-52 BGU-55, BGU-48 and BGU-68, enabling the commercial production of seedlings of the species (Ministério da Agricultura, Pecuária e Abastecimento, 2021).…”

Research Article Development and transferability of microsatellite loci for <i>Spondias</i> <i>tuberosa</i> (Anacardiaceae: Sapindales), a species endemic to the Brazilian semi-arid region

“…DNA extraction was performed based on the CTAB 2x protocol, with some modifications, as described by Santos and Gama (2013). DNA quantification was made through comparative visual analysis of samples on 0.8% (w/v) agarose gel, stained with ethidium bromide and standardized at 10 ng µL -1 for SSR analysis.…”

“…The program started with 15 min at 94ºC, followed by 35 cycles at 94ºC for 30 s, 58 or 60ºC for 1 min, 72ºC for 1 min and a final extension at 72ºC for 10 min. The PCR products were visualized in a 6% polyacrylamide gel, stained with silver nitrate, as described by Santos and Gama (2013).…”

Outcrossing Rate and Genetic Variability in Mexican Race Avocado

“…and Zucc. (Lian et al, 2001), Sorghum bicolor (L.) Moench (Adugna, 2012), Spondias tuberosa Arruda (Fernandes and Cândido de Souza, 2013), Theobroma cacao L. (Efombagn et al, 2009), T. grandiflorum (Willd. ex Spreng.)…”