A genotyping by sequencing (GBS) approach was used to analyze the organization of genetic diversity in V. pubescens and V. chilensis. GBS identified 4675 and 4451 SNPs/INDELs in two papaya species. The cultivated orchards of V. pubescens exhibited scarce genetic diversity and low but significant genetic differentiation. The neutrality test yielded a negative and significant result, suggesting that V. pubescens suffered a selective sweep or a rapid expansion after a bottleneck during domestication. In contrast, V. chilensis exhibited a high level of genetic diversity. The genetic differentiation among the populations was slight, but it was possible to distinguish the two genetic groups. The neutrality test indicated no evidence that natural selection and genetic drift affect the natural population of V. chilensis. Using the Carica papaya genome as a reference, we identified critical SNPs/INDELs associated with putative genes. Most of the identified genes are related to stress responses (salt and nematode) and vegetative and reproductive development. These results will be helpful for future breeding and conservation programs of the Caricaceae family.

BackgroundPolymorphic microsatellite markers were developed for Gaultheria pumila (Ericaceae) to evaluate genetic diversity and population structure within its native range in Chile. This is a very important Ericaceae endemic to Chile with a large commercial potential. Its resistance to different abiotic conditions makes it a valuable target for genetic improvement.ResultsTen polymorphic simple sequence repeat (SSR) loci were isolated from Gaultheria pumila using new-generation 454 FLX Titanium pyrosequencing technology. The mean number of alleles per locus ranged from 2 to 4. Observed and expected heterozygosity ranged from 0.00 to 1.0 and 0.00 to 0.64, respectively.ConclusionsFrom 10 SSR markers developed for G. pumila, 9 markers are promising candidates for analyzing genetic variation within or between natural populations of G. pumila and other species from the same genus.

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Gaultheria pumila (L.f.) D.J. Middleton is a native shrub of Chile that produces edible berry fruits. This species is related to the cultivated Vaccinium species; for this reason it is currently called Chilean blueberry locally. Although G. pumila has important attributes, it has been largely ignored, and remains an unexplored genetic resource. This study investigates the genetic diversity to support the efforts to domesticate the species. Sampling was carried out in 11 sites collected from four Regions of Chile. In total, 160 individuals were collected and analyzed using a set of 10 simple sequence repeats (SSRs) markers. The average observed heterozygosity was Ho = 0.50, while the expected heterozygosity was He = 0.46. The fixation index (FIS) showed an average of -0.07, and the proportion of differentiation among populations (FST) was 0.11. The average level of polymorphic loci in all populations (PPL) was 96.97%. AMOVA showed that the genetic diversity among populations was very low (ΦPT = 6%). Significant correlations were found between genetic and geographic distance. Multivariate and Bayesian analyses identified two genetic groups. These results will be very useful to support the efforts to domesticate and increase the value of this species.

Annona deceptrix is an endemic and endangered tree from Ecuador according to the IUCN Red List of Endangered Species™. Its endangered status has been related with anthropogenic activities and some intrinsic characteristics of this species such as a low germination capacity of its seeds under natural conditions which is a serious limitation to obtain plants to establish conservation and breeding strategies. The objective of this study was to determine the seed germination capacity of A. deceptrix under different conditions and pre-germination treatments as a decisive factor in the survival of the species in ecosystems. The six pre-germination treatments were seed mechanical scarification (fine sandpaper), seed imbibitions in gibberellic acid solutions with three different concentrations (600, 700, 800 ppm) for 24 hours, imbibition of seeds in distilled water for 48 hours and direct sowing (control). For each treatment was sown twenty seeds under greenhouse conditions and germination chamber. The variables evaluated were: total number of germinated seeds, germination capacity, maximum germination value and germination energy. Mechanical scarification was the best treatment with 100 % germinated seed and showed to be significantly different than the other treatment. In this regards, the rest of the treatment the germination ranged between 35 % to 55 % and did not show statistical differences each other. In conclusion, the seeds of A. deceptrix have a low germination capacity in natural conditions and then they need a pre-germination process such as mechanical-scarification to guarantees for their performance in the ecosystems.

A micropropagation protocol for G. pumila was developed. Young shoots were collected during the growing season (October to December 2016) from a wild population in the Villarrica Volcano area in the Araucanía Region of Chile. Nodal segments were used for in vitro initiation after testing several disinfection treatments with different concentrations of sodium hypochlorite. Disinfected explants were placed onto 100% WPM basal medium (WPM100) supplemented with a range of concentrations of 2-iP (2-isopentenyladenine) to evaluate the best regeneration media during in vitro culture. Disinfection with 1% sodium hypochlorite for 40 minutes, followed by a second disinfection with 2% sodium hypochlorite for 25 minutes, and cultivation on MS basal medium supplemented with 2 mg L-1 2-iP gave the highest efficiency of disinfected plants. In the propagation stage, the highest multiplication rates were obtained when 1 mg L-1 zeatin was added to the basal WPM100 medium. In vitro rooting and preacclimation were better when elongated plants were cultivated on WPM100 supplemented with 3 mg L-1 naphthalene acetic acid. This in vitro protocol could be used to propagate genotypes of this Chilean native species and is also an important tool toward its domestication and commercial use.

Annona deceptrix (Annonaceae) is a wild endemic endangered species. This species presents relevant attributes that man can use and be considered as a consumption option, but, its natural populations have a high degree of vulnerability, due to the loss their ecosystems caused by man. This study aimed to isolate and characterize SSR loci to determine the genetic diversity in A. deceptrix and other Annonaceae. We identified simple sequence repeat (SSR) regions in a microsatellite library from A. deceptrix. 22 polymorphic Simple Sequence Repeat (SSR) loci were isolated using new-generation kit Nextera of miseq illumine technology. The mean number of alleles per locus ranged from 2 to 8. Observed and expected heterozygosity ranged from 0.00 to 1.0 and 0.00 to 0.93, respectively. These are the first microsatellite markers developed for A. deceptrix. All SSR markers developed are promising candidates for analyzing genetic diversity within or between natural populations, also of analyzing pool genic in other species of Annona genus.

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