Molecular markers were used to assess polymorphism between and within the genetic bases of coffee (i.e. Typica and Bourbon) spread from Yemen since the early 18th century that have given rise to most arabica cultivars grown world-wide. Eleven Coffea arabica accessions derived from the disseminated bases were evaluated by amplified fragment length polymorphism (AFLP) using 37 primer combinations and simple-sequence repeats (SSRs) produced by six microsatellites. Four cultivars growing in Yemen and 11 subspontaneous accessions collected in the primary centre of diversity of the species were included in the study in order to define their relationship with the accessions derived from the genetic bases of cultivars. One hundred and seven AFLP markers were used to calculate genetic distances and construct a dendrogram. The accessions derived from the disseminated bases were grouped separately, according to their genetic origin, and were distinguished from the subspontaneous accessions. The Yemen cultivars were classified with the Typica-derived accessions. Except for one AFLP marker, all AFLP and SSR markers present in the cultivated accessions were also detected in the subspontaneous accessions. Polymorphism among the subspontaneous accessions was much higher than among the cultivated accessions. It was very low within the genetic bases, confirming the historical documentation on their dissemination. The results enabled a discussion of the genetic diversity reductions that successively occurred during the dissemination of C. arabica from its primary centre of diversity.

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Mixed-charge pseudo-zwitterionic mesoporous silica nanoparticles with low-fouling and reduced cell uptake properties,

Cacao (Theobroma cacao L.) is an important economic crop in the Bolivian Amazon. Bolivian farmers both cultivate cacao, and extract fruits from wild stands in the Beni River region and in valleys of the Andes foothills. The germplasm group traditionally used is presently referred to as ''Cacao Nacional Boliviano'' (CNB). Using DNA fingerprinting technology based on microsatellite markers, we genotyped 164 Bolivian cacao accessions, including both cultivated and wild CNB accessions sampled from the Amazonian regions of La Paz and Beni, and compared their SSR profiles with 78 reference Forastero accessions from Amazonian cacao populations, including germplasm from the Ucayali region of Peru. Results of multivariate ordination and analysis of molecular variance show that CNB cacao has a unique genetic profile that is significantly different from the known cacao germplasm groups in South America. The results also show that cultivated CNB and wild CNB populations in the Beni River share a similar genetic profile, suggesting that the cultivated CNB is of indigenous origin in Bolivia. The level of genetic diversity, measured by allele richness and gene diversity in the Bolivian cacao, is moderately high, but was significantly lower than gene diversity in the other Amazonian cacao populations. Significant spatial genetic structure was detected in the wild CNB population, using analysis of autocorrelation (rc = 0.232; P \ 0.001) and Mantel tests (Rxy = 0.276; P \ 0.001). This finding is also highly valuable to support in situ conservation and sustainable use of CNB genetic diversity in Bolivia.

Coffee (Coffea spp.) is one of the world's most valuable agricultural export commodities produced by small‐scale farmers. Its germplasm, which holds useful traits for crop improvement, has traditionally been conserved in field genebanks, which presents many challenges for conservation. New techniques of in vitro and cryopreservation have been developed to improve the long‐term conservation of coffee. But a question remains as to whether these new techniques are more cost effective than field collections and more efficient at reducing genetic erosion. This study compared the costs of maintaining one of the world's largest coffee field collections with those of establishing a coffee cryo‐collection at the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE) in Costa Rica. The results indicate that cryopreservation costs less (in perpetuity per accession) than conservation in field genebanks. A comparative analysis of the costs of both methods showed that the more accessions there are in cryopreservation storage, the lower the per‐accession cost. In addition to cost, the study examined the advantages of cryopreservation over field collection and showed that for species that are difficult to conserve using seeds, and that can only be conserved as live plants, cryopreservation may be the method of choice for long‐term conservation of genetic diversity.