Molecular Characterization of Apricot Germplasm from an Old Stone Collection

Increasing germplasm erosion requires the recovery and conservation of traditional cultivars before they disappear. Here we present a particular case in Spain where a thorough prospection of local fruit tree species was performed in the 1950s with detailed data of the origin of each genotype but, unfortunately, the accessions are no longer conserved in ex situ germplasm collections. However, for most of those cultivars, an old stone collection is still preserved. In order to analyze the diversity present at the time when the prospection was made and to which extent variability has been eroded, we developed a protocol in apricot (Prunus armeniaca L.) to obtain DNA from maternal tissues of the stones of a sufficient quality to be amplified by PCR. The results obtained have been compared with the results from the profiles developed from apricot cultivars currently conserved in ex situ germplasm collections. The results highlight the fact that most of the old accessions are not conserved ex situ but provide a tool to prioritize the recovery of particular cultivars. The approach used in this work can also be applied to other plant species where seeds have been preserved

Polyploidy in Fruit Tree Crops of the Genus Annona (Annonaceae)

Genome duplication or polyploidy is one of the main factors of speciation in plants. It is especially frequent in hybrids and very valuable in many crops. The genus Annona belongs to the Annonaceae, a family that includes several fruit tree crops, such as cherimoya (Annona cherimola), sugar apple (Annona squamosa), their hybrid atemoya (A. cherimola × A. squamosa) or pawpaw (Asimina triloba). In this work, genome content was evaluated in several Annona species, A. triloba and atemoya. Surprisingly, while the hybrid atemoya has been reported as diploid, flow cytometry analysis of a progeny obtained from an interspecific cross between A. cherimola and A. squamosa showed an unusual ploidy variability that was also confirmed karyotype analysis. While the progeny from intraspecific crosses of A. cherimola showed polyploid genotypes that ranged from 2.5 to 33%, the hybrid atemoyas from the interspecific cross showed 35% of triploids from a total of 186 genotypes analyzed. With the aim of understanding the possible implications of the production of non-reduced gametes, pollen performance, pollen size and frequency distribution of pollen grains was quantified in the progeny of this cross and the parents. A large polymorphism in pollen grain size was found within the interspecific progeny with higher production of unreduced pollen in triploids (38%) than in diploids (29%). Moreover, using PCR amplification of selected microsatellite loci, while 13.7% of the pollen grains from the diploids showed two alleles, 41.28% of the grains from the triploids amplified two alleles and 5.63% showed up to three alleles. This suggests that the larger pollen grains could correspond to diploid and, in a lower frequency, to triploid pollen. Pollen performance was also affected with lower pollen germination in the hybrid triploids than in both diploid parents. The results confirm a higher percentage of polyploids in the interspecific cross, affecting pollen grain size and pollen performance. The occurrence of unreduced gametes in A. cherimola, A. squamosa and their interspecific progeny that may result in abnormalities of ploidy such as the triploids and tetraploids observed in this study, opens an interesting opportunity to study polyploidy in Annonaceae

Mapping Genetic Diversity of Cherimoya (Annona cherimola Mill.): Application of Spatial Analysis for Conservation and Use of Plant Genetic Resources

There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at province and department level in Ecuador and Peru, respectively

Base de datos de abejas ibéricas

Las abejas son un grupo extremadamente diverso con más de 1000 especies descritas en la península ibérica. Además, son excelentes polinizadores y aportan numerosos servicios ecosistémicos fundamentales para la mayoría de ecosistemas terrestres. Debido a los diversos cambios ambientales inducidos por el ser humano, existen evidencias del declive de algunas de sus poblaciones para ciertas especies. Sin embargo, conocemos muy poco del estado de conservación de la mayoría de especies y de muchas de ellas ignoramos cuál es su distribución en la península ibérica. En este trabajo presentamos un esfuerzo colaborativo para crear una base de datos de ocurrencias de abejas que abarca la península ibérica e islas Baleares que permitirá resolver cuestiones como la distribución de las diferentes especies, preferencia de hábitat, fenología o tendencias históricas. En su versión actual, esta base de datos contiene un total de 87 684 registros de 923 especies recolectados entre 1830 y 2022, de los cuales un 87% presentan información georreferenciada. Para cada registro se incluye información relativa a la localidad de muestreo (89%), identificador y colector de la especie (64%), fecha de captura (54%) y planta donde se recolectó (20%). Creemos que esta base de datos es el punto de partida para conocer y conservar mejor la biodiversidad de abejas en la península ibérica e Islas Baleares. Se puede acceder a estos datos a través del siguiente enlace permanente: https://doi.org/10.5281/zenodo.6354502ABSTRACT: Bees are a diverse group with more than 1000 species known from the Iberian Peninsula. They have increasingly received special attention due to their important role as pollinators and providers of ecosystem services. In addition, various rapid human-induced environmental changes are leading to the decline of some of its populations. However, we know very little about the conservation status of most species and for many species, we hardly know their true distributions across the Iberian Peninsula. Here, we present a collaborative effort to collate and curate a database of Iberian bee occurrences to answer questions about their distribution, habitat preference, phenology, or historical trends. In total we have accumulated 87 684 records from the Iberian Peninsula and the Balearic Islands of 923 different species with 87% of georeferenced records collected between 1830 and 2022. In addition, each record has associated information such as the sampling location (89%), collector and person who identified the species (64%), date of the capture (54%) and plant species where the bees were captured (20%). We believe that this database is the starting point to better understand and conserve bee biodiversity in the Iberian Peninsula. It can be accessed at: https://doi.org/10.5281/zenodo.6354502Esta base de datos se ha realizado con la ayuda de los proyectos EUCLIPO (Fundação para a Ciência e a Tecnologia, LISBOA-01-0145-FEDER-028360/EUCLIPO) y SAFEGUARD (ref. 101003476 H2020 -SFS-2019-2).info:eu-repo/semantics/publishedVersio

Foliar Pectins and Physiology of Diploid and Autotetraploid Mango Genotypes under Water Stress

The cultivation of mango in Mediterranean-type climates is challenged by the depletion of freshwater. Polyploids are alternative genotypes with potential greater water use efficiency, but field evaluations of the anatomy and physiology of conspecific adult polyploid trees under water stress remain poorly explored. We combined field anatomical evaluations with measurements of leaf water potential (Ψl) and stomatal conductance (Gs) comparing one diploid and one autotetraploid tree per treatment with and without irrigation during dry summers (when fruits develop). Autotetraploid leaves displayed lower Ψl and Gs in both treatments, but the lack of irrigation only affected Gs. Foliar cells of the adaxial epidermis and the spongy mesophyll contained linear pectin epitopes, whereas branched pectins were localized in the abaxial epidermis, the chloroplast membrane, and the sieve tube elements of the phloem. Cell and fruit organ size was larger in autotetraploid than in diploid mango trees, but the sugar content in the fruits was similar between both cytotypes. Specific cell wall hygroscopic pectins correlate with more stable Ψl of autotetraploid leaves under soil water shortage, keeping lower Gs compared with diploids. These preliminary results point to diploids as more susceptible to water deficits than tetraploids

Molecular Characterization of Genetic Diversity in Apricot Cultivars: Current Situation and Future Perspectives

In the recent years, an important renewal of apricot cultivars is taking place worldwide with the introduction of a large number of new releases, which are replacing traditional and local cultivars in many situations. To study the current genetic diversity, a group of 202 apricot accessions, including landraces and releases from breeding programs in several countries, has been characterized using 13 microsatellite markers. The diversity parameters showed higher diversity in modern releases than in landraces, but also suggested a loss of diversity associated with recent breeding. Two main clusters according to the pedigree origin of the accessions were clearly differentiated in the phylogenetic analysis based on Nei’s genetic distance. The first group comprised mostly European and North American traditional cultivars, and the second group included the majority of recent and commercial releases from breeding programs. Further population analyses showed the same clustering trend on the distribution of individuals and clusters, confirming the results obtained in the molecular phylogenetic analysis. These results provide a sight of the erosion and the decrease of the genetic diversity in the currently grown apricot and highlight the importance of preserve traditional cultivars and local germplasm to assure genetic resources for further breeding

Clustering of 58 apricot accessions from both, old stone and <i>ex situ</i> collections.

<p>(A) Dendrogram based on UPGMA analysis using the similarity matrix generated by the Nei and Li coefficient after amplification with 11 polymorphic SSR loci. The accesions from the stone collection are represented in bold; the rest are the accessions conserved <i>ex situ</i>. (B) Representative estimate of population structure. The plot represent the highest-likelihood run among ten Structure runs with <i>k</i> = 7 putative populations, represented by different colours.</p

List of the Spanish apricot cultivars from the old stone and living <i>ex situ</i> collection.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023979#pone.0023979-Herrero1" target="_blank">[23]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023979#pone.0023979-Badenes2" target="_blank">[49]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023979#pone.0023979-Got1" target="_blank">[50]</a></p

Genetic diversity parameters of the old and <i>ex situ</i> conserved genotypes analyzed in this study.

<p>Genetic diversity parameters of the old and <i>ex situ</i> conserved genotypes analyzed in this study.</p

Clustering of 34 apricot accessions from an old stone collection.

<p>(A) Dendrogram based on UPGMA analysis using the similarity matrix generated by the Nei and Li coefficient after amplification with 11 pairs of microsatellite primers. (B) Representative estimate of population structure. The plot represent the highest-likelihood run among 10 Structure runs with <i>k</i> = 5 putative populations, represented by different colours.</p