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.
The Adapting Agriculture to Climate Change Project set out to improve the diversity, quantity, and accessibility of germplasm collections of crop wild relatives (CWR). Between 2013 and 2018, partners in 25 countries, heirs to the globetrotting legacy of Nikolai Vavilov, undertook seed collecting expeditions targeting CWR of 28 crops of global significance for agriculture. Here, we describe the implementation of the 25 national collecting programs and present the key results. A total of 4587 unique seed samples from at least 355 CWR taxa were collected, conserved ex situ, safety duplicated in national and international genebanks, and made available through the Multilateral System (MLS) of the International Treaty on Plant Genetic Resources for Food and Agriculture (Plant Treaty). Collections of CWR were made for all 28 targeted crops. Potato and eggplant were the most collected genepools, although the greatest number of primary genepool collections were made for rice. Overall, alfalfa, Bambara groundnut, grass pea and wheat were the genepools for which targets were best achieved. Several of the newly collected samples have already been used in pre-breeding programs to adapt crops to future challenges.
There are 26 maize (Zea mays L.) races found in the Andean highlands of Ecuador. Knowing the environmental characteristics of the sites where these races occur is useful to understanding their adaptive capacities and to identify germplasm potentially adapted to abiotic stress conditions. Passport data of 1186 accessions from the Ecuadorian national collection were used. On the basis of the geographical coordinates of collecting sites, data were extracted for five climatic, two geophysical, and five edaphic variables. Additionally, a specific ecogeographical land characterization map for maize landraces was developed for the Ecuadorian Andes and, subsequently, an ecogeographical category was assigned to each collecting site. Wide ecogeographical variability was detected within and among races. Maize accessions were collected at sites with a seasonal mean temperature between 8.7 and 22.9°C, temperature annual range between 10.3 and 16.9°C, and December minimum temperature between 3.4 and 16.9°C. Seasonal precipitation ranged between 363 and 1809 mm and October precipitation between 18 and 171 mm. Ten accessions were found to be potentially adapted to extremely cold environments and 40 accessions to dry conditions. Most of the accessions were obtained from farms located at altitudes between 1900 and 2800 m with flat to moderate slopes. Only 37% of accessions were collected from sites with favorable soil properties regarding texture, depth to rock, pH, organic matter content, and fertility. Maize landraces were found in 28 of the 56 ecogeographical categories identified in the region, three of which were considered to be preferred environments and 10 to be marginal environments.
The effects of artificial aging and cryopreservation methods on the germination of seeds and embryonic axes of Phaseolus vulgaris and Arachis hypogaea , were studied. Aging and cryopreservation treatments in bean seeds not affect the germination percentage, reaching values not significantly different from control. Germination percentage was higher when isolated embryonic axes were studied. Aging treatments gave rise to larger bean seedlings than the controls and cryopreservation treatments affected the size depending on the explant used. In groundnut seeds, aging treatments and cryopreservation positively affected germination and vigor of seedlings, but embryonic axes from not rehydrated aging seeds not germinate. Undried groundnut seeds not survive cryopreservation, while the dried ones showed a germination behavior superior to the control. Embryonic axes tolerate immersion in liquid nitrogen but when droplet-vitrification was used, formed callus instead of seedlings. Electrolyte leakage was always higher in embryonic axes than in seeds, both in beans and groundnut, and not to have a significant effect, under the conditions studied, on germination and vigor of seedlings. The present study evidences the possibility of cryopreserving, by simple procedures, germplasm of beans and groundnut, and to verify the aging tolerance of the seeds and embryonic axes of these important species.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3203v1 | CC BY 4.0 Open Access |
Cassava (Manihot esculenta Crantz) is a crop of nutritional and economic importance worldwide, cultivated in more than 100 tropical and subtropical countries including Ecuador, where it is traditionally cultivated in the three continental regions: Amazonia, the Coast and in the valleys of the Sierra. The purpose of this study is to characterize 195 accessions from INIAP’s Ecuadorian cassava collection through (1) morphological characterization with qualitative and quantitative descriptors; and (2) ecogeographic characterization to know the climatic, geophysical, and edaphic conditions in which cassava grows and which environments are frequent or marginal for its cultivation. For the morphological characterization, 27 morphological descriptors were used (18 qualitative and nine quantitative), and for the ecogeographic characterization, 55 variables (41 climatic, two geophysical and 12 edaphic). Four morphological groups and three ecogeographic groups were identified. Morphological variability was evidenced mainly in descriptors related to the leaves, stems, and inflorescences. In addition, it was possible to identify accessions that appear capable of growing under extreme conditions of drought and poor soils. These accessions could be used for improvement.
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